GREYWATER REUSE FOR TOILET FLUSHING

IN HIGH-DENSITY URBAN BUILDINGS IN

SOUTH AFRICA: A PILOT STUDY

Report to the
WATER RESEARCH COMMISSION

by

A. A. ILEMOBADE, O. O. OLANREWAJU AND M. L. GRIFFIOEN*

School of Civil and Environmental Engineering, University of the Witwatersrand
*
Department of Civil Engineering Science, University of Johannesburg

WRC Report No. 1821/1/11

ISBN 978-1-4312-0213-3

JANUARY 2012
 DISCLAIMER

This report has been reviewed by the Water Research Commission (WRC) and
approved for publication. Approval does not signify that the contents necessarily
reflect the views and policies of the WRC, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.

© WATER RESEARCH COMMISSION

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 EXECUTIVE SUMMARY

Introduction
Although renewable, water is a finite resource, distributed unevenly in time and
space. This distribution is increasingly more severe in arid South African
communities where the net fresh water resources reduces annually and increased
urbanization and development has led to an overall increase in water demand. A
major consumer of high quality water is toilet flushing. Domestic toilet flushing
consumes between 20-40% of domestic water demand and between 50-70% of
commercial water demand. The replacement of high quality water with greywater to
meet toilet flushing is broadly encouraged by national government due to several
reasons including the potential to reduce the overburden on traditional drinking water
sources by reducing urban drinking water demand and the opportunity to provide
reliable non-potable water services in remote locations where municipal drinking
water supplies are limited or non-existent. Greywater is wastewater from showers,
baths, spas, hand wash basins, laundry tubs, and washing machines. Depending on
certain contexts, greywater may or may not include wastewater from dishwashers
and kitchen sinks but definitely excludes toilet wastewater.

In contrast to the reasons put forward for greywater reuse, some reasons against
reuse include long payback periods, unpleasant odours, and negative perceptions.
Despite these reasons against reuse, greywater reuse for toilet flushing (amongst
other uses) continues to grow worldwide.

Internationally, greywater reuse for toilet flushing has been implemented

(successfully or not) in several places, e.g. Palma Beach hotel, Spain; Florianopolis,
Southern Brazil; Institute Agronomique et Veterinaire, Rabat, Morocco; Berlin,
Germany; Loughborough University and the Millennium Dome, United Kingdom;
Annecy Residential Building, France; the Irvine Ranch Water District, California and
Casa del Agua, Tucson, USA; Taiwan; and Ottawa, Canada.

In South Africa, greywater reuse for toilet flushing has not been as popular as
greywater irrigation. This is despite results from extensive surveys which recorded

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domestic respondents’ preference for toilet flushing similar to irrigation. This study
therefore attempted to answer the question below:

“Given the increasing scarcity of high quality water resources in many South African
communities and the need for sustainable supplemental water resources for large
quantity but lower quality water requirements (e.g. toilet flushing), how viable are
greywater reuse systems for toilet flushing in high density urban buildings?”

In response to the question above, several objectives were framed within context of
the triple bottom line attributes of sustainability and these objectives were achieved
through undertaking several tasks, i.e.:
 a detailed literature survey, which attempted to garner varied local and
international experiences regarding greywater reuse for toilet flushing;
 an extensive review of regulations and guidelines pertaining to greywater reuse
and the development of a proposed structure for a national guideline;
 the development of a database of locally available greywater reuse systems for
toilet flushing and a framework to guide the evaluation of these systems;
 implementation of a pilot greywater reuse system for toilet flushing in a non-
residential (educational) and residential (student residence) building, and
monitoring certain parameters over time;
 surveys of perceptions across potential and actual users of the implemented pilot
systems over time and awareness exercises; and
 an economical analysis (using payback period) of the pilot systems.

Findings and recommendations

The sections below summarise the key findings and recommendations of this study:

i. Amongst the potential uses for greywater presented to respondents in this study
(i.e. toilet flushing and irrigation), toilet flushing was preferred. This was due to
the perception of possibly lesser contact with the greywater if used for flushing
than if used for irrigation. In essence, the further away the greywater was to
dermal contact or ingestion, the better for respondents. Reinforcing this
perception was the preference amongst respondents for the pilot systems to be

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 installed in non-residential (public) than residential (private) buildings. It was
therefore no surprise to see that the overall assessment of the pilot greywater
system after about 7 months of operation received a higher pass mark from
respondents at WITS (non-residential) than at UJ (residential);
ii. Prior to the implementation of the pilot greywater reuse systems at the 2 sites,
most of the respondents surveyed affirmed that the concept of greywater reuse
for toilet flushing was a good idea that could benefit the environment. After
implementation of the systems, and the problems and/or discomforts experienced
by the respondents (e.g. turbid/foamy greywater in the toilet bowls often forming
an unsightly ring and unpleasant odours during flushing at certain times) there
was increased concern about hygiene. Surprisingly, this did not negate the earlier
affirmation about the concept of greywater reuse, nor did it result in the reduced
use of the greywater toilets. The pro-action of the project team in regularly
allaying concerns during awareness sessions and speedily rectifying problems is
suspected to have played a significant role in sustaining positive perceptions
amongst respondents. In essence therefore, a critical component that will sustain
beneficiaries’ confidence in greywater reuse for toilet flushing (or similar reuse
interventions) and the effective functioning of these systems, will be the pro-
active and regular community engagement, awareness and maintenance/repair
interventions by implementing agencies;
iii. Respondents younger than 21 years were generally more comfortable about

greywater reuse than older respondents and therefore should be targeted when
considering greywater reuse for toilet flushing (or similar interventions);
iv. In South Africa, there are no national regulations specifically addressing

greywater reuse and management. There are however some sections/clauses in

broad regulations which address greywater reuse and/or management, albeit to
differing degrees of detail. In these sections/clauses, there is no fundamental
objection in principle to the use of household greywater for toilet flushing, as long
as nuisances, which compromise public health and the pollution status of the
environment, are avoided. In fact, in most of the pronouncements made by
national governments, there is encouragement to reuse greywater for flushing
toilets. What is missing is the absence of national regulations and this has
created a chasm between national governments’ unequivocal encouragement for

v
 greywater reuse for toilet flushing (and irrigation) and the actual implementation
of greywater reuse and reuse systems;
v. In addition to the lack of national regulations for greywater reuse and
management, is the lack of a definition for greywater as a separate wastewater
stream that is distinct from blackwater. The implication of this is that the
understanding (and thus, legal position) of greywater is inconsistent amongst the
various municipal councils that have by-laws addressing greywater. A national
definition, and thus shared understanding of greywater is urgently needed;
vi. A consequence of the lack of national regulations is the lack of national

guidelines specifically addressing greywater reuse in South Africa. The proposed

structure for a national guideline for greywater reuse for toilet flushing is therefore
presented in this report;
vii. It is imperative that prior to the selection of a package plant for greywater reuse, it

is evaluated alongside other plants using the proposed framework developed in

this study (or similar). This is because there exists a variety of package plants
which purport to treat greywater for toilet flushing but for which limited or no data
is available to verify the claims. Preferably, a physical evaluation of the plant and
its effluent should be carried out. If an independent institution (e.g. the South
African Bureau of Standards, SABS or the Joint Acceptance Scheme for Water
Services Installation Components, JASWIC) undertook the testing and
certification (or non-certification) of these package plants, the evaluation and
selection process will be much more effective and implemented systems will
function as expected;
viii. As a result of the diverse range of locally available technologies employed for

greywater reuse, the quality of treated greywater, and consequently beneficiaries’

perceptions, is bound to vary. The technology selected for greywater reuse in this
study (i.e. low-technology and low-cost) determined the visual quality of sieved
greywater (e.g. turbid/foamy greywater and unpleasant odours) and
consequently, influenced beneficiaries’ perceptions;
ix. The low-technology, low-cost greywater reuse systems implemented produced

several pros and cons.

vi
 The pros were: (a) the systems were easy to modify to suit site conditions; and
(b) the systems required no specialised skill to conduct weekly maintenance.

The cons which had a major impact on beneficiaries’ perceptions were: (a) the
greywater system, which did not remove scum, produced visually unpleasing
(turbid/foamy) greywater especially at UJ and this was a particular concern for
beneficiaries; (b) sieved greywater retained in the tanks for more than 48 hours
and/or depleted chlorine, resulted in septic greywater which produced unpleasant
smells during flushing; (c) an erroneous pipe connection at UJ resulted in
greywater from the 1st floor bath and shower flowing into the ground floor bath
and shower and this was a major cause for concern and discomfort for residents;
(d) preliminary microbiological tests of the greywater produced by the initial
implemented greywater system showed high microbiological counts, and thus the
system was modified to include 2 inline chlorinators which provided increased
disinfection but resulted in increased operational costs; (e) the small volume of
the tank at WITS (~200 litres) in order to reduce the retention time of the
greywater often resulted in the tank emptying out during peak (teaching) periods
when the frequency of toilet flushing was high. As a result, the back-up municipal
potable water supply was often used, thus negating the potable water savings
which were to be achieved by implementing the greywater system;
x. In order to avoid the difficulties and consequently, additional costs associated
with retrofitting greywater reuse systems for toilet flushing into existing buildings,
it is preferable that reuse be incorporated into the designs for new buildings. To
achieve this, there will be need to create awareness amongst various stake-
holders.
xi. At WITS, there was on average, a total potable water savings of about 6% during

off-peak teaching periods and 10% during peak teaching periods due to
greywater reuse for toilet flushing in 2 of the 12 toilets. At UJ, there was on
average, a 25% saving in total potable water used for toilet flushing during the
academic term. From these results, WITS (non-residential), due to larger total
potable water volumes, achieved larger potable water savings (and consequently
costs) than UJ (residential);

vii
xii. Payback at WITS was achieved 17 years after implementation while at UJ,

payback was not achieved within the 20 year design life for the infrastructure.
Therefore, on the basis of users paying the full costs of the reuse systems and a
preferred payback period of 8 years, the systems at WITS and UJ were
economically unviable;
xiii. In many of the communities where payback has been within the preferred

durations (8-14 years), governments have been known to provide subsidies. In

order therefore to achieve a payback period of 8 years for the reuse systems,
initial costs at WITS will have to reduce to about 30% of its 2009 value while at
UJ, an 8 year payback could only be realised when users paid only 76.5% of the
recurrent costs.

Recommendations in brief
In brief, twelve key recommendations from this study in relation to greywater reuse
for toilet flushing were:
i. Develop (or adopt) and enforce regulations and/or guidelines for greywater reuse;
ii. Incorporate greywater reuse for toilet flushing into the design of new buildings;
iii. Do not take the technology for granted. Select a greywater treatment technology

only after a broad scrutiny and clear understanding (on the part of both the
implementing agency and beneficiaries) of available technologies, how they
function, operation and maintenance requirements, and the expected greywater
output quality. There is no “one size fits all” greywater reuse technology.
iv. If possible, only select greywater treatment technologies that have received local

certification by, e.g. SABS or JASWIC;

v. Insist on a purchase and prolonged (e.g. 12 month) service agreement with the
supplier/manufacturer of the greywater system;
vi. Budget for regular operation and maintenance, modification, and replacement

costs when installing especially low-technology and low-cost greywater treatment

systems;
vii. Aim to achieve payback within 8 years. Payback periods of more than 8 years will

be unattractive to potential beneficiaries and decision makers;

viii. Ensure greywater is collected from the correct sources within the building and

that sufficient quantities of greywater for the intended use(s) can be collected;

viii
ix. Aim for greywater quality that is visually similar to municipal potable water. If not

possible, ensure there is regular monitoring and assurance of treated greywater

quality and the monitoring of users’ perceptions towards the quality;
x. Ensure there is regular engagement and awareness with beneficiaries before and
after implementation;
xi. Target young people; and

xii. Target non-residential buildings.

Conclusion
The broad concepts of greywater reuse for toilet flushing, and potential beneficiaries’
attitudes towards adopting greywater reuse for toilet flushing as one way of
preserving/improving the environment, are laudable. However, the experiences
garnered from this study show that implementing greywater reuse for toilet flushing
in South African high density urban buildings already supplied with municipal potable
water, must be approached carefully. Implementation of greywater reuse systems for
toilet flushing should only proceed after a rigorous evaluation and conclusion on
several critical issues including: the availability of regulations or guidelines to which
the reuse system would be accountable; consideration (on the part of both the
implementing agency and beneficiaries) of the trade-offs between implementing low-
technology, low-cost, high maintenance but minimum skill required, and low
greywater quality reuse systems versus other greywater reuse system permutations;
employing accredited greywater reuse systems; targeting the most appropriate end
users, i.e. young people and non-residential buildings; achieving economic viability
based on a maximum payback period of 8 years; and the need for regular
beneficiary awareness and engagement. A cursory evaluation of the above issues
would likely result in the failure of such systems.

ix
 ACKNOWLEDGEMENTS

Our sincere gratitude goes to the following:

i. The Water Research Commission for funding this project;
ii. The project Reference Group (for providing advice and direction) consisting of the
following persons:
 Mr JN Bhagwan Water Research Commission (Chairman)
 Prof N Armitage University of Cape Town
 Mr E Hugo Johannesburg Water
 Prof H Jacobs Stellenbosch University
 Prof A Lagardien Cape Peninsula University of Technology
 Ms N Naidoo Nemai Consulting
 Mr C Tsatsi DWAF – Water Use Efficiency Directorate
 Prof JE van Zyl University of Cape Town
iii. Members of the project team who participated in various aspects of the project:

 Ms K Rahube BSc (Eng), University of Cape Town

 Mr P van Rensburg BIng (Civil Eng), University of Johannesburg
 Mr W du Plessis BIng (Civil Eng), University of Johannesburg
 Mr S Natha BIng (Civil Eng), University of Johannesburg
 Mr M van Rooyen BIng (Civil Eng), University of Johannesburg
 Ms D Botes BIng (Civil Eng), University of Johannesburg
 Mr P Crous PhD University of Johannesburg
 Ms I Deka BSc (Eng), University of the Witwatersrand
 Ms T Pitso BSc (Eng), University of the Witwatersrand
 Ms D Maboea BSc (Eng), University of the Witwatersrand
 Mr P Cebani BSc (Eng), University of the Witwatersrand
 Mrs P Chooka MSc University of the Witwatersrand
iv. The 2009, 2010 and 2011 residents of Unit 51A, Student Town, Kingsway

campus, University of Johannesburg who willingly participated in the project;

v. The Head of School, Prof M Gohnert, staff and students of the School of Civil and
Environmental Engineering, University of the Witwatersrand who willingly
participated in the project;

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 TABLE OF CONTENTS

EXECUTIVE SUMMARY............................................................................................ iii

ACKNOWLEDGEMENTS .......................................................................................... x

TABLE OF CONTENTS .............................................................................................xi

LIST OF TABLES ..................................................................................................... xvi

GLOSSARY ........................................................................................................... xviii

1. INTRODUCTION .................................................................................................... 1
1.1. Background to the study and motivation .......................................................... 1
1.2. Project objectives ............................................................................................. 5
1.3. Methodologies employed to achieve project objectives.................................... 6
1.4. Layout of this report.......................................................................................... 9

2. LITERATURE REVIEW ........................................................................................ 10

2.1. Domestic water consumption ......................................................................... 10
2.2. What is Greywater? ........................................................................................ 11
2.3. Greywater generation ..................................................................................... 12
2.4. Characteristics of Greywater .......................................................................... 13

3. CASES STUDIES OF IMPLEMENTED GREYWATER SYSTEMS .................... 23

3.1. Successful case studies ................................................................................. 23
3.2. Controversial/failed case studies .................................................................... 39
3.3. Pertinent issues from the case studies ........................................................... 51

4. INTERNATIONAL AND LOCAL REVIEW OF REGULATIONS AND GUIDELINES

REGARDING GREYWATER REUSE ...................................................................... 53
4.1. Introduction .................................................................................................... 53
4.2. Review of regulations and/or guidelines regarding greywater reuse in other
countries ................................................................................................................ 54
4.3. Review of regulations and by-laws regarding greywater reuse in South Africa
.............................................................................................................................. 63
4.4. Review of guidelines regarding greywater reuse in South Africa.................... 68
4.5. Government pronouncements regarding greywater reuse in South Africa ..... 77

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 4.6. Pertinent issues from the review of regulations, by-laws and guidelines for
greywater reuse in South Africa ............................................................................ 78

5. GREYWATER TREATMENT TECHNOLOGIES AND FRAMEWORK FOR

EVALUATING LOCALLY AVAILABLE GREYWATER TREATMENT UNITS........... 81
5.1. Review of greywater treatment technologies .................................................. 82
5.2. Database of locally available greywater units for toilet flushing ...................... 93
5.3. Development of the framework for the evaluation of greywater units ............. 94
5.4. Results and discussion on the application of the framework .......................... 97

6. IMPLEMENTATION OF THE PILOT GREYWATER REUSE SYSTEMS FOR

TOILET FLUSHING................................................................................................ 102
6.1. Location of the pilot systems ........................................................................ 102
6.2. Implementation of the pilot systems ............................................................. 105

7. PERCEPTIONS, AWARENESS AND EDUCATION REGARDING GREYWATER

REUSE FOR TOILET FLUSHING WITHIN UCT, WITS AND UJ ........................... 112
7.1. Perception survey methodology ................................................................... 113
7.2. Perception survey results ............................................................................. 116
7.3. Awareness and education ............................................................................ 129
7.4. Highlights of the perception surveys, awareness and education .................. 135

8. TECHNICAL AND ECONOMIC ANALYSES REGARDING THE PILOT

GREYWATER REUSE SYSTEMS FOR TOILET FLUSHING ................................ 137
8.1. Logging of water consumption ..................................................................... 137
8.2. Maintenance of the greywater systems at WITS and UJ .............................. 142
8.3. Pros and cons of the pilot greywater reuse systems .................................... 143
8.4. Economic analysis of the pilot greywater reuse systems ............................. 144

9. SUMMARY OF FINDINGS, RECOMMENDATIONS AND CONCLUSION ........ 157

9.1. Summary of findings and recommendations related to the social (including
regulatory) attribute ............................................................................................. 158
9.2. Summary of findings and recommendations relating to the economic (including
technical) attribute ............................................................................................... 161
9.3. Proposed structure of a national guideline for greywater reuse systems for
toilet flushing ....................................................................................................... 164
9.4. Recommendations in brief ............................................................................ 170

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 9.5. Conclusion ................................................................................................... 170
9.6. Future work .................................................................................................. 171

10. REFERENCES ................................................................................................. 172

APPENDIX A. DATABASE OF LOCALLY AVAILABLE GREYWATER TREATMENT

UNITS FOR TOILET FLUSHING ........................................................................... 184

APPENDIX B. PERCEPTION SURVEY QUESTIONNAIRES ................................ 187

APPENDIX C: PUBLICATIONS AND OTHER OUTPUT FROM THIS STUDY ...... 194

xiii
 LIST OF FIGURES

Figure 1. The triple bottom line attributes of sustainability............................................... 6

Figure 2. Dual piping supplies (grey and potable water) into a toilet cistern.................. 26
Figure 3. Nolde’s (1999) recommended optimal greywater treatment train ................... 27
Figure 4. Dark greywater reuse at the household level in Nicosia, Cyprus ................... 29
Figure 5. A simple untreated greywater reuse system in Tokyo .................................... 35
Figure 6. (Above) A schematic of the Ewasha greywater reuse technology. (Below)
One of the vehicle wash services in Durban ................................................ 37
Figure 7. (Left) One of the centre’s toilets reusing greywater for flushing. (Right)
Several submerged filters and tanks that house the pumps that convey
greywater to the toilet bowls ......................................................................... 38
Figure 8. The Pontos greywater treatment system ........................................................ 39
Figure 9. Quayside Village greywater reuse System ..................................................... 45
Figure 10. Greywater treatment for non-drinking urban reuses (Li et al., 2009). ........... 83
Figure 11. An immersed membrane bioreactor (Jefferson et al., 2001) ........................ 86
Figure 12. A rotating biological contactor (Jefferson et al., 2001) ................................. 87
Figure 13. Cross-section of a reed bed (Bart Senekal Inc, 2003) .................................. 93
Figure 14. View of the (Left) south side and (Right) east side (main entrance) of the
School of Civil and Environmental Engineering, WITS............................... 103
Figure 15. The rear of Unit 51A, Student Town, University of Johannesburg.............. 105
Figure 16. Schematic of the initial greywater system for toilet flushing at WITS ......... 106
Figure 17. (Top left) The initial Unit B greywater reuse system. (Top right) The 2 mm
sieves that filter the greywater. (Bottom left) Samples of the 200 g Sanni
Tabs. (Bottom right) The female toilet connected to the greywater system 107
Figure 18. Cistern blocks used to colour the greywater............................................... 107
Figure 19. Additional backup measure in the event of greywater supply failure .......... 108
Figure 20. The sieves a few days before the awareness session (Left); after the
awareness session (Centre); and after disconnecting the laboratory
basins (Right) ............................................................................................. 109
Figure 21. Inline chlorinators installed to improve disinfection of the greywater .......... 109
Figure 22. The modified and current schematic of the greywater reuse system for
toilet flushing at WITS ................................................................................ 110
Figure 23. Schematic of the current greywater system for toilet flushing at UJ ........... 111
Figure 24 (1st). A5 posters placed in front of each hand basin; (2nd) A3 posters
placed above toilet cisterns; (3rd) A4 awareness posters about wastewater
reuse; (4th) One of the bathrooms displaying the above posters. ............... 131
Figure 25. (Left) Some residents from Unit 51A and the residents association; (Right)
Some members of the project team responding to questions. ................... 133
Figure 26. Fifth awareness meeting between Unit 51A residents and the project team135

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Figure 27. (Top left) A toilet cistern housing a manual counter with a lever; (Top
right) An electronic data logger; (Bottom left) A probe from an electronic
logger which measures voltage difference within water in the toilet cistern;
(Bottom right) Downloading data from an electronic logger unto a
computer. ................................................................................................... 138
Figure 28. Flushing trends for a typical Monday-Thursday (Top) and Saturday
(Bottom) at UJ ............................................................................................ 142

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 LIST OF TABLES

Table 1. Domestic water consumption in l/p/d for different end uses in various
countries ...................................................................................................... 11
Table 2. Domestic greywater generation in l/p/d in selected countries. ......................... 12
Table 3. Common constituents of domestic greywater .................................................. 13
Table 4. Characteristics of domestic greywater in some developed countries .............. 14
Table 5. Characteristics of domestic greywater in some developing countries ............. 15
Table 6. Analysis of dark-(dish) and light-(bath) greywater, and source water in
Stellenbosch, South Africa ........................................................................... 16
Table 7. Greywater quality and treatment requirements for different states for
unrestricted urban reuse .............................................................................. 55
Table 8. An extract of treatment processes and on-site controls for toilet flushing
water quality ................................................................................................. 58
Table 9. Japanese mandatory standards for greywater reuse ..................................... 59
Table 10. Standards for wastewater reuse quality in the European Union ................... 60
Table 11. UK quality standards for domestic greywater reuse ..................................... 60
Table 12. Canadian guideline for reclaimed water to be used in toilet and urinal
flushing ......................................................................................................... 62
Table 13. Reclaimed water standards in Kuwait ........................................................... 63
Table 14. Reference to publications/pronouncements by DWAE regarding greywater
reuse in South Africa .................................................................................... 78
Table 15. Overview of treatment technologies and their pollutant removal abilities ..... 83
Table 16. Key features of membrane filtration .............................................................. 91
Table 17. Decision-makers’ ranking of key issues to be considered when assessing
the feasibility of implementing a dual water reticulation system in South
Africa ............................................................................................................ 95
Table 18. Framework for evaluating greywater treatment units for toilet flushing (the
Technical key issue)..................................................................................... 96
Table 19. Framework for evaluating greywater treatment units for toilet flushing (the
Economic key issue) .................................................................................... 97
Table 20. Framework for evaluating greywater treatment units for toilet flushing (the
Public health and safety key issue) .............................................................. 97
Table 21. Results of the evaluation of 10 grey/waste water treatment units.................. 99
Table 22. Opposition from respondents (%) to specific uses of recycled water in
different surveys ......................................................................................... 112
Table 23. Summarised profile of respondents ............................................................. 115
Table 24. Socio-demographic response categories .................................................... 117
Table 25. Using treated greywater for toilet/urinal flushing or garden watering is
disgusting ................................................................................................... 120
Table 26. I am concerned about people getting sick from using treated greywater for
toilet/urinal flushing .................................................................................... 121
Table 27. I am comfortable using treated greywater for toilet/urinal flushing............... 122
xvi
Table 28. I am comfortable using treated greywater originating from other buildings
for toilet/urinal flushing or garden watering ................................................ 123
Table 29. I will only be prepared to use treated greywater for toilet/urinal flushing or
garden watering during a water shortage ................................................... 124
Table 30. I am comfortable for a dual water distribution system to be installed where
I currently reside......................................................................................... 125
Table 31. I am comfortable for a dual water distribution system to be installed at the
School of Civil and Environmental Engineering, WITS............................... 125
Table 32. I trust the authorities will ensure that the treated greywater is safe for
toilet/urinal flushing .................................................................................... 126
Table 33. Using treated greywater for toilet/urinal flushing or garden watering will
have a positive impact on the environment ................................................ 126
Table 34. I am satisfied with the reduction in unpleasant smells emanating from the
greywater toilet while flushing. ................................................................... 127
Table 35. I am satisfied with the improvement in the colour of the greywater. ............ 128
Table 36. How often do you use the greywater toilet?................................................. 128
Table 37. Respondents’ overall assessment of the greywater reuse system .............. 136
Table 38. Potable water savings due to greywater reuse for flushing in 2 toilets at
WITS .......................................................................................................... 139
Table 39. Potable water savings due to greywater reuse for flushing in 2 toilets at
Unit 51A, Student Town, UJ ....................................................................... 140
Table 40. Capital and recurrent costs at WITS ............................................................ 147
Table 41. Savings at WITS.......................................................................................... 148
Table 42. Cumulative cash flow at WITS..................................................................... 149
Table 43. Capital and recurrent costs at UJ ................................................................ 151
Table 44. Savings at UJ .............................................................................................. 152
Table 45. Cumulative cash flow at UJ ......................................................................... 153
Table 46. Cumulative cash flow at WITS with capital costs at 30% of initial value ...... 155
Table 47. Cumulative cash flow at UJ with users only paying 76.5% of present value
of 2009 recurrent costs .............................................................................. 156
Table 48. Greywater constituents typically measured for unrestricted urban reuse
(including toilet flushing) ............................................................................. 167

xvii
 GLOSSARY

Blackwater Wastewater collected from the bathroom and kitchen and

therefore consists of faeces, foods, fats, soaps and urine.
Dual system Two separate pipelines that supply a building with two
qualities of water for drinking and non-drinking purposes.
Effluent Water that flows out of treatment plants.
E.P. / P.E. Defined as “equivalent person” typically consuming 200
litres/p/day
Greywater Wastewater from showers, baths, spas, hand wash
basins, laundry tubs, and washing machines. Depending
on certain contexts, greywater may or may not include
wastewater from dishwashers and kitchen sinks but
definitely excludes toilet wastewater.
Non-potable water Water that is not suitable for drinking.
Potable water Water that is considered safe for human consumption.
Recycling See Reuse.
Reuse An umbrella term for the process of treating non-potable
water for potable and/or non-potable use
Wastewater Water carrying contaminants. Note that wastewater to
one user may be a desirable supply or resource to the
same or another user at a different location for a different
purpose.

xviii
 1. INTRODUCTION

1.1. Background to the study and motivation

Although renewable, water is a finite resource, distributed unevenly in time and

space. This distribution is increasingly more severe in arid communities where the
net fresh water resources available reduces annually and increased urbanization and
development has led to an overall increase in water demand. This water demand
has traditionally been met with water from the best available sources. However, over
the years, it has become evident that high quality water sources in many provinces
(e.g. Western Cape, Northern Cape and Limpopo) are inadequate to meet demands
and, that not all uses require the same water quality. Some water uses can be
supplied with water of an inferior quality, which frees the high quality sources for
higher quality uses. This is nothing new in the history of mankind since by 226 A.D.,
Rome already had eleven aqueducts and each one had its own quality of water and
specific use (Duncan, 2002).

The largest percentage (62%) of South Africa's water demand occurs in the irrigation
sector (DWAF, 2004c) with the highest proportion of this demand being private
irrigation (59%). By volume, irrigation is also one of the major inefficient water users
in South Africa (Stevens and Stimie, 2005). Another major consumer of high quality
water is toilet flushing. Domestic toilet flushing consumes between 20-40% of
domestic water demand (DWAF, 2007) and between 50-70% of commercial water
demand. Any savings in the above sectors will certainly make a significant difference
in drinking water allocation for other uses and users.

The replacement of scarce drinking water with less quality water (e.g. greywater) to
meet some non-potable water demands such as flushing of toilets, fire fighting and
lawn irrigation is encouraged in several places due to one or more of the reasons
below:
i. the potential to reduce the overburden on traditional drinking water sources by
reducing urban drinking water demand by between 30-70% (Radcliffe, 2003);

1
ii. the opportunity to provide reliable non-potable water services in remote locations
where municipal drinking water supplies are limited or non-existent;
iii. mitigating the rising costs of drinking water treatment by reducing the quantity of

chemicals required to treat drinking water and in the reduction of sludge which
arises during the treatment of drinking water;
iv. the potential to reduce sewage discharges to water bodies; and

v. exploiting the nutritional benefits of using suitably treated non-potable water in

irrigation.

Greywater is broadly referred to as wastewater from showers, baths, spas, hand

wash basins, laundry tubs, and washing machines. Depending on certain contexts,
greywater may or may not include wastewater from dishwashers and kitchen sinks
but definitely excludes toilet wastewater. Blackwater, which refers to toilet
wastewater and greywater, is a distinct wastewater stream in quality to greywater. As
a result, greywater which at generation is a better quality resource than blackwater,
can be beneficially and appropriately employed for certain non-potable water
requirements (such as toilet flushing). To reduce contaminants in greywater, several
communities (e.g. Australia and USA) exclude kitchen and related wastewaters
which typically contain significant microbial loads, foods, fats, oils and grease.

Internationally, greywater reuse for toilet flushing has been successfully implemented
in several places, e.g. Palma Beach hotel, Spain (March et al., 2004); Florianopolis,
Southern Brazil (Ghisi and Ferreira, 2007); Institute Agronomique et Veterinaire,
Rabat, Morocco (El Hamouri et al., 2007); Berlin, Germany (Nolde, 1999);
Loughborough University (Surendran and Wheatley, 1998) and the Millennium Dome
(Hills et al., 2001) United Kingdom; Annecy Residential Building, France (Lazarova,
2001); the Irvine Ranch Water District, California (Lewinger and Young, 1988) and
Casa del Agua, Tucson (Karpiscak et al., 2001) USA; Taiwan (Chin-Jung et al.,
2005); and Ottawa, Canada (Oasis Design, 2006). In contrast, some of the failures,
negatives and controversies surrounding greywater reuse systems include long pay-
back periods, outbreak of water-borne diseases due to greywater ingestion, clogging
or fouling of filters, unpleasant odours, negative perceptions, and/or
sediment/microbial accumulation in the storage tank. Despite the latter, one or more

2
of the drivers for greywater reuse listed above have continued to motivate growing
greywater reuse for several purposes including toilet flushing.

Because of the potential risks to public health due to the possible ingestion of
contaminated greywater, greywater reuse in South Africa is viewed with caution and
not commonly practised. The most common greywater reuse sites in South Africa
have been experimental domestic irrigation and non-domestic irrigation and this
reuse has been driven by the heightened awareness of the nutritional benefits of
applying suitably treated greywater to the irrigation of plants and the need to
efficiently manage greywater disposal in especially non-sewered areas (Rhodda et
al., 2010 and Carden et al., 2007). Some of the innovative irrigation methods
designed for greywater reuse include the Wagon Wheel Irrigation System developed
by the Institute for Deciduous fruit, Vines and Wine (Infruitec-Nietvoorbij) at the
Agricultural Research Council (ARC), which has been installed at a number of sites
in South Africa (Albertse, 2000). The tower garden is another interesting concept
(derived from a project in Kenya), which consists of vegetables growing around the
sides of a column of soil surrounding a central stone-packed drain (Crosby, 2004).
Greywater is poured on top of the stones and filters slowly through the soil column.
These systems were primarily designed for low-cost, small-scale irrigation with
greywater, but have also been applied commercially in some high-income sewered
areas (Alcock, 2002). Khosa (2003) describes an on-farm study using the ‘Drum and
Drip’ micro-irrigation system (an adapted low-cost irrigation system for use on small
holdings) in two settlements in Limpopo province.

Greywater has also been employed for irrigating crops a formal housing community
(Wyebank near Hillcrest) and an informal housing community (Mandela Park) that
did not have any drainage systems in place. Other examples include the collection,
sieving, disinfection and reuse of greywater (bathroom and kitchen wastewater) from
about 110 sewered and non-sewered households in Carnarvon in the Northern Cape
for lawn and vegetable garden irrigation (Ilemobade et al., 2009a); and the direct
application of greywater from washing machines for irrigating lawns and kitchen
greywater via a below surface rock-filled trench to also irrigate lawns at the Hull
street housing complex in Kimberley in the Northern Cape (Ilemobade et al., 2009a).

3
Several of the above systems were discontinued (e.g. Wyebank and Mandela Park)
due to possible health implications, e.g. the consuming of crops irrigated with
contaminated greywater, children or pets playing in and ingesting contaminated
greywater used to irrigate fields/lawns, and the potential contamination of ground
water.

In South Africa, greywater reuse for toilet flushing has not been as popular as
irrigation. This is despite results from extensive surveys conducted by Ilemobade et
al. (2009a and 2009b) which record domestic respondents’ preference for non-
potable water reuse for toilet flushing similar to irrigation. Some sites that have
however employed greywater reuse for toilet flushing include (i) the Creche within
the Old Mutual building in Pinelands, City of Cape Town where greywater from hand
wash basins is collected, sieved, disinfected and used to flush 30 toilets (Water
Rhapsody Conservation Systems, 2011) and a building in the City of Cape Town
which houses 7 apartments and uses a highly technical system to biologically purify,
store and reuse greywater (from bath tubs, hand wash basins and showers) for toilet
flushing (Kieslich, 2009). If correctly implemented and managed, greywater reuse for
toilet flushing may likely mitigate several of the reasons why greywater reuse for
irrigation has been found to be unsuitable.

A dual water reticulation system comprises two sub-systems – a conventional

system that meets potable end uses and a separate system that meets non-potable
end uses within a building. In this report, the separate system comprises the
components that collect, treat, store and supply greywater for toilet flushing. Dual
grey and drinking water reticulation systems (henceforth, dual systems) are
particularly promising for application in high-density urban buildings (HDUBs) located
in arid South African environments. This is because HDUBs:
i. are typically generate significant volumes of greywater per unit area as compared
to stand alone dwellings;
ii. are typically cost less in terms of rent/mortgage than stand alone houses and
therefore attract low to middle income earners who are looking for value for
money. Hence, the installation of a dual system may likely provide cost savings
which may be an attractive incentive for residents;

4
iii. are typically multi-storey buildings with centralised service areas and hence, the

installation of the greywater reuse system will likely be easier for plumbers
looking to connect several households within a building than as comparison to
several stand alone households spread over large area; and
iv. are reasonably access-controlled and centrally managed and hence, potential

risks to public health can be mitigated.

In terms of national and municipal regulation and guidelines for implementing dual
systems and greywater reuse for toilet flushing, South Africa is deficient. The local
instances of greywater reuse cited above have depended primarily on growing local
experience and/or international regulation/guidelines. This gap therefore provides
impetus for research.

Based on the above, the question currently driving the need for a South African
investigation into the reuse of greywater for toilet flushing is:

“given the increasing scarcity of high quality water resources in many South African
communities and the need for sustainable supplemental water resources for large
quantity but lower quality water requirements (e.g. toilet flushing), how viable are
greywater reuse systems for toilet flushing in high density urban buildings?”

This project aims to provide a response to this question.

1.2. Project objectives

In addressing the above question, the objectives of this study were framed within
context of the triple bottom line attributes of sustainability, i.e. economic, social and
environment (Figure 1). The economic attribute incorporated technical criteria, the
social attribute incorporated regulatory criteria and the environment attribute (which
focused on greywater quality) was addressed only within context of the desktop
studies and not in the pilot study.

5
Figure 1. The triple bottom line attributes of sustainability

Hence, the objectives of this study were:

i. To review knowledge and experience in greywater reuse and reuse systems
specifically for toilet flushing;
ii. To interrogate regulations and guidelines pertaining to greywater reuse for toilet
flushing in South Africa and to propose a structure for a national guideline;
iii. To collate a database of locally available greywater reuse systems suitable for

toilet flushing and to develop a robust framework for evaluating these systems for
local implementation;
iv. To monitor perceptions of potential and actual beneficiaries towards the

implementation of greywater reuse systems primarily for toilet flushing;

v. To implement and monitor a pilot greywater reuse system for toilet flushing at 2
distinct water users, i.e. a residential and educational building; and
vi. To undertake an economical analysis of the pilot greywater reuse systems;

1.3. Methodologies employed to achieve project objectives

Literature surveys
Literature surveys were carried out to document the varied characteristics of
greywater; successful and failed/controversial greywater reuse systems for toilet
flushing; greywater treatment criteria, technologies and locally available systems;
regulations and guidelines regarding greywater reuse internationally and locally; and
a diversity of social, institutional, economical, technical, environmental, and public
health issues that have arisen with the use of greywater reuse systems. The

6
literature surveys laid the foundation for the succeeding methods employed in the
study.

Surveys of locally available greywater reuse systems for toilet flushing and
development of the selection framework
In the literature survey, the qualities of greywater suitable for toilet flushing and
typical greywater treatment technologies were investigated. This review was
undertaken to determine the variety of greywater reuse technologies manufactured
locally or imported. To this end, several related Water Research Commission
reports, relevant databases and literature were investigated and advertised
manufacturers, retailers and importers of greywater and wastewater treatment
technologies were contacted and questionnaires administered to determine the
specifications of their greywater/wastewater systems and typical effluent output.
Based on the data collated, a framework was developed, using robust criteria and
benchmarks, to assist in the selection of the most appropriate greywater reuse
system for the selected pilot sites. This framework may be employed to guide future
decision-making regarding the selection of appropriate reuse technology(ies) to be
implemented for different purposes.

Perception surveys
Perception surveys, using 3 sets of questionnaires, were administered to potential
and actual beneficiaries of the implemented greywater reuse systems for toilet
flushing. The questionnaires monitored critical perceptive factors known in literature
to influence non-potable water reuse amongst a diversity of respondents. The
questionnaires were administered to respondents within the universities of the
Witwatersrand, Johannesburg and Cape Town over the period 2008-2010. After the
first set of questionnaires were administered to potential respondents in the 3
institutions in 2008 and 2009, the pilot study locations were selected (i.e. an
academic building at the university of the Witwatersrand and a student residence at
the University of Johannesburg). Subsequent to the implementation of the greywater
reuse systems at the selected sites, the second and third sets of questionnaires
were administered to beneficiaries while concurrently monitoring perceptions.

7
Implementation and monitoring of 2 pilot greywater reuse systems for toilet flushing
A pilot greywater system for toilet flushing was implemented for 2 distinct end users
– an educational building (the School of Civil and Environmental Engineering) at the
University of the Witwatersrand, (WITS) and a residential building at the Student
Town residence of the University of Johannesburg, Kingsway campus (UJ). This
section of the study involved the following:
i. Monitoring, prior to installation of the greywater reuse system and afterwards,
toilet flushing and bulk potable water demands at the 2 buildings. This exercise
was undertaken to determine the quantities of greywater which would be required
to flush toilets and therefore, the potential potable water savings and sewage
volume reductions that may be achieved from greywater reuse for toilet flushing;
ii. Administering perception surveys and awareness sessions with beneficiaries in
the 2 buildings in order to monitor evolving perceptions; This exercise was
undertaken to involve beneficiaries in the project prior to and after
implementation; inform beneficiaries of their responsibilities towards the
functionality and sustainability of the system; and receive feedback (in the form of
comments, suggestions, complaints, etc.) which assisted in the modification of
subsequent questionnaires and the modification of the greywater reuse system to
suit user requirements;
iii. Retrofitting the existing buildings’ plumbing components and installing the
selected greywater reuse systems to flush 2 toilets within each building;
iv. Monitoring the electricity consumption of the pumps;
v. Weekly maintenance of the greywater reuse system (i.e. cleaning the filters,
chlorine disinfection capsules and greywater tank sides; replenishing cistern
blocks which provide colouring and chlorine tablets; and inspecting the system to
ensure there are no leaks, breaks or missing components) to ensure it optimally
functions;
vi. Training relevant personnel on how to operate and maintain the greywater reuse
system;

Economical analysis of the implemented pilot greywater reuse systems

Subsequent to implementation and monitoring, a desktop exercise was carried out to
economically analyse the implemented greywater reuse systems. Since the length of

8
payback on reuse projects stands out in the literature as a significant contributor to
potential beneficiaries’ and decision-makers’ interest in the technology and thus
overall viability, the payback period is computed for the 2 greywater reuse systems.

1.4. Layout of this report

The 1st chapter of this report presents the background and motivation and
consequently, objectives of this study. A summary of the methodologies employed to
achieve the objectives are also presented in this chapter. The 2nd and 3rd chapters
document local and international experience regarding greywater, greywater reuse
and reuse systems. Chapter 4 reviews international and local regulations and
guidelines governing greywater reuse and reuse systems while Chapter 5 presents a
broad review of existing greywater treatment technologies and then develops the
framework for selecting an appropriate greywater reuse system amongst a diversity
of locally available options. The sites which were selected and the implementation of
the pilot greywater systems are discussed in Chapter 6. The methodology and
highlights from the perception surveys, awareness and education sessions are
presented in Chapter 7. Chapter 8 presents the technical highlights and economic
analysis of the pilot systems while Chapter 9 presents the summary of findings,
recommendations and conclusions of this study.

9
 2. LITERATURE REVIEW

2.1. Domestic water consumption

Water consumption depends on several factors (e.g. the degree of aridity, income,
level of development, level of services, household occupancy and culture) and is
typically measured as litres per person per day (l/p/d). Water consumption tends to
increase with increasing income, decreasing household occupancy and increased
level of development. In the UK, a water consumption range of 102 to 212 l/p/d was
reported between 1991 and 1998 (Table 1). This compares well with the values of
115-260 l/p/d (Griggs et al., 1997) presented for the rest of Europe about the same
time but is lower in comparison to the 450 l/p/d published for Zurich, Switzerland
(Stanner and Bordeau, 1995). The water consumption figures for the USA about 2
decades before, appears to be within the range published in Table 1 for the UK. In
1998, a water consumption figure as high as 1136 l/p/d (which is likely to have
included garden irrigation) was reported for some arid areas in the US.

A breakdown of typical domestic water usage in various countries (Table 1)

demonstrates that the proportions of water used for different purposes in household
are similar. Daily toilet flush water per capita is roughly a third of total domestic water
consumption and slightly larger than the combination of bath, shower and hand wash
basin water consumption. Butler et al. (1995) estimates that the toilet consumes
about 40% of the total instantaneous flow during the day and up to 90% at night.
One implication of this figures is that domestic greywater generated from the bath,
shower and washbasin can roughly satisfy toilet flush water demand. However, since
greywater from the bath, shower and wash basin is typically generated over a short
duration of each day and toilet flushing typically occurs over a prolonged period over
each day, there is need to store greywater to meet the flushing demand.

10
Table 1. Domestic water consumption in l/p/d for different end uses in various
countries
(Laine, 2001)

Wheatley (1998)

Van der Hoek et

Mikkelsen et al.
Surendran and

Siegrist et al.
Ligman et al.
Laak (1974)
(1991,1993)

al. (1999)
Butler

(1999)

(1974)

(1976)
Reference

Country UK UK Denmark The USA USA USA

Netherlands
Toilet 31 61.2 40 30.5 75 76 36
Kitchen 13 29.7 20 10.5 14 13 18
Wash basin 13 25.5 - 5.4 8 - -
Bath and shower 28 34.4 45 59.7 32 47 38
Washing machine 17 25.6 10 23.1 28 38 41
Other - 35.9 45 15.4 - 6
Total (l/p/d) 102 212.3 160 144.6 157 180 133

2.2. What is Greywater?

Residential wastewater (i.e. blackwater) is a mixture of household wastewater from

the following sources – bathroom hand wash basins, bathtubs, showers, toilets,
kitchen sinks, washing machines, laundry tubs and dish washers. Blackwater is
characterized by high concentrations of organic contaminants, disease and non-
disease causing microorganisms and chemicals. This wastewater may be
disaggregated into two sub-categories of greywater (i.e. light greywater and dark
greywater) based on organic strength or the levels of contaminants contained in the
water:
i. Light greywater typically consists of wastewater from bathroom hand basins,
bathtubs, showers, and laundry. Light greywater generally has lower
concentrations of contaminants than blackwater and dark greywater.
ii. Dark greywater is a combination of light greywater and wastewater from kitchen
sinks, dishwashers, or other sinks involving food preparation. Food waste,
grease, oils and cleaning products contribute significantly to increased
contaminant loading and disease-causing microorganisms when combined with
light greywater.

11
2.3. Greywater generation

The volume and pattern of greywater generated in a household varies and is

influenced by factors such as total potable water consumption, water supply level of
service, number of household members, age distribution of household members,
lifestyles, and water use pattern. Greywater volume in low-income areas of South
Africa with water scarcity and rudimentary forms of water supply (e.g. community
taps or wells) can be as low as single-digit volumes per person per day in
households where surface water bodies (e.g. rivers or lakes) are used for personal
hygiene. On the other hand, households in middle- to high-income areas with piped
water reticulation may generate significant volumes per person per day. It is
estimated that on average, typical greywater generation in South African households
with piped water reticulation may likely range between 45-80 l/p/d (approximately
50% of total water consumption). Table 2 shows greywater generated from different
end uses in households which have piped water reticulation in different countries. On
average, light greywater comprises between 70%-85% (69-96 l/p/d) of total
greywater generated in most of the countries that have disaggregated figures for
different end uses.

Table 2. Domestic greywater generation in l/p/d in selected countries.

house.gov.a

Faruqui and
Al-Jayyousi
www.green

Surendran

Wheatley

Shrestha
Helvetas
Friedler
Busser

Martin

(2008)

(1999)

(2002)
(2006)

(2004)

(2005)

(2005)

and
u

UK
Switzerland

Australia

Malaysia
Vietnam

household
Country

University

Jordan
Domestic

Nepal
Israel

hall

Water In- In- In-house In- In- In- In- In-

source house house taps house house house house house
taps taps taps taps taps taps taps
Kitchen 15-20 30 28 17 - - - - -
Bath & 30-60 55 52 62 - 46 34 - -
shower
Laundry 15-30 13 30 34 - 14 26 - -
Wash - - - - - 44 24
basin
Total 80-110 98 110 113 225 10 84 72 30-50
4
Wheatley and Surendran (2008) show that a morning greywater generated peak flow
12
is typically followed by two major peak flows – one about noon and the other about
19h00 in the evening. A minimum flow of less than 1 l/p/hour occurs between 02h00
and 05h00, corresponding to occupants’ sleeping hours. Butler (1993) documents
that blackwater from different end uses, flows more frequently in households with
more occupants than in those with less occupants. At weekends, the morning
blackwater peak flows are more extended and smaller than during the week, and
typically appear after a delay of 1 to 2 hours. Butler et al. (1995) estimates that the
greywater generated from the bath and shower end uses, constitutes up to 66% of
the total instantaneous discharge in the early morning between 04h00 and 08h00
and in the evenings between 18h00 and 22h00.

2.4. Characteristics of Greywater

The characteristics of domestic greywater vary over time and space. Three factors
significantly affect greywater composition: water supply quality, the condition of the
components conveying greywater from point of discharge, and the water related
activities in the house (Eriksson et al. 2002). Table 3 indicates the likely constituents
of water from various household sources.

Table 3. Common constituents of domestic greywater

(CSBE, 2003)

13
Greywater quality will vary based on the end uses of water. For example, cooking
habits as well as the amount and type of soaps and detergents will significantly
determine the level of contamination in greywater. The heterogeneity of greywater
therefore complicates both the treatment and the assessment of the risk of reuse
(Rose et al., 1991). Tables 4 and 5 show the heterogeneous characteristics of
greywater in both developed and developing countries where greywater samples
were analysed. These figures do not reflect country averages, bur relate to specific
cases with specific settings.

Table 4. Characteristics of domestic greywater in some developed countries

Lazarova Smith Surendran Wheatley Rose Laine Christova
(2001) et al. and and et al. (2001) -Boal et al
(2001) Wheatley Surendran (1991) (1996)
(1998) (2008)
Country France UK UK UK UK
Greywater DGW LGW LGW DGW LGW LGW LGW LGW
type
BOD5 (mg/l) 275-580 33 216- 472- 81.2-110.4 - 129-155 76-200
252 536
COD (mg/l) 471-915 95 424- 725- - - 367-587 -
433 936
SS (mg/l) 71-215 36 40-76 68 37-53.7 - 58-153 48-120
NH3-N 0.6-18.8 - 0.5- 4.6- 1.6-3.8 0.15- - <0.1-15
(mg/l) 1.6 10.7 3.2
TKN (mg/l) 3.9-22.8 4 - - - 0.6-5.2 6.6-10.4 4.6-20
TP (mg/l) 5-26.7 - 1.6- 15.6- - 4-35 - 0.11-1.8
45.5 101
TC 1.8x106- 2.4x103 5x104- 7x10 - 6.1x10 6.8x103 500-
(CFU/100 1.8x108 - 6x106 5 9
- 2.4x107
ml) >2.4x1 9.4x103
06
FC(CFU/10 3.0x105- - 32- 728 - 1.8x10 - 170-
0 1.6x108 600 4
- 8.3x103
ml) 7.9x10
6
5 3
E.coli 7.6x10 - 0- - - 1.2x10 10- -
(CFU/100 2.04x107 >2.4x1 1.5x103
ml) 06
LGW = Light greywater; DGW = Dark greywater

14
Table 5. Characteristics of domestic greywater in some developing countries

Bino (2004)
Jayyousi (2002) &
Faruqui and Al-
Al-Jayyousi (2003),
Dallas et Burnat Friedler Gross Shrestha Martin
al. and (2004) et al. et al. (2005)
(2004) Mahmoud (2006) (2001)
(2005)

Country Costa Palestine Israel Israel Nepal Malay- Jordan

Rica sia
Greywater type DGW DGW DGW - - DGW DGW
BOD5 (mg/l) 167 590 477 280-688 200 129 275-2287
COD (mg/l) - 1270 822 702-984 411 212 -
TSS (mg/l) - 1396 330 85-285 98 76 316
NH4-N (mg/l) - 3.8 1.6 0.1-0.5 13.3 13 -
TN (mg/l) - - - 25-45 - 37 -
TP (mg/l) - - - 17-27 - 2.4 -
Boron (mg/l) - - - 1.4-1.7 - - -
FC(CFU/100 1.5- 3.1x104 2.5x106 5.0x105 - - 1.0x107
ml) 4.6x108
Oil&Grease - - 193 - - 190 7-230
(mg/l)
LGW = Light greywater; DGW = Dark greywater

Greywater qualities from sewered and non-sewered communities in South Africa

have been published by several authors, e.g. Alcock (2002), Kallerfelt and Nordberg
(2004) (cited in Carden et al., 2007); the Pollution Research Group of the University
of Kwazulu-Natal (Jackson et al., 2006); Stephenson et al. (2006); Engelbrecht and
Murphy, 2006; Carden et al. (2007), and Rhodda et al. (2010). Engelbrecht and
Murphy (2006) undertook an analysis of dish water, bath water and source water
from a selection of 18 respondents/households in Stellenbosch. The respondents
were selected based on their residential location within Stellenbosch, economic and
social status. A summary of the analysis of samples received from these
respondents are presented in Table 6.

15
Table 6. Analysis of dark-(dish) and light-(bath) greywater, and source water in
Stellenbosch, South Africa
(Engelbrecht and Murphy, 2006)

From the Table above, there are significant distinctions and notably large ranges
between dark greywater being more polluted than light greywater. Hence, the
justification in Australia and the USA to reuse only light greywater. As mentioned
earlier, light greywater is contaminated with oils, animal fats, chemical detergents
and food particles and hence, promotes and supports the growth of micro-
organisms. Chemical detergents used for dish washing may be very alkaline and fats
can solidify causing blockages in the pipe reticulation and natural drainage systems
of soils if used for irrigation. Whilst light greywater do not normally contain human
waste, it may contain similar micro-organisms as dark greywater. It is however safe
to say that light greywater contains much lower numbers of these organisms and is
considered safe to use if done responsibly and within a prescribed period from
collection. In terms of chemical parameters, greywater generally has higher
concentrations of chlorine, sodium and potassium with variable levels of nitrogen and
phosphorous. Greywater is also generally alkaline and has a high sodium adsorption
ratio.
16
The sections below discuss the three broad categories by which water quality is
typically analysed:

2.4.1. Physical characteristics

Physical parameters of relevance are temperature, colour, turbidity and suspended

solids. Greywater temperature is often higher than that of the water supply and
varies within a range of 18-30oC. These comparably higher temperatures are
attributed to the use of warm water for personal hygiene and cooking. These
temperatures fall within the temperature range for biological treatment processes
since aerobic and anaerobic digestion occurs within an optimal range of 25-35oC
(Crites and Tchobanoglous, 1998). The high temperatures on the other hand,
encourage bacterial growth and decreased CaCO3 solubility, causing precipitation in
storage tanks or piping reticulation systems. Suspended solids in greywater range
from 0-1553 mg/l with developed countries recording lesser amounts than that
recorded in Stellenbosch, likely due to the quality of the source waters. Also, the
highest concentrations of suspended solids are typically found in dark greywater.

2.4.2. Chemical characteristics

The chemical parameters of relevance are pH, alkalinity, electrical conductivity,

sodium adsorption ratio (SAR), biological and chemical oxygen demand (BOD5,
COD), nutrient content (nitrogen, phosphorous), and heavy metals, disinfectants,
bleach, surfactants or organic pollutants in detergents.

pH indicates whether a liquid is acidic or basic. For easier treatment for irrigation
purposes, greywater, which strongly depends on the pH of its source water, should
be in the range of 6.5-8.4 (USEPA and USAID, 2004). However, Christova-Boal et
al. (1996) observed pH values of 9.3-10 in laundry greywater, partly as a result of the
sodium hydroxide-based soaps and bleach used.

Greywater also contains salts indicated as electrical conductivity (EC). EC measures

17
salinity of all the ions dissolved in greywater including negatively charged ions (e.g.
Cl-, NO3-) and positively charged ions (e.g.Ca++, Na+). The most common salt is
sodium chloride – table salt. Other important sources of salts are sodium-based
soaps, nitrates and phosphates present in detergents and washing powders. Salinity
of greywater is normally not problematic but can become a hazard when greywater is
reused for irrigation. In laundry wastewater, sodium concentrations can be as high as
530 mg/l (Friedler, 2004) (similar to the upper limits observed in the Stellenbosch
samples), with SAR exceeding 100 for some powder detergents (Petterson and
Ashbolt, 2001). Sodium is of special concern when applied to loamy soils poor in
calcite or calcium/magnesium as a high SAR may result in the degradation of well
structured soils, thus limiting aeration and water permeability. This high sodium
problem in soils can best be avoided by using low sodium products, such as liquid
laundry detergents. While European and North American countries recommend
irrigation water with SAR < 15 for sensitive plants (FAO, 1985), Patterson (1997)
observed hydraulic conductivity problems in Australian soils irrigated with a SAR as
low as 3 in wastewater.

Biological and chemical oxygen demand (BOD, COD) are parameters used to
measure the organic pollution in water. COD describes the amount of oxygen
required to oxidise all organic matter found in greywater. BOD describes biological
oxidation through bacteria within a certain time span (normally 5 days, BOD5).
Discharging greywater with high BOD and COD concentrations into surface water
results in oxygen depletion, which is then no longer available for aquatic life. BOD
and COD concentrations in greywater strongly depend on the amount of water and
products used in the household (especially detergents, soaps, oils and fats). Where
water consumption is relatively low, BOD and COD concentrations are high. In Table
5, Dallas et al. (2004) observed an average BOD5 of 167 mg/l in dark greywater in
Costa Rica with a total water consumption of 107 l/p/d. In Palestine, where dark
greywater is also generated and the total consumption is 40 l/p/d, average BOD was
as high as 590 mg/l and exceeded 2,000 mg/l in isolated cases (Burnat and
Mahmoud, 2005).The COD/BOD ratio is also a good indicator of greywater
biodegradability. A COD/BOD ratio below 2-2.5 indicates easily degradable
greywater. While greywater is generally considered easily biodegradable with BOD

18
accounting for up to 90% of the ultimate oxygen demand (Del Porto and Steinfeld,
2000), different studies have also indicated low greywater biodegradability with
COD/BOD ratios of 2.9-3.6 (Al-Jayyousi, 2003; Jefferson et al., 2000). This is
attributed to the fact that biodegradability of greywater depends primarily on the type
of synthetic surfactants used in detergents and on the amount of oil and fat present.
While Western countries have banned and replaced non-biodegradable (and thus,
troublesome) surfactants with biodegradable detergents (Tchobanoglous, 1991),
such biodegradable resistant products may still be used (e.g. in powdered laundry
detergents) in low and middle-income countries. Greywater data collected in low and
middle-income countries indicate COD/BOD ratios within a range of 1.6-2.9. Values
close to the upper limit typically proceed from laundry and kitchen wastewater.

Greywater normally contains low levels of nutrients compared to toilet wastewater.

Nonetheless, nutrients such as nitrogen and phosphorous are important parameters
given their fertilising value for plants, their relevance for natural treatment processes
and their potential negative impact on the aquatic environment. The high
phosphorous contents often observed in greywater can lead to problems such as
algae growth in receiving waters. Dishwashing and laundry detergents are the main
sources of phosphorous in greywater. Average phosphorous concentrations are
typically found within a range of 4-14 mg/l in regions where non-phosphorous
detergents are used (Eriksson et al., 2002). However, they can be as high as 45-280
mg/l in households where phosphorous detergents are utilised, as observed for dark
greywater in the UK (Surendran and Wheatley, 1998) and Stellenbosch (Engelbrecht
and Murphy, 2006). Levels of nitrogen in greywater are relatively low with kitchen
wastewater being the main source of nitrogen in dark greywater. Nitrogen in
greywater originates from ammonia and ammonia-containing cleansing products as
well as from proteins in meats, vegetables, protein-containing shampoos, and other
household products (Del Porto and Steinfeld, 2000). In some instances, even the
water supply can be an important source of ammonium nitrogen. This was observed
in Hanoi (Vietnam) where NH4-N concentrations as high as 25 mg/l were measured,
originating from mineralisation of peat, an abundant organic material in Hanoi’s
groundwater aquifers (Duong et al., 2003).
Dark greywater is certain to contain significant amounts of fat such as vegetable oil,

19
and cooking and oil grease (O&G) originating mainly from kitchen sinks and
dishwashers. The O&G content of kitchen greywater strongly depends on the
cooking and disposal habits of households. No recommended range of values for
O&G was determined in the literature, however values as high as 230 mg/l were
observed in Jordan for mixed greywater (Al-Jayyousi, 2003) (Table 5), while Crites
and Tchobanglous (1998) recorded O&G concentrations ranging between 1,000 and
2,000 mg/l in restaurant wastewater. As soon as greywater cools down, grease and
fat congeal and can cause mats on the surface of settling tanks, on the interior of
pipes and other surfaces.

Surfactants are the main components of household cleaning products. Laundry and
automatic dishwashing detergents are the main sources of surfactants in greywater.
Other sources include personal cleansing products and household cleaners. The
amount of surfactants present in greywater is strongly dependent on the type and
amount of detergent used. Surfactants, also called surface-active agents, are
organic chemicals that alter the properties of water. They consist of a hydrophilic
head and a hydrophobic tail. By lowering the surface tension of water, they allow the
cleaning solution to wet a surface (e.g. clothes, dishes, etc.) more rapidly. They also
emulsify oily stains and keep them dispersed and suspended so that they do not
settle back on the surface. The most common surfactants used in household
cleansing chemicals are LAS (linear alkylbenzene sulfonate), AES (alcohol ether
sulphate) and AE (alcohol ethoxylate). While in most Western countries, non-
biodegradable surfactants were banned in the 1960s, these environmentally
problematic organic chemicals are still used in many developing countries, e.g.
Pakistan (Siddiq, 2005), Jordan (Bino, 2004) and South Africa. Studies conducted by
Friedler (2004) and Shafran et al. (2005) revealed surfactant concentrations in
greywater ranging between 1 and 60 mg/l, and averaging 17-40 mg/l. The highest
concentrations were observed in laundry, shower and kitchen sink greywater.

Other pollutants that could occur in greywater include heavy metals and Xenobiotic
organic compounds (XOCs). XOCs constitute a heterogeneous group of compounds
that originate from the chemical products used in households such as detergents,
soaps and perfumes. Information about the presence and levels of XOC’s is scarce

20
and it has been recommended that further research be conducted in this regard if
greywater is to be used for irrigation or groundwater infiltration, as these
contaminants may be toxic to plants and could pollute the groundwater respectively
(Eriksson et al., 2002).

2.4.3. Microbiological characteristics

Greywater may pose a public health risk given its contamination with pathogens, e.g.
viruses, bacteria, protozoa, and intestinal parasites. For light greywater, these
pathogens are primarily faecal in origin (e.g. hand washing after toilet use, washing
of babies after defecation, and diaper washing) while for dark greywater, these
pathogens originate from both faecal and food (e.g. washing of vegetables and raw
meat) contamination. Faecal contamination of greywater typically depends on the
age distribution of household members, i.e. the higher faecal contamination of
greywater is typically experienced where babies and young children are present in a
household.

The often hesitance by the pubic and decision-makers to reuse greywater stems
from the potential for human exposure which will lead to illness. Enteric viruses,
which are known to be the most critical group of pathogens, can cause illness even
at low doses and cannot be detected by routine microbial analysis. They also
represent the microbial component that is most difficult to process: it can be
assumed that a process effective in removing enteric viruses will be similarly
effective for all other pathogens (Asano, 1998). It is normal, however, to base
standards on the more readily quantifiable indicator organisms of faecal or total
coliforms since the main issue when reusing greywater is the potential risk to human
health. These indicator species demonstrate a potential for disease transmission,
rather than an actual risk of illness, but are more familiar bacteriological quality
determinands than viruses and are more easily measured. On the other hand, no
proven correlation exists between concentrations of indicator species and actual
pathogen levels, and some pathogens are known to be more resistant to treatment
than the indicator species (Asano, 1998). This has resulted in the more conservative
approach being adopted in the USA, Japan and Australia where greywater reuse is

21
an established operation. In the USA specifically, the USEPA guideline for water
recycling (USEPA, 1992) promotes non-detectable concentrations of faecal coliform
for urban reuse combined with a specification for a minimum level of treatment
required (Jefferson et al., 1999).

Greywater, which can contain at least 105/100 ml of potentially pathogenic

microorganisms, typically changes in quality over time. Research has shown that
counts of total coliform and faecal coliform increased from 100-l05/100 ml to above
105/100 ml within 48 hours in stored greywater from various sources (Al-Jayyousi,
2003). Easily bio-degradable organic compounds, which are typically found in dark
greywater, also favour the growth of microorganisms (Ottoson and Stenstrom, 2003).

22
 3. CASES STUDIES OF IMPLEMENTED GREYWATER SYSTEMS

3.1. Successful case studies

3.1.1. Palma Beach Hotel, Spain

(March et al., 2004)

Palma Beach Hotel is a three-star hotel that has 81 rooms (63 of which include a
kitchen) located on 9 floors. It is mostly occupied by foreign visitors (most of them
from Scandinavia) who come to Spain for summer holidays. Usually, customers stay
at the hotel for either 1 or 2 weeks.

A simple greywater recycling system was introduced for toilet flushing with the aim of
conserving the available potable water. The treatment involved filtration using a
nylon sock type filter (0.3 mm mesh size and 1 m2 filtration surface), sedimentation,
and disinfection with sodium hypochlorite. The treated greywater was initially stored
in a ground level tank (4.5 m3) and from there was pumped using an automatic pump
to a terrace tank, which could also be fed with drinking water, if necessary. From the
terrace tank, the toilet cisterns in the rooms were fed by gravity. The average toilet
cistern is 6 litres and average consumption on site during the study was 36
l/person/day.

While undertaking an economic analysis of the system, a 14 year payback period

was computed. The payback period was based on the seasonal characteristics of
the tourist industry with the system operating over an average of 7 months a year
with an average hotel occupancy of 85%.

In terms of educating users and determining perceptions, an informative pamphlet

was left in all the rooms. The pamphlet included a short introduction on the
importance of water management, a description of the greywater reuse project,
identification of the institutions involved, input for residents’ personal data
(nationality, age, gender, duration of stay at the hotel) and several questions
requesting residents’ perceptions regarding the reuse system (i.e. opinion on the

23
system and the quality of water in the toilet cistern). Data from residents indicated a
general satisfaction with the system. Unpleasant odours was mentioned by one of
the hotel’s customers who also gave a "fair" overall impression of his holiday period.
No complaints about the system were reported to the hotel administration. The
system has been proven to be sustainable in terms of energy consumption, land
requirements and waste production. The system also showed durability (by operating
for 1 year without any significant problems) and robustness (fluctuations in greywater
composition did not affect the maintenance program). With adequate information
given to users the social acceptance of the system was generally positive.

3.1.2. Florianopolis, Southern Brazil

(Ghisi and Ferreira, 2007)

The study was conducted to evaluate the potential for potable water savings by
using rainwater and greywater in a residential building located in Florianopolis,
southern Brazil. The building is a four-storey residential building composed of three
blocks housing 16 three bedroom flats.

In order to estimate potable water end-uses within the building, data was collected
by interviewing residents (between December 2003 and February 2004), measuring
water flow rates and obtaining water consumption figures from the local water utility.
Residents provided information on frequency of use of plumbing fixtures and
durations of water use over working days and weekends. A weighted average water
use was calculated along with frequency of use and duration of water use per
resident. From these calculations, figures were obtained per resident, flat, block and
the entire building.

An economic analysis was performed to evaluate the cost effectiveness of using

rainwater and greywater either separately or jointly. Results show that the average
potential for potable water savings (using non-potable water for toilet flushing,
clothes washing and cleaning) ranged from 39.2% to 42.7%. By using rainwater
alone, potable water savings ranged from 14.7% to 17.7%. When greywater was
used alone, potable water savings were higher, ranging from 28.7% to 34.8%. As for

24
the combined use of rainwater and greywater, actual potable water savings ranged
from 36.7% to 42.0%. One of the conclusions that were deduced from this project
was that the three non-potable water supply options investigated in the study were
cost effective as the payback periods for each were less than 8 years. In comparison
to rainwater, the greywater option proved more cost effective.

3.1.3. Institute Agronomique et Veterinaire, Rabat, Morocco

(El Hamouri et al., 2007)

This pilot study was conducted on the campus of the Institute Agronomique et
Veterinaire (IAV), Rabat, Morocco which is located next to the Club of the
Association Culturelle et Sportive de l’Agriculture (ACSA). Wastewater generated in
the showers and the toilets of the ACSA club gym is segregated thus allowing the
collection of 8 m3/d of greywater. A reservoir outside the gym collects greywater
which was then pumped through a 50-mm diameter pipe over a distance of 504 m to
the wastewater treatment facility located inside the IAV Campus.

Greywater is then treated in a two step gravel/sand filtration unit. Step 1 consists of a
planted horizontal-flow gravel filter, while step 2 is a vertical-flow multilayer sand
filter.

The horizontal-flow gravel filter is constructed of reinforced concrete and has the
following characteristics: length = 2.25 m, width = 2.0 m, and cross sectional area =
1.6 m2. After passing through the filters, greywater is disinfected in an Ultra-Violet
Tspa. The treated and UV disinfected greywater is then stored in a black,
polyethylene reservoir and conveyed, using a 50-mm diameter pipe, over a distance
of 460 metres to the building housing the Department of Rural Engineering (DRE).
The four toilets on the ground floor of this building are connected to the greywater
supply pipe. A dual piping system was adopted in the DRE building toilets to avoid
any cross connections between potable and recycled greywater. Hence, the toilet
cisterns have access to potable water when greywater is not available (Figure 2). For
comparison purposes, 4 other toilets, located on the first floor of the DRE building,
were flushed with potable water.

25
Figure 2. Dual piping supplies (grey and potable water) into a toilet cistern

The performance of the two-step unit was satisfactory. The effluents’ average
turbidity was reduced from about 28 to 2 NTU. Removal rates of COD and BOD5
were 75% and 80% respectively. Half of the nitrogen was nitrified during the filtration
process, the removal rate of phosphorus was almost 50%, while anionic surfactants
were removed at a rate of 97%. On the other hand, the gravel/sand filter
performance in Faecal Coliform removal was low and did not exceed one log unit.

3.1.4. Berlin, Germany

(Nolde, 1999)

Nolde (1999) presented two sites reusing greywater for toilet flushing in multi-storey
buildings in Germany. In the first building (a 400-bed hotel), the greywater treatment
plant, which was located in a 15 m2 basement, collected greywater from showers,
bathtubs and hand-wash basins. Biological treatment which initially consisted of a
two-stage rotating bio-contractor (RBC) was later replaced with a four-stage RBC.

The greywater treatment plant in the 2nd building consisted of a two-stage fluidized-
bed reactor which collected and treated greywater from the shower and bathtub of a
two-person household. The system had a total volume of 165 litres (the volume for
the stage 1 reactor was 105 litres and for the stage 2 reactor, 60 litres) and is placed
above the toilet in the bathroom. A cube shaped polyurethane material is used as
biofilm carrier in both stages.

26
A set of tests were undertaken to determine the quality of treated greywater from
both treatment plants. Mixed samples of the 1st plant and random samples of the 2nd
plant were taken over a period of 24 hours, immediately stored without preservation
at 4°C and processed within 24 hours. Influent samples were taken from the
sedimentation tank of the 1st plant or bathtub of the 2nd plant where greywater was
initially collected, and effluent samples were taken from the clear well or service
water tank. Testing for feacal and total coliform followed in triplicate serial dilutions
and was quantified using the Most Probable Number (MPN) method. Results from
the 1st plant showed that the effluents’ BOD7 concentration was always below the 5
mg/l control limit. In terms of the total bacterial count, the water samples produced
counts lower than the minimum microbiological standards of 100 CFU/ml and 1000
CFU/ml. These values indicated that the faecal coliform and faecal streptococci were
below the detection limit of 0.03 bacterm/l. Also, results from the 2nd plant showed
that reasonable water quality may be achieved with a smaller greywater system.

Based on the results from the two sites, Nolde (1999) suggested an optimal
greywater treatment train shown in Figure 3.

Figure 3. Nolde’s (1999) recommended optimal greywater treatment train

.

27
3.1.5. Nicosia, Cyprus
(Kambanellas, 2007)

Cyprus has a population of around 700,000 people but is visited by over 2.5 million
tourists a year. As a result, the different water resources in the area are almost fully
utilised. A greywater reuse scheme was started in 1997 as part of an initiative to
conserve water at the household level.

During the experimental study, measurements were taken and it was determined
that only 50% of the total potable water supply needed to be of drinking water
quality. A plan was then developed to use treated greywater to reduce the drinking
water demand. The first greywater systems were installed in 1997, and 7 additional
units were installed by the end of 1998. The experimental studies were carried out in
a hotel, a stadium and five houses (Kambanellas, 2007).

At the hotel, the mean per capital drinking water demand was about 40 litres per day.
The bathing water was used for irrigating gardens. At the stadium, the water used by
players for bathing amounted to 70% of the drinking water consumed. This
greywater was then used to water the lawns. For the five households (Figure 4), the
mean per capital drinking water consumption amounted to 122 litres per day, from
which dark greywater was about 33%. The dark greywater generated was used for
toilet flushing.

The cost of a household plant with capacity to treat 1 m3/day was approximately
CDN $2000 – the government currently pays over half of the money as a subsidy.
The drinking water savings were between 35 and 40% of total potable water supply.

28
Figure 4. Dark greywater reuse at the household level in Nicosia, Cyprus

3.1.6. Loughborough University, United Kingdom

(Surendran and Wheatley, 1998)

A model and prototype greywater treatment system for university residences were
constructed at Loughborough University (Surendran and Wheatley, 1998). The
model, used in the lab had a capacity of 75 litres and consisted of four stages, i.e. (i)
balancing flow and buffering peak mass loads (ii) solid separation and digestion (iii)
aerated bio-filter to remove organics, and (iv) deep bed slow filtration to generate
near potable quality. It operated for 200 days without any maintenance or
disinfection. Prior to the lab experiment, a survey was conducted to determine
people’s perceptions and it revealed that as many as 96% of customers would
accept greywater use for toilet flushing. The dissenting 4% expressed concern about
the purity and safety of recycled greywater and this prevented their acceptance.
During lab experimentation, the cost of the prototype plant arose as the major
concern.

The prototype, which was based on the lab model, was built to flush toilets used by
33 students with greywater and rainwater. Greywater for flushing 4 toilets was
2 rd
collected from 16 wash basins, 2 baths, 2 showers and about /3 of the water
29
discharged from a washing machine. The treatment processes comprise 4 of the 5
stages listed below while the fifth stage was optional.

Stage 1: 1400-litre balancing tank with a filter.

Stage 2: anaerobic solids treatment tank with large pore size.
Stage 3: aerated bioreactor with large pore size foam and beads. The
aeration used 2.4 l/min of coarse air bubbles.
Stage 4: active slow filter with small pore size reticulated foam. The
tertiary treatment phase was a deep slow filter that used 100
mm of 20 ppi foam over 700 mm of 45 ppi foam cartridges. The
system operated for approximately a year without problems.
Stage 5 (optional): activated carbon stage (for potable water quality).

Treated water was collected into two storage tanks; a low-level tank (700 litres)
attached to the treatment plant and a high level tank 500 litres) connected to the 4
toilets. The low-level tank was equipped with a timer to initiate pumping of treated
greywater to the high-level tank. Excess water was returned to the low-level tank via
a return pipe. A standby mains water supply was connected to the high level tank to
ensure adequate water supply when the amount of treated greywater was insufficient
for reuse. Water usage and some water quality determinants were regularly
monitored by means of flow meters and on-line monitors.

Twelve months of operation demonstrated that the treated water met the mandatory
limits of both EC and UK bathing water quality criteria in terms of turbidity, BOD5 and
faecal coliform. Odour problems or sludge blockages were not experienced
(Surendran and Wheatley, 1998). The unit was evaluated to have a payback period
of 8-9 years and a life-span of 20 years.

3.1.7. Annecy Residential Building, France

(Lazarova, 2001)

A full-scale greywater recycling scheme was set-up in a residential building with 64

apartments in Annecy, France (Lazarova, 2001). Forty of these apartments

30
(approximately 120 users) reuse greywater. Light and dark greywater is collected
from washing machines, baths, showers, wash basins, kitchen sinks and
dishwashers and treated using a membrane bioreactor (MBR) which undertakes
biological treatment followed by ultra-filtration. The collected greywater accounts for
approximately 50-70% of the total water use within the 40 apartments. Excess
recycled greywater water is discharged into the sewer or used for landscape
irrigation.

Water quality analysis showed that the dark greywater contained high concentrations
of organic matter, comparable to conventional urban wastewater but with a higher
fraction of biodegradable and soluble organics. It contained less suspended solids
and nitrogen but more phosphorus. Bacterial content was also high – up to 6-7 log
units of total coliform, faecal coliform, streptococci and E. coli. Consequently, MBR
treatment appeared to be a highly appropriate technical solution for the combined
shades of recycled greywater, because it produced a high quality effluent (fully
disinfected) and was operationally reliable. However, it remains one of the most
expensive treatment alternatives for water reuse, particularly in small installations
(<75 m3/d) such as was employed in this installation. The annualised capital and
operational cost was estimated at €3/m3 (Lazarova, 2001). This cost dropped to €1.7
/m3 for greywater treatment plants of up to 300 m3/d capacity which can serve
installations serving more than 500 inhabitants.

3.1.8. The Millennium Dome, London, United Kingdom

(Hills et al., 2001)

The largest in-building recycling scheme in the UK, known as the “Water cycle”, was
developed by Thames Water at the Millennium Dome (Hills et al., 2001). To reduce
the potable water requirement at the Dome, the recycling scheme treated greywater,
rainwater and ground water from site to flush all of the toilets and urinals on site (646
toilets and 191 urinals). The recycling plant had a capacity of 500 m3/d and served
6.5 million visitors in the year 2000.

Rainwater, which is the least polluted of the 3 water sources, from the Dome’s roof is

31
collected in specially designed hoppers which direct the roof run-off into the surface
water drainage system and treats it through a reed-bed system. The effluent from the
reed-bed is of a very high quality. Greywater from washbasins inside the Dome is
treated using a biologically aerated filter (BAF), followed by membrane filtration. The
BAF provides a compact and reliable treatment system for the reduction of BOD, SS
and microbiological contaminants from the greywater. Rising groundwater from an
aquifer beneath the Dome makes up the required flushing volume.

Preliminary tests revealed that the groundwater under the Dome is heavily
contaminated and brackish, so Granular Activated Carbon (GAC) and membrane
filtration were used to remove the organic contaminants and salt from the ground
water. Ultra-filtration membranes remove particulate matter and bacteria from the
influent. Microbial analysis showed 100% removal of both total coliform and E. Coli.
The reverse osmosis plant worked efficiently throughout the year with no cleaning of
the membranes necessary due to the efficiency of the ultra-filtration pre-treatment
(Smith et al., 2001).

Overall, the scheme provided recycled water for 55% of the Dome’s water
requirements during the year 2000. Greywater only made up 10% of the recycled
water requirement. This was because water was collected only from the washbasins
(i.e. not from kitchens, showers, etc.) and as water efficient taps were also used,
volumes of greywater collected were low. The major source of recycled water was
from groundwater (71%) with rainwater contributing 19% (Hills et al., 2001). A survey
carried out on a sample of visitors to the Dome showed positive results about the
recycled water used for toilet flushing (Hills et al., 2001).

3.1.9. Irvine Ranch Water District, California, USA

(Lewinger and Young, 1988)

The Irvine Ranch Water District, IRWD in California is a full service water and sewer
agency serving approximately 120 square miles and a population of about 138,000
people (year 2000). In the mid-1960s, the IRWD maintained a dual system which
provided reclaimed water for irrigation uses (Lewinger and Young, 1988 and Young

32
et al., 1994). The reclaimed water was expected to contain less than 2.2 coliform per
100 ml and was thus classified as Type 1 or Class A of Title 22 of the California
Administrative Code.

In 1987, with the planned development of high rise offices in the area, IRWD began
to investigate the feasibility of using reclaimed water in commercial buildings for non-
potable uses (Lewinger and Young, 1988). It was further estimated that 70-90% of
the total water used could be reclaimed water if employed for toilet and urinal
flushing and landscape irrigation (Young et al., 1994). A significant proportion of the
unused recycled water went to cooling tower operations.

In 1991, Irvine was the first district in the USA to obtain health department permits
for the use of greywater in interior spaces such as for toilet flushing (Young et al.,
1994). As a result, Irvine was the first city to use its reclaimed water for toilet-flushing
on a large scale (Young et al., 1994). Initially, greywater was used in two high-rise
buildings but by the late 1990s, the scheme was extended to two more 20-strorey,
high-rise and two low-rise buildings with five additional high-rise towers awaiting dual
service.

A 66 000 m3/d reclamation plant was constructed to provide treated greywater

(Young et al., 1994). Greywater was treated by biological oxidation, in-line chemical
coagulation and dual media filtration followed by disinfection. It was ensured that all
the processes met the requirements of the State of California Department of Health
Services Wastewater Reclamation Criteria (Lewinger and Young, 1998).

Results from the operation showed potable water demand drop in the high-rise
developments by 75%. For new buildings over seven storeys, the additional cost of
providing a dual system added only 9% to the cost of plumbing (IRWD, 2006). The
life-cycle cost of supplying greywater to at least half of the high-rise towers in the
districts was less than purchasing and distributing potable water over a 50 year
period (Lewinger and Young, 1988).

33
3.1.10. Casa del Agua, Tucson, Arizona, USA
(Karpiscak et al., 2001)

Casa del Agua is a Tucson residence that was retrofitted in 1985 with water-
conserving fixtures and reuse technologies, and landscaped with drought tolerant
plants. It is an occupied residence that is also an educational project designed to
facilitate research and to test domestic water use and conservation strategies, and is
open to the public during scheduled hours. Modifications included retrofitting existing
landscapes and enlarging the rooftop to collect and harvest rainwater; separating
blackwater and greywater drains; installing meters, low water-use appliances and
fixtures; and an approximately 22 litre underground sump for rainwater and
greywater collection. A public information centre was also developed. The
construction cost of the greywater treatment and distribution system was about
US$1500.

A filter was fitted over the greywater drain where it enters the sump to remove lint
and hair before the water was pumped to other components of the recycling system.
The sump filled to a level that activated a float switch and then greywater was
pumped through an underground drip irrigation system to the landscape or for use in
toilet flushing

Over the 13-plus years of actual operation, research results have indicated that large
reductions in water use are possible using water-saving devices and/or harvesting
and reusing rainwater and greywater respectively. Casa achieved a 47% reduction in
municipal potable water use compared to a typical Tucson residence. Overall, water
use comprised of harvested rainwater (10%), recycled greywater (20%), and
municipal potable water (70%).

3.1.11. Japan

Greywater reuse is also practiced in Japan on a scale that ranges from the simple
residential use of untreated greywater for toilet flushing to complex systems in office
blocks. The simple residential use of untreated greywater for toilet flushing is

34
illustrated in Figure 5. This technology is popular in Japan and installed in many
Japanese homes, as well as in commercial areas. This system incorporates a hand
basin at the top of the cistern, with a tap for hand washing. The tap automatically and
simultaneously operates with each toilet/urinal flush refilling the toilet cistern while
permitting the washing of hands. While this system is very simple, it nevertheless
promotes the conservation of water for residential use. In applications where the
greywater has been captured from other household sources for toilet flushing,
unpleasant odors and discoloration of the toilet bowl were reported (CSBE, 2003).
The Japanese government does not provide incentives for household residents to
implement greywater systems in their own living spaces. Nevertheless, many people
choose to implement them in urban areas because water costs are very high.

Figure 5. A simple untreated greywater reuse system in Tokyo

On the other hand, the Japanese government is making an effort to implement

greywater technology in more extensive urban commercial uses. In the capital city,
Tokyo, greywater reuse is mandatory for buildings with an area over 30,000 m2 or
with potential reuse of 100 m3/day. In order to offset the costs associated with
construction, the Japanese Ministry of Construction provides subsidies of up to 50
percent of the capital costs. The government also assists in connecting commercial
greywater systems to the public sewerage system. Therefore, while residential
greywater use is minor in Japan, commercial greywater use is very extensive (Chung
and White, 2010).

35
3.1.12. Taiwan
(Chin-Jung et al., 2005)

A pilot-scale, compact and inexpensive electro-coagulation process with a capacity

of 28 m3/day was developed at the National Taiwan University, Taipei. The pilot-
scale system was intended at using domestic greywater for human non-contact
requirements (including toilet flushing). The total cost of the on-site domestic
greywater reuse system was U.S. $0.27/m3 – below the potable water rate and the
cost of a regional dual water system. Moreover, the treatment facility required an
area of just 8 m2. Experimental results from this system supported the feasibility of
installing further on-site greywater reuse systems in high-rise buildings.

3.1.13. Vehicle washing in some South African cities

(Ewasha, 2011)

Several vehicle wash services in Durban (e.g. La Mercy Airport), Port Elizabeth,
George, Johannesburg (e.g. Jet Park) and Cape Town (e.g. at the airport) employ a
system for reusing water previously used for washing (Figure 6). The system collects
the used vehicle wash water and pumps it through a series of bioreactors which use
a natural, biological process to clean the water of impurities such as soap, grease
and dirt. No chemicals or filters are used. Once the treatment process has been
completed, the water is returned to the wash bay ready for re-use in the washing of
the vehicles. Any loss in used water, due to factors such as evaporation or spray
mist, is replenished using stored rainwater before using the municipal water supply.
It is claimed that municipal potable water usage using this system has been reduced
by up to 90% with a commensurate reduction in the amount of wash bay runoff being
discharged.

36
Figure 6. (Above) A schematic of the Ewasha greywater reuse technology.
(Below) One of the vehicle wash services in Durban

3.1.14. Green’s Cool Early Learning Centre, Pinelands, South Africa

(Water Rhapsody Conservation Systems, 2011)

In 2008, a R25 million corporate daycare centre – the Green’s Cool Early Learning
Centre, was built for financial services group, Old Mutual. The centre with floor area
of 21442 m² can accommodate up to 75 babies and 300 pre-school children of Old
Mutual’s employees who work within sight and walking distance of the company’s
Pinelands head office in the City of Cape Town. Several environmental friendly
technologies were implemented in the facility including the installation of a system
which reuses greywater from washbasins to flush the centre’s toilets (Figure 7). After
collection of greywater, the reuse system employs a simple coarse filter and

37
chlorination system for treatment. Thereafter, the treated greywater is stored in
submerged tanks housing pumps which convey the greywater from the tanks to the
toilet bowls when the pumps are activated within the toilet cubicle.

Figure 7. (Left) One of the centre’s toilets reusing greywater for flushing.
(Right) Several submerged filters and tanks that house the pumps that convey
greywater to the toilet bowls

3.1.15. Featherbrook Estate, Gauteng, South Africa

(Aquacycle, 2009)

In one of the residential units within the Featherbrook Estate on Gauteng’s West
Rand, there is a greywater reuse system that recycles light greywater for non-
potable water requirements such as toilet flushing, garden irrigation and car washing.
The system which is developed in Europe is called Pontos AquaCycle® (Figure 8).

The first treatment stage of the greywater treatment unit is pre-filtration. Pre-filtration
involves the separation of larger particles such as hair and textile fragments from the
greywater stream. These sediments are then washed into the sewer. The next
process is a 2-fold biological treatment process where in the main and secondary
treatment chambers, sediments in the greywater are decomposed by bio-cultures.
The organic sediments which are produced during this process are regularly sucked
out from the chambers and diverted into the sewer. The resultant greywater is then
pumped to the next station in three hour intervals. A UV lamp disinfects the

38
greywater as it flows into the storage chamber and should the supply in the storage
unit drop below a certain level, municipal potable water will automatically be fed into
this chamber to ensure there is enough supply for flushing toilets. The system is built
as closed up compartments and the treatment processes are not typically visible to
the by-stander. This system is also automated with on-board software.

Figure 8. The Pontos greywater treatment system

3.2. Controversial/failed case studies

3.2.1. Victoria University of Technology, Melbourne, Australia

(Christova-Boal et al., 1996)

A social survey conducted in Melbourne showed that people were interested in

reusing greywater from the bathroom and laundry and had a strong preference to

39
use the effluent for garden irrigation. However, most of these people would only
consider a greywater reuse system if the payback period was between 2-4 years. In
response, a sampling and testing programme (to analyze some physical, chemical
and microbiological characteristics of bathroom and laundry greywater) was
undertaken.

Four experimental sites were selected. Three houses were retrofitted to reuse
greywater for garden watering and toilet flushing while one house was newly built
with a greywater system incorporated in the building plans. At the experimental sites,
removal of suspended materials was achieved using a three-stage filter system:
 Stage 1 – a strainer (pre-filter) in the laundry, shower or bath drain to remove
large sized materials;
 Stage 2 – a mesh filter installed in the collection tanks to collect hair, soap
particles, lint and some entrapped body fats; and
 Stage 3 – a fine filter on the supply line to the irrigation pipes or toilet cistern for
precipitates and settled materials.

A number of difficulties were encountered when the greywater systems were

retrofitted. One of which was that the greywater sources were located very close to
the ground level, thus making gravity flow of the greywater into the collection tanks
difficult. Collection tanks thus had to be installed below ground level.

Lessons learnt
i. Inclusion of the greywater system in the construction of buildings is imperative in
order to optimise costs and to implement efficient and sustainable systems.
Retrofitting of the greywater system naturally creates problems as it tends to
obstruct or occupy spaces not originally design for it. Cost has been highlighted
as one of the major barriers to a wider uptake of greywater recycling systems
(Mustow et al., 1997). The costs associated with greywater recycling in different
locations are difficult to compare as they depend on the quality of the recycled
water and the use to which it may be put. They also depend on which costs are
considered in the life cycle analysis carried out, i.e. capital, operational and
externalities (e.g. greenhouse gas production)

40
ii. Long pay-back periods tend to infer non-profitability, and thus tend to dampen
public and decision-makers’ interests in greywater reuse. In the survey conducted
by Christova-Boal et al. (1996), most respondents preferred a payback period of
between 2-4 years.
iii. The operating costs of treating the greywater were considered high because a
significant amount of money was spent on disposable filters.
iv. The analyses of bathroom and laundry greywater showed high levels of sodium,
zinc, aluminium and, by inference, carbonate which are detrimental to soil
conditions. The initial trials using 0.1 mm mesh filters and 0.11 mm disc spacings
did not work as the filters got clogged almost immediately. Satisfactory
performance was achieved using the next larger size of filters (i.e. 0.2 mm mesh
filters and 0.17 mm disc spacing).
v. Tanks containing greywater generally provided an ideal breeding ground for
pathogenic microorganisms and mosquitoes, and were a source of odour. Hence,
tanks need to be regularly maintained, disinfected, ventilated, child-proof and
comply with local health and plumbing by-laws. Physically, tanks require space
which may either be limited or unavailable (in retrofitted situations), and their
optimum location on site may interfere with existing services. Above-ground tanks
located exterior to the dwelling may have undesirable visual impacts and hence
tanks may be located beneath a dwelling or below ground surface. In addition to
the above, tanks must be accessible for cleaning.

3.2.2. Linacre College, Oxford, United Kingdom

Linacre College houses the first domestic water recycling scheme in the UK. A
student residence housing 23 occupants was built in 1995 using “environmental
friendly” or recycled materials in order to cut down on energy and water demand.
One of the conservation aspects was the reuse of greywater for toilet flushing. A
survey conducted prior to the project showed that 40% of the occupants were
concerned about the potential odour and smell of the treated water but would
consent to the plan if these were eliminated.

The first scheme comprised a bag filter and a depth filter. Due to severe problems,

41
however, the plant operated for only two days. Subsequently, Anglian water services
Ltd, Huntingdon, undertook a series of process selection trails (Murrer and Wards,
1997) to identify a suitable system for the scheme, and a number of sand filters and
membranes were tested. A trail house with a selected process was identified and
used in investigating the cause of the earlier problems. This led to the second stage
of the Linacre scheme where the greywater was treated using a depth filter and a
membrane. Greywater from baths, showers and hand basins was collected in a tank
and filtered through a 4 inch diameter sand filter (Murrer and Ward, 1997). This was
followed by further filtration using a hollow fibre ultra-filtration membrane with pore
size of 0.01m. The filtered effluent was collected into a tank located in the loft of the
house. The effluent in the tank may be topped up with potable water supply from the
mains when necessary in order to supply enough water for toilet flushing. The
effluent was then disinfected with chlorine prior to use. Some of the effluent from the
ultra-filtration membrane was used to backwash the sand filter. A 5 log reduction in
bacteria was attained through this treatment train and viruses were not detected in
the effluent.

After a few months of operation, the system suffered some operational difficulties.
Operation and maintenance costs were found to be high due to excessive
membrane fouling resulting in low flux (Ward, 2000). Raw greywater was partially
digested under anaerobic conditions in the lengthy collection network resulting in
poor permeate quality and odour problems from the network. Consequently, a further
process modification was done and this time a biological system (Ward, 2000) was
incorporated. The process scheme now comprises a bioreactor followed by a sand
filter, an activated carbon column and chemical disinfection. Further development of
the membrane cleaning procedure was undertaken to reduce membrane fouling from
fats and other organic material in the greywater treatment system. The system has
been effectively working since then.

Lessons Learnt
i. Perception surveys of the consumers and the local authority was very important
before the implementation of the reuse system.
ii. Public enlightenment campaigns incorporating the concerns raised, helped to

42
 educate consumers on the benefits of the reuse system. Positive community
attitudes towards recycled water use have been identified as a key component of
the success of a water reuse project (Po et al., 2003).
iii. Prior to the choosing of water reuse treatment equipment, project managers
should talk extensively to manufactures about the technical issues and processes
involved. This is to ensure that the components are compatible and can
synergistically work as a system. The challenges of using smaller membrane
sizes resulting in membrane fouling, poor permeate quality, and odour problems
may have been avoided in the above scheme.
iv. Realistic timelines should also be negotiated and understood by the engineers,
architects, project managers, residents and municipal staff.

3.2.3. Water Dynamics systems, various locations in UK

(Sayers, 1998)

A two-year project was carried out by Environmental Agency (EA) to assess the
feasibility of single household greywater systems. Water consumption, cost savings,
water quality, and user perceptions of the reuse system were evaluated. Ten houses
were retrofitted with Water Dynamics’ recycling systems, in order to recycle
greywater from hand basins, baths and showers for toilet flushing. Water meter
readings, along with greywater samples from the storage units and the toilet cisterns
were taken on monthly basis for analyses.

After the first year of operation, cost savings from 5.2-30.6% were realised for the 10
houses. In the second year, savings of 5.3-35.9% where realised with the number of
houses involved in the study dropping to 8 (Sayers, 1998). Acceptable water quality
in terms of pH (6-8) and phosphorus (around 1 mg/l) were realised. Ammonia
averaged <8 mg/l, but on occasions, rose to 40 mg/l thus resulting in odour problems
(Sayers, 1998). The following operational concerns were raised during the study:
 The need for frequent cleaning of the filters due to blocking;
 Pump failures occurred often times and hence, the potable water supply was
used for toilet flushing during those times;
 Chlorine dosing using a bromine-based disinfectant led to some odour;

43
 Staining of toilet bowls led to the more frequent use of cleaning products;
 There was a building-up of sediments in the toilet cistern;

Improvement to the system design, such as the location of the disinfectant and
alarms (in case of blockages or low levels of disinfectant) were suggested by the
residents. Residents generally found the appearance of the treated greywater to be
visually acceptable though the retrofitted greywater reuse infrastructure was visually
unattractive. Payback periods were calculated based on a range of water and
sewerage charges and household occupancy and excluding running and
replacement costs. The most economical payback period was 13 years in case of a
4 person household and the most uneconomic at 138 years in case of a single
person household.

Lessons Learnt
i. The accuracy of modelling experiments was critical in determining actual
greywater generation and toilet flushing flows. An accurate estimation of these
flows would have prevented a significant number of the breakdowns experienced
during operation;
ii. Continual monitoring and education of residents on the greywater units was
critical to sustainability. In many instances, residents “forgot” about the systems
and hence problems occurred;
iii. The economical aspect (specifically payback period in this project) of
implementing a greywater reuse project is critical in evaluating the viability of
greywater reuse.

3.2.4. Quayside Village Vancouver, British Columbia, Canada

Quayside village (QV) is a co-housing community located in the City of North

Vancouver British Columbia. As a multi-agency supported demonstration project,
Quayside’s greywater system had to be reviewed and discussed with a number of
agencies. Government municipal staff expressed concern about possible liability for
water-related sickness. For this reason, a conservative greywater reuse system with
several backup features was permitted, with treated greywater to be used for toilet

44
flushing. The reuse system included the following components (Figure 9):
 A septic tank to remove coarse solids and grease/oil;
 A biofilter with recirculation back to the septic tank inlet;
 A slow sand filter to remove solids;
 Ozone generator and contact tank which was subsequently replaced by
chlorination;
 A slow sand filter for automated back-washing, and
 A storage tank.

Figure 9. Quayside Village greywater reuse System

Although the system operated for over three years, there were a number of
equipment failures that interfered with the system being able to meet the regulatory
requirement of six continuous months of operation. One of the key problems initially
identified was the reliance on ozone as the sole means of disinfection, compounded
by the lack of adequate ventilation for the ozone gas residue.

The following remedial measures were then implemented:

 The ozone generator contact tank was removed and replaced with a chlorination
system. This eliminated the problem with the ozone gas residue and provided a
chlorine residual to control the re-growth of bacteria
 The cloth fabric which was intended to assist in removing colloidal particles was
removed from the septic tank. This was because the structure supporting the
fabric in the tank collapsed and blocked the outlet.

45
Lessons Learnt
System design and function should be resolved with the relevant authorities before
reuse equipment are purchased and the system installed. This is because
municipalities would generally require a conservative system that will be robust
enough to prevent risks to public health and safety.

3.2.5. Toronto Healthy House, Ontario, Canada

The Toronto Healthy House project resulted from a Canada wide Health Housing
Design Competition. Two residences located next to one another were not
connected to the municipal potable water supply and sewage infrastructure, and
were situated on small stands (approximately 6 m by 22 m in area). The dwellings
relied on harvesting rainwater for potable water requirements, and reuse water for all
other domestic water needs (i.e. toilet flushing, laundry, bath/showers and irrigation).
Blackwater and greywater were collected and treated for reuse. The treatment
process consisted of the following components which are similar to the Quayside
Village greywater reuse system discussed above:
 A 3 000 litre septic tank which was divided into two unequal (2/3,1/3)
compartments. The first compartment was designed to remove coarse solids and
grease, while the second was equipped with hanging filter cloths intended to
remove colloidal solids;
 Biofilter with recirculation back to the septic tank inlet;
 Roughing filter to remove coarse biosolids;
 Slow sand filter to remove fine particles (both the roughing and slow sand filters
are automatically back-washed;
 In line ozone injection, followed by a contact tank;
 Storage tank.

Any wastewater that is in excess of the reuse requirement of the household is

discharged to a gravel bed situated in the front yard of the building.

A three component filter (roughing filter, slow sand filter and activated carbon filter)
was originally installed but was decommissioned and replaced with a separate

46
roughing filter and slow sand filter due to problems experienced with filter clogging.
Online data for both the potable and reuse system was collected by an independent
agency from November 2000. Parameters monitored included microbiological (Total
Coliforms, E. coli and background bacteria) and chemical (nitrate, BOD, TSS, TDS,
sodium, chlorides, phosphates and ammonia). Although some reuse water qualities
(i.e. BOD, TSS and turbidity) consistently met the relevant standards, the Total
Coliform criteria were not met during certain times and heterotrophic plate counts
were often elevated, indicating bacterial regrowth in the reuse storage tank and
distribution system. Regrowth can include “opportunistic pathogens” such as strains
of pseudomonas aeruginosa, and Acinetobacter spp.. The potential for regrowth is of
particular concern where the water is being sprayed and potentially inhaled as will
occur when using treated greywater for showers/baths and toilet flushing. Strains of
Klebsiella pneumoniae and Legionella pneumophila if inhaled as aerosols can cause
severe illness. Water temperatures of 30 to 50oC are favourable for the growth of
Legionella pneumophila. Another concern with the existing treatment system was
that ozone was being released into the residence posing a health hazard to the
occupants.

The following remedial measures were recommended to improve system

performance and address the problems observed with the Toronto Health House
reuse water system:
 An ozone sensor and alarm to be installed, and consideration given to modifying
the ventilation of the equipment space to ensure the ozone is destroyed and the
gas is ventilated outside of the building.
 That either a secondary chlorination or ultraviolet disinfection be added to both
the potable and reuse water treatment systems to inhibit bacterial regrowth within
the storage and distribution systems. The provincial health agency preferred to
have a minimum 1 mg /l chlorine residual maintained within the distribution
system.

Lessons learnt
Careful consideration must be given to ensure that ozone residue is allowed access
to proper ventilation, and that consideration is given to controlling regrowth of

47
bacteria within the storage and distribution systems. One method of achieving this is
to maintain an adequate residual chloride level within the treated water storage tank.

3.2.6. The Conservation Co-operative Apartment Building, Ontario

Conservation co-operative is a 4 storey, 84 unit apartment building located in the

Sandy hill district of the City of Ottawa. The tenants are committed to providing
“green” alternatives within an environmentally friendly building thus reducing the
consumption of energy, water and waste to levels significantly lower than
conventional households. Constructed in 1995, the project incorporates water
conserving plumbing fixtures that have resulted in a normalized water use per
apartment of 390l/day compared to a typical apartment’s water consumption of
530l/day in the Ottawa area. Bathrooms in 8 of the 84 apartments were constructed
with dual plumbing systems. The plumbing systems allowed the bathrooms to
operate using both municipal potable water and reuse greywater for toilet flushing.
The primary source of greywater is the bathtubs.

Discussions were held with the Ministry and City officials to develop treatment
criteria. The criteria for the design of the treatment systems were established and
accepted by the Regional Health Department on the understanding that this was an
experimental system for water reuse strictly for toilet flushing. The average daily
water use was 640 l/day for toilet flushing, 1300 l for baths/showers and 700 l/day for
other uses (there were no laundry facilities in individual apartments).

The greywater reuse system was completed and commissioned for use in August of
1999. It consisted of the following components:
i. Basket screens (1 mm mesh) to trap hair, lint and other large particles. Sodium
hypochlorite packs were placed in the screening baskets to control odours and
filter fouling;
ii. Equalization tanks (440 l) to remove floatable oils ,scum and settleable solids, as
well as provide initial disinfection. Accumulated solid scum was automatically
discharged into the sewer after each treatment cycle was complete;

48
iii. A pump to transfer effluent from the equalization tanks and through a multi-media
pressure filter;
iv. Upflow multi-media pressure automatic-backwash filter to remove particulate
material. These types of filters are more commonly used in potable water
treatment systems and do not remove BOD;
v. Ozone is added to the filtered water prior to discharge into the treated water tank;
vi. A treated water tank (600 l);
vii. A distribution pump that is activated by a drop in pressure (i.e. toilet flushing)
within the distribution system.

By late September 1999, the filter media had to be replaced, and by mid-October,
one of the system pumps had failed and the system was down for two weeks until
the pump was replaced. A valve and pump failure in November shut the system
down until early December 1999. By March 2000, the treatment system was shut
down and the toilets to the eight units were once again connected to the municipal
potable water mains. This action was taken in response to extensive complaints from
the residents of the 8 apartment units regarding problems with odour and rapid scum
accumulation in the toilets, and an accident in which ozone release from the
treatment facility caused injury to the maintenance supervisor.

An independent review of the treatment system noted the greywater had a significant
biochemical oxygen demand (BOD5) of 130 mg /l that had not been taken into
consideration in the treatment process design. As a result, no biological treatment
had been provided for and the filtered greywater rapidly became anaerobic,
producing black, foul-smelling reuse water that was being reused for flushing the
toilets. Furthermore, the toilets for the 8 apartments were subjected to significant
water-hammer effects as a result of the transfer pump and temporary nature of the
pilot installation, resulting in loud banging noises and vibrations that were extremely
disconcerting to the residents.

The following remedial measures were recommended to improve system

performance and address the problems observed:

49
 Add a biological treatment component to reduce the BOD concentration to less
than 10 mg/l;
 Add a pressure tank to the distribution system to improve water supply to the
toilets;
 Remove the ozone system and replace it with either a second chlorination or
ultraviolet disinfection system.

Lessons learnt
The project demonstrated that significant operating and maintenance problems can
be experienced with greywater reuse if (i) wastewater characterization is not
considered in the design, and (ii) appropriate components are not incorporated in the
treatment system to remove BOD. Greywater must be treated if it is to be stored for
any significant period of time, or if it is to be distributed through plumbing for any
indoor application.

3.2.7. The Limpopo Parliamentary Village, Polokwane, South Africa

Dingilizwe (2010).

The Limpopo Parliamentary Village in Bendor Park, Polokwane is situated on an 18

hectare plot. It comprises forty-four 3 and 4 bedroom housing units and other social
amenities including a social club, tennis courts and volleyball courts. The village’s
wastewater disposal system was designed such that all the greywater (including
kitchen water) is recycled. The greywater is initially conveyed to a tank from where it
is then pumped to the irrigation system that serves the gardens and open spaces.
The recycled water undergoes only sedimentation and oil separation which take
place within the tank. Rainwater is also harvested from roofs and conveyed to the
tank.

Since commissioning, residents have complained of unpleasant odours emanating

from the system and the recycled greywater which is used to irrigate the gardens. A
preliminary investigation was carried out in May 2010 to address these complaints
and some of the findings of the investigation included:

50
i. The tank volume was about 50 m3 thus resulting in an average greywater
retention time of about 64 hours. Considering the minimal treatment carried out
on the greywater, the prolonged retention time encouraged deterioration of the
greywater quality;
ii. The above point was compounded by the fact that the tank was closed and thus,
promoted anaerobic conditions which are conducive to pathogenic growth and
consequently, higher BOD;
iii. A sprinkler system was employed for irrigation. This was inappropriate
considering the potential of inhaling contaminated greywater molecules that
become airborne. This was also one of the likely causes of the smells that the
residents complained about. Sub-surface or drip irrigation technologies would
have provided a better and safer technology for irrigation;

These findings have been presented to the relevant Water Supply Provider/authority.

3.3. Pertinent issues from the case studies

 Government subsidies have proven positive in encouraging individuals,

communities or institutions to embrace greywater reuse systems (Kambanellas,
2007 and Chung and White, 2010) as subsidies typically lower the cost of
greywater reuse and often times cause them to be lower than potable water.
 Long pay-back periods tend to infer non-profitability, and thus tend to dampen
public and decision-makers’ interests in greywater reuse. The case studies
reviewed indicate that on average, greywater systems had a payback period of
between 8-14 years (Sayers, 1998; Surendran and Wheatley, 1998; March et al.,
2004; and Ghisi and Ferreira, 2007) with preference for between 2-4 years
amongst potential respondents in Melbourne, Australia (Christova-Boal et al.,
1996).
 Large housing developments have provided more tangible economic benefits
than smaller ones as a result of economies-of-scale
 The most economical applications for many greywater systems were in
combination with rainwater.
 The recycling of greywater needs to be done in such a way as to avoid the

51
 building up of impurities. The use of a final, polishing filter in the treatment plant
would then seem to be an essential component of the treatment plant.
 The technologies used to treat greywater for reuse must be effective in dealing
with organic material, solids and pathogens. The different greywater recycling
schemes reported to date, have however achieved very different performances.
Simple technologies and sand filters have been shown to have only a limited
effect on greywater, whereas membranes have been reported to provide good
solids removal but cannot efficiently tackle the organic component. Micro-
organism removal was achieved in schemes that included a disinfection stage or
membrane bioreactor.
 Disinfection of greywater for utilization in flushing toilets and urinals was stressed
in order to eliminate pathogenic organisms which have potential to impact
negatively on public health if ingested.

52
 4. INTERNATIONAL AND LOCAL REVIEW OF REGULATIONS AND
GUIDELINES REGARDING GREYWATER REUSE

4.1. Introduction

It has been noted that the major barrier to the adoption of water reuse as a strategy
is the lack of regulations and/or guidelines for plumbing requirements for non-potable
water systems and reuse water quality (CMHC, 1997). Regulations for water reuse
are based on the necessity to protect human health and the environment and are
thus enacted and enforceable by government agencies while guidelines are not
enforceable, but are a compilation of best practice and can be used in the
development of a reuse program (USEPA and USAID, 2004).

In respect of protecting human health, regulations/guidelines generally attempt to

reduce the risks to public health due to greywater exposure, which may occur either
via inhalation, direct skin contact or ingestion of microorganisms (bacteria, protozoa
and viruses) and chemicals in household greywater. Exposure via ingestion can be
responsible for severe gastrointestinal illness. This is of particular concern for
susceptible individuals, such as infants, the elderly, and those that have
compromised immune systems, for whom the effects may be more severe, chronic
(e.g., kidney damage), or even fatal. Microbiological hazards have been identified as
the greatest source of risk to human health from the use of reclaimed water
(WGHRW, 2007). Effective treatment can produce reclaimed water that is virtually
free of disease-causing microorganisms. There are no negative health impacts
expected from chemicals in household reclaimed water used only for toilet and urinal
flushing.

In respect of protecting the environment, regulations/guidelines guard against the

short- and long-term deleterious impacts on activities such as irrigation and effluent
discharge into natural water courses.

Regulations and guidelines relating to greywater reuse vary from one country to
another and these are briefly appraised in the following sections:

53
4.2. Review of regulations and/or guidelines regarding greywater reuse in
other countries

4.2.1. USA

There are no federal regulations directly governing water reuse practices in the USA.
Water reuse regulations and guidelines have, however, been developed by many
individual states. As of November 2002, 25 states had adopted regulations regarding
the reuse of reclaimed water, 16 states had guidelines or design standards, and 9
states had no regulations or guidelines. In states with no specific regulations or
guidelines on water reuse, programs may still be permitted on a case-by-case basis
(USEPA and USAID, 2004).

States that have water reuse regulations or guidelines have set standards for
reclaimed water quality and/or specified minimum treatment requirements.
Generally, where unrestricted public exposure (such as toilet flushing) is likely in the
reuse application, wastewater must be treated to a high degree prior to its
application. Where exposure is not likely, however, a lower level of treatment is
usually accepted. The most common parameters for which water quality limits are
imposed are biochemical oxygen demand (BOD), total suspended solids (TSS), and
total or faecal coliform counts (USEPA and USAID, 2004).

States with regulations or guidelines pertaining to the use of reclaimed water for
toilet flushing (i.e. unrestricted urban reuse) are Arizona, California, Florida, Hawaii,
Massachusetts, New Jersey, North Carolina, Texas, Utah, and Washington. Table 7
presents greywater treatment and quality requirements for these different states.

54
Table 7. Greywater quality and treatment requirements for different states for
unrestricted urban reuse
(USEPA and USAID, 2004)

(1)
NS – Not specified by state regulations

4.2.2. Australia

The EPHC et al., (2006) guidelines is one of the most recent guidelines on greywater
reuse to be published in Australia. This is against the back drop of different
guidelines which have been published by Australia’s different regions in the past. A
nationally consistent approach to the management of health and environmental risks
from water recycling requires high-level national guidance on risk assessment and
management. Such guidance is provided in the EPHC et al. (2006) guidelines in the
form of a risk management framework for beneficial and sustainable management of
water recycling systems. Although these guidelines are not mandatory and have no
formal legal status, their adoption provides a shared national objective, and at the
same time allows flexibility of response to different circumstances at regional and
local levels. All states and territories are therefore encouraged to adopt the
framework in the document. However, application of the framework may vary across
jurisdictions, depending on the arrangements for water and wastewater
management.

55
As mentioned above, a central feature of the EPHC et al. (2006) guidelines is a
generic risk management framework that can be applied to any system recycling
water from treated sewage, greywater and stormwater. The risk management
framework is used to develop a ‘risk management plan’ that describes the nature of
a recycled water system and how it should be operated and managed. An excerpt
from the EPHC et al. (2006) guidelines on the risk management approach to water
quality and use is presented below:

“A risk management approach involves identifying and managing risks in a proactive

way, rather than simply reacting when problems arise. In applying this approach to
water recycling, the first step is to look systematically at all the hazards in the
recycled water that could potentially affect human or environmental health (i.e. what
might happen and how?). Once the hazards are identified, the risk from each hazard
is assessed by estimating the likelihood that the event will happen and the
consequences if it did. That is, the risk assessment asks ‘How likely is it that
something will happen?’ and ‘How serious will it be if it does happen?’, and thus
provides a means to identify those hazards that represent significant risks for the
proposed end use. The next step is to identify preventive measures to control such
hazards, and to establish monitoring programs, to ensure that the preventive
measures operate effectively. The final step is to verify that the management system
consistently provides recycled water of a quality that is fit for the intended use (i.e. ‘fit
for purpose’).”

The framework for management of recycled water quality incorporates 12 elements.

Although listed as discrete components, these elements are interrelated, and each
supports the effectiveness of the others. Because most problems associated with
recycled water schemes are attributable to a combination of factors, the 12 elements
need to be addressed together to assure a safe and sustainable recycled water
supply. The 12 elements are organised within four general areas, as illustrated in
Figure 29, and listed below:
 Commitment to responsible use and management of recycled water. This
requires the development of a commitment to responsible use of recycled water
and to application of a preventive risk management approach to support this use.

56
 The commitment requires active participation of senior managers, and a
supportive organisational philosophy within agencies responsible for operating
and managing recycled water schemes;
 System analysis and management. This requires an understanding of the entire
recycled water system, the hazards and events that can compromise recycled
water quality, and the preventive measures and operational control necessary for
assuring safe and reliable use of recycled water;
 Supporting requirements. These include basic elements of good practice, such as
employee training, community involvement, research and development, validation
of process efficacy, and systems for documentation and reporting;
 Review. This includes evaluation and audit processes to ensure that the
management system is functioning satisfactorily. It also provides a basis for
review and continuous improvement.

Figure 29. Elements of the framework for management of recycled water

quality and use (EPHC et al. 2006)

The guidelines provide specific guidance for:

i. large-scale greywater to be used for (a) residential garden watering, car washing,
toilet flushing and clothes washing, (b) irrigation for urban recreational and open
space; agriculture and horticulture, (c) fire protection and fire fighting systems,

57
 and (d) industrial uses, including cooling water (from a human health
perspective); and
ii. greywater treated on-site for use in residential garden watering, car washing,
toilet flushing and clothes washing.

Table 8 presents an extract of treatment processes and on-site controls for toilet
flushing water quality

Table 8. An extract of treatment processes and on-site controls for toilet

flushing water quality

4.2.3. Japan

Japanese local and national governments have initiated numerous municipal and
industrial wastewater reuse projects since 1970. Estimates of water reused in urban
dwellings for toilet flushing ranges from 33 to 37%. An increasing need to incorporate
water reuse into traditional water supply practice led to revision of some of the
existing regulations and guidelines in the 1990s. For example, in Tokyo, greywater
recycling is mandatory for buildings with a floor area greater than 30 000 m2 or with a
potential reuse of greater than 100 m3/d. Japanese guidelines for domestic reuse of
greywater are similar to many other standards in terms of BOD and some physical
parameters (e.g. pH and turbidity) (an extract is shown in the Table below)
(Surendran and Wheatley, 1998).

58
Table 9. Japanese mandatory standards for greywater reuse
(Surendran and Wheatley, 1998)
Total E. coli Faecal coliforms BOD Turbidity CL2 pH
coliforms (cfu/100 (cfu/100 ml) (mg/l) (NTU) residual
(cfu/ 100 ml) (mg/l)
ml)
10 10 10 for any sample 10 5 - 6-9

4.2.4. European Union

The European Union (EU) drafted a directive to assimilate all existing European
regulations on water (Bontoux, 1998). The major problem encountered in the
assimilation was finding a uniform solution for all the EU member countries which
differ geographically, climatically as well as in availability of water sources. Although
greywater recycling for toilet flushing and fire fighting are emerging applications in
France and Spain, these countries have developed a regulatory framework around
agricultural reuse – which remains the major greywater reuse application. In 2000,
the Spanish government issued a draft of guidelines which include non-potable
urban reuse such as toilet flushing (see Table below). In Germany, greywater reuse
is not widely employed due to the inherent health risks. However, research towards
greywater treatment for in-building reuse has gained interest and has resulted in the
installation of some operating system on various sites. Guidelines for treated
greywater were introduced at a local level in Berlin (Nolde, 1999), with the key water
quality parameters shown in Table 10.

59
Table 10. Standards for wastewater reuse quality in the European Union
(Surendran and Wheatley, 1998; Nolde, 1999)
2
Total E. coli SS Faecal BOD Turbidity CL pH
coliforms (cfu/100 (mg/l) coliforms (mg/l) (NTU) residual
(cfu/ 100 ml) (cfu/100 ml) (mg/l)
ml)
Spain - 0 10 - - 2 - -

ECa 1000(m) - - 1000(m) - - - 6-9

bathing 500(g) 500(g)
water
standard
Germany 100(g) - - 10-500(g) 5(g)b 1-2(m) - 6-9
(g) 20(g) c 20
WHOd - - - 1000(m) - - - -
lawn 500(g)
irrigation
a
(g) = guideline; (m) = mandatory; = European Community; b = BOD7; c
= BOD5; d
= World Health Organization;

4.2.5. The United Kingdom

To meet the needs of the increasing number of recycling systems available in the
UK, the Building Services Research and Information Association (BSRIA) proposed
guidelines (Mustow et al. 1997) for greywater, stored rainwater and combined
greywater and rainwater reuse systems. The BSRIA guidelines adopted the same
guidelines for bacteriological quality as the USEPA (see Table below). The BSRIA
guidelines have since been reviewed. In 1999, new water supply regulations (WRAS,
1999) were introduced. These regulations recognized greywater and rainwater as
beneficial resources, made the identification of pipe work compulsory and rendered
illegal cross-connections between potable and non-potable supply pipes.

Table 11. UK quality standards for domestic greywater reuse

(Surendran and Wheatley, 1998)
Total Faecal BOD Turbidity CL2 pH
coliforms coliforms (mg/l) (NTU) residual
(cfu/ 100 ml) (cfu/100 ml) (mg/l)
UK bathing 1000(m) 1000(m) - 2 m(g) 1 - 6-9
water standarda 500(g) 500(g) m(m)
UK (BSRIA)f - 14 for any - - - -
sample 0 for
90% samples
a
= Bathing water standards suggested as appropriate for domestic water recycling;
f
= toilet flushing
60
4.2.6. Canada

Due to the risks to human health or the environment and the low cost for water in
Canada, pursuit of water reclamation has been slow. British Columbia was the first
Canadian province to have enacted a reclaimed water standard for a variety of
applications (Government of British Columbia, 1999). The Atlantic Canada
Standards and Guidelines Manual for the Collection, Treatment and Disposal of
Sanitary Sewage include a chapter on reclaimed water use, with a focus on irrigation
(Environment Canada, 2006). Other provinces have typically used a case-by-case
approach to proposed water reclamation projects. In the absence of guidelines,
some jurisdictions have used (or are using) demonstration or test sites to explore
water reclamation (CMHC, 1997).

In 2006, the CSA International developed Standard B128.01-06/B128.2-06 (CSA,

2006) to address plumbing requirements for non-potable water systems for
residential or commercial toilet and urinal flushing. In 2007, the WGHRW (2007)
published a second, draft consultative document to address the lack of standards for
plumbing requirements for non-potable water systems and to contribute to the
development of a consistent, national approach for the safe and sustainable use of
household reclaimed water. This document (similar to the EPHC et al. (2006)
guidelines for Australia) adopted a risk-based approach in order to ensure
appropriate quality and management of reused water that is protective of public
health over the long-term. The WGHRW document recommends possible elements
of a management framework that are applicable to on-site or decentralized treatment
of household water for reuse in residential or commercial toilet and urinal flushing. If
the recommended management framework including the treatment technologies are
adopted, the WGHRW document estimates that the following reclaimed water
qualities (to be used in toilet and urinal flushing) will be realized (Table 12):

61
Table 12. Canadian guideline for reclaimed water to be used in toilet and urinal
flushing
(WGHRW, 2007)

4.2.7. Kuwait

Irrigation accounts for approximately 60% of Kuwait’s water use, while approximately
37% is withdrawn for domestic use. Irrigation water is primarily supplied from
groundwater (61%) and reclaimed water (34%). While the use of reclaimed water for
landscape irrigation is growing in urban areas, the main reuse application is
agricultural irrigation (4,470 hectares in 1997), representing 25% of the total irrigated
area. Reclaimed water is only allowed for the irrigation of vegetables eaten cooked
(e.g. potatoes and cauliflower), industrial crops, forage crops (alfalfa and barley), and
irrigation of highway landscapes. Table 13 details the effluent quality standards
established by the Kuwait Ministry of Public Works for reclaimed water (USEPA and
USAID, 2004).

62
Table 13. Reclaimed water standards in Kuwait

4.3. Review of regulations and by-laws regarding greywater reuse in South

Africa

4.3.1. National regulations regarding greywater reuse

In South Africa, there are no national regulations specifically addressing greywater

reuse and management (DWAF, 2006a; Ilemobade et al., 2009a; Rodda et al.,
2010). The regulations listed below (i-iv) however have clauses/sections that
specifically address the treatment, disposal or reuse of waste/greywater. In these
regulations, there is no fundamental objection in principle to the use of household
greywater for non-potable uses, e.g. yard irrigation and toilet flushing. In terms of
common law, the Health Act (No. 63 of 1977), and the National Water Act (No. 36 of
1998), normal precautions with regard to nuisances are however required (Murphy,
2006). Nuisances are defined inter alia as fly/mosquito breeding, objectionable
odours, the surface ponding of wastewater, and the entry of polluted water onto a
neighbouring property (Murphy, 2006). In these regulations, Water Services
Institutions are mandated to provide effective approval and monitoring mechanisms
for waste/greywater reuse within their jurisdictions and to provide suitable and safe
environments for the treatment and reuse of greywater.

i. Government Gazette No. 9225, Regulation 991: Requirements for the purification
of wastewater or effluent (EAF, 1984);

63
ii. the revision of the Water Services Act of 1997 relating to greywater and treated
effluent (DWAF, 2001) (see Figure 30). The revision to the Act specifies the
function of Water Service Institutions as far as the disposal and use of greywater
is concerned and the responsibility of users in ensuring appropriate use of the
resource;

Figure 30. An excerpt of the Water Services Act of 1997 relating to greywater
disposal and use

iii. the revision of the National Water Act of 1998, 37(1) (DWAF, 2004a) relating to
the irrigation of any land with waste or water containing waste generated through
any industrial activity or by a water works. The Act makes no specific reference to
greywater, but refers to “disposal of waste or water containing waste”. This may
be considered to apply also to greywater (Rodda et al., 2010). The authorization
permitted in terms of the revision does not require a wastewater irrigator, who is
owner or legal occupier of the irrigated land, or who has legal access to the land,
to apply for a license in terms of the National Water Act provided that the
irrigation complies with the limits and conditions set out in the revised
authorization (Murphy, 2006), users register such use with a responsible
authority, and the general authorisation applies for a maximum of five years

64
 (DWAF, 2004a). For biodegradable industrial wastewater (maximum of 50 m3 per
day) used for irrigation for instance, the applicable authorization is covered under
the requirement (Section 2.7(iii)) that the irrigator is allowed to irrigate provided
that (Murphy, 2006):
 electrical conductivity does not exceed 200 milliSiemens per metre (mS/m);
 pH is not less than 6 or more than 9 pH units;
 Chemical Oxygen Demand does not exceed 5 000 mg/l after removal of
algae;
 Faecal coliform do not exceed 100 000 per 100 ml;
 Sodium Adsorption Ratio (SAR) does not exceed 5;
 the irrigation of wastewater does not impact on a water resource or any other
person's water use, property or land; and is not detrimental to the health and
safety of the public in the vicinity of the activity; and
 the irrigated site is located above the 100 year flood line, or alternatively,
more than 100 metres from the edge of a water resource or a borehole which
is utilised for potable water or stock watering, whichever is further; and on
land that is not, or does not, overlie a major aquifer.

Although greywater is not mentioned among the types of wastewater considered

above, this is probably the closest that existing legislation comes to providing
guidance for quality of greywater intended for irrigation use (Rodda et al., 2010).

iv. The National Water Resources Strategy (DWAF, 2004c). This document simply
refers to the regulations under the Water Services Act of 1997 (Figure 30).

In summary and according to Rodda et al. (2010) “existing legislation does not
specifically exclude use of greywater….. but there are inconsistencies which arise
from the absence of a clear definition of greywater as a subset of domestic
wastewater which differs in character and hazards from blackwater. These need to
be resolved to clarify the legal position of use of greywater …”.

In response to the limited national regulations regarding greywater reuse, some by-
laws have been developed in municipalities were grey reuse is being practiced in

65
one form or another. By-laws refer to regulations promulgated by a municipality and
thus enforceable within the jurisdiction of the municipality.

4.3.2. Municipal regulations regarding greywater reuse

For many municipalities in South Africa, the use of greywater for a variety of
domestic and non-domestic purposes is often addressed in dedicated
sections/clauses of their water supply, sanitation or effluent specific by-laws. In many
of these by-laws, the use of greywater is attended to on a case-by-case basis and
often delegated to a certain municipality executive. The emphasis in the related
sections/clauses of these by-laws is to ensure appropriate use, assign responsibility,
prevent nuisances, reduce pollution to the environment and reduce risks to public
health. Three of such by-laws are briefly discussed below:

a. The City of Cape Town Treated Effluent By-Law (2010)

In July 2010, the City of Cape Town promulgated its Treated Effluent By-Law (CoCT,
2010) (see excerpt in Figure 31). The City of Cape Town remains the only
municipality in South Africa with a by-law specifically addressing treated effluent. The
by-law aims to control and regulate treated effluent in the City of Cape Town, and to
provide for matters connected therewith. Treated effluent is broadly defined as
“wastewater which has been treated” at one of the city’s wastewater treatment
plants. To this end, the by-law does not directly address greywater which differs in
character and hazards from treated effluent. The by-law is however briefly discussed
here as treated effluent may be considered for toilet flushing. The by-law empowers
the Director, Water and Sanitation, to approve, on a case-by-case basis, the diverse
uses (including toilet flushing) to which treated effluent may be employed. In
summary, the by-law sets out the following: (i) use and responsibilities of each party
involved (i.e. the City and consumers) (ii) provisions relating to the supply of treated
effluent, (iii) general treated effluent installation requirements, (iv) water quality, (v)
health and hygiene, (vi) plans approval procedure, (vii) persons permitted to do
installation and other work, and (viii) good use practices. The treated effluent quality
is benchmarked against the DNHPD (1978) guidelines which essentially specifies
tertiary treatment with nil to 1000 E. coli/100 ml of treated effluent for toilet flushing.

66
Figure 31. An excerpt of the City of Cape Town Treated Effluent By-Law (CoCT,
2010)

b. The Durban Metro Water Supply By-laws (2008)

The Durban Metro (2008) Water Supply By-laws states that no person shall use or
permit the use of water obtained from a source other than the (potable) water supply
system, except with the prior consent of the Authorised Officer and in accordance
with such conditions as it may impose for (i) domestic, commercial or industrial
purposes or (ii) filling of swimming pools. The by-law employs the term non-potable
which caters for the diversity of non-conventional water resources including
greywater. Some of the clauses relevant to greywater in this by-law include:
 The supply of non-potable water shall be entirely at the risk of the consumer, both
as to condition and use, who shall be liable for any consequential damage or loss
arising to himself or others caused directly or indirectly there from, including the
consequences of any bona fide fault of the Councillor or malfunction of a
treatment plant;
 If non-potable water supplied by the municipality is used for irrigation purposes,
the consumer shall ensure that it is applied uniformly over the irrigated areas and
in such a way as to prevent ponding;
 The consumer shall, at his own expense, take such steps as may be necessary
to prevent any run-off of surplus non-potable water from irrigated areas;
 On premises on which non-potable water is used, the consumer shall ensure that
every terminal water fitting and every appliance which supplies or uses such
water is clearly marked with a weatherproof notice indicating the water there from
is unsuitable for domestic purposes.

c. The Moses Kotane Local Municipality Water and Sanitation By-laws (2008)
The Moses Kotane Local Municipality Water and Sanitation By-Laws (2008) Section
78 (1) understands greywater to be wastewater excluding “water derived from any

67
kitchen, excluding clothes washing machines, or from toilet discharges” and as such,
states the following as regards greywater use:
 Section 60. All commercial vehicle washing facilities shall be constructed and
operated in such a manner that 50% of the water used by such facility is recycled
for reuse in the facility;
 Section 61. Any device which entails the recycling or reuse of water shall not
make use of water derived from any kitchen, excluding clothes washing
machines, or from toilet discharges;
 Section 67. (1) No person shall use or permit the use of water obtained from a
source other than the water supply system, except rainwater tanks which are not
connected to the water installation, except with the prior consent of Municipality
and in accordance with such conditions as it may impose, for domestic,
commercial or industrial purposes.
(2) Any person desiring the consent referred to in subsection 67(1)
shall provide the Municipality with satisfactory evidence to the effect that the
water referred to in that subsection complies, whether as a result of treatment or
otherwise, with the requirements of SABS Specification 241-1984: Water for
Domestic Supplies, published in the Government Gazette under General Notice
2828 dated 20 December 1985, or that the use of such water does not or will not
constitute a danger to health.

4.4. Review of guidelines regarding greywater reuse in South Africa

Guidelines represent a compilation of best practice. There are no national guidelines

specifically addressing greywater reuse in South Africa except the brief mention of
greywater reuse for various uses (e.g. irrigation and toilet flushing) in the Guidelines
for Compulsory National Standards and Norms and Standards for Water Services
Tariffs (DWAF, 2002) (briefly discussed below). On the other hand, several
greywater reuse guidelines (or clauses in guidelines) have been developed by
municipalities, groups, and individuals (e.g. Wood et al., 2001; Murphy, 2006,
Carden et al., 2007 and Rodda et al., 2010) involved in greywater reuse of one form
or another. Many of these guidelines have emerged from Water Research
Commission funded studies on greywater management and use, and provide

68
guidance for minimising the adverse impact of greywater on human users and the
environment, and for the planning and operation of greywater facilities (especially
irrigation). Brief discussions on some of these guidelines are presented below:

4.4.1. Guidelines for compulsory national standards and norms and standards for
water services tariffs (DWAF, 2002).

This document provides a framework within which local government can provide
efficient, affordable, economical and sustainable access to water supply and
sanitation. These regulations support the principles enshrined in the Constitution
and the Water Services Act (1997) and help to give substance to the right of access
to a basic level of service. Although, the regulations go a long way towards assisting
municipalities provide basic services in a sustainable manner, they respect the
executive authority of local government. Thus, the regulations provide a broad
framework, by emphasising the principles of sound management, but the discretion
on how this is implemented rests with local government. The guidelines advocate for
the appropriate and safe use of greywater (which is defined as “wastewater resulting
from the use of water for domestic purposes, but does not include human excreta”)
for end-uses such as toilet flushing, urinal flushing and irrigation. The relevant Water
Services Institution must however oversee and control the different phases of the
project in order to protect the health of the public or to prevent any pollution to the
environment.

4.4.2. The City of Cape Town Greywater Guidelines (CoCT, 2005)

The City of Cape Town (CoCT, 2005) developed greywater guidelines primarily to
guide how and where to dispose of greywater so as to avoid pollution in the City’s
informal settlements which benefit from municipal water supply. In this guideline,
greywater is referred to as “wastewater from the washing of laundry, personal
bathing and cooking activities”. Three disposal points, in order of preference, were
recommended, i.e. sewer (preferred), soil (via a soakaway facility) and
stormwater/surface drainage system (this option is only to be considered when the
first two options are impossible). Innovative methods of greywater disposal, e.g. the

69
Tower Garden concept were also recommended. In addition to the above, the
guidelines recommend the following: (i) greywater intakes must be located close to
where the greywater is generated. The maximum distance from a dwelling to the
intake should be 25 m; (ii) where communal washing facilities are provided, sediment
and fat traps are required before the intake (except the intake empties directly into
the sewer); (iii) small sediment and fat traps should be located close (< 3 m) to
greywater intakes and no more than 5 intakes should be served by one sediment
and fat trap; and (iv) once sediments and fat have been removed, conveyance to the
sewer/soakaway/stormwater system can be done using small bore gravity pipelines,
where slopes permit. However, in certain extreme situations where it will be
necessary to pump, very careful consideration must be given to the design,
operation, maintenance, and associated costs of the pump station.

4.4.3. The Durban Metro (1997) guidelines/policy regarding the reuse of treated
sewage effluent

The Durban (currently eThekwini) Metro (1997) developed a guideline/policy

document for the reuse of treated sewage effluent from its sewage treatment works
for industrial and irrigation purposes. Although the document only discusses the
reuse of treated sewage effluent and not greywater, the experiences garnered from
this reuse may have an impact on greywater reuse initiatives within the Metro. This
document discusses, in broad terms, the factors which affect decisions to re-use
treated effluent instead of discharging it into a river, watercourse or out to sea. In
broad terms, the document highlights potential/actual treated effluent reuse in
various sectors of the Metro, i.e. industry (the potential industrial re-use of about 8
million litres of treated effluent from the Southern Wastewater Treatment Works),
irrigation of agricultural land using treated effluent from 2 of the Metro’s sewage
treatment works, and aquaculture (re-use for aquaculture had been attempted twice
in Durban and on both occasions the concessions had to be terminated because
they were economically unviable). For economical and other reasons, treated
effluent reuse was not considered for potable water production, recharge of ground
water and domestic use (including toilet flushing).

70
4.4.4. Greywater management in dense informal settlements (Wood et al., 2001)

Wood et al. (2001) highlighted the potential for greywater generation to be

considered and provided for when planning and developing settlements. They
concluded that integration of suitable long-term service provision was essential to
alleviating the problems of greywater management which they observed in their
study of dense informal settlements of South Africa. Some of the guidelines which
were proposed regarding the planning and management of greywater and greywater
systems for dense informal settlements are listed below (Rodda et al., 2010):
 Settlements should not be established on steep slopes because of the increased
risk of erosion;
 No development should occur in the 1:50 year floodline, and natural drainage
channels should be maintained;
 Where water points are located near rock outcrops or where the soil in the area is
unsuitable, it may be possible to use surface drains to transport greywater to a
more suitable area for disposal;
 Provision must be made for the collection of greywater and leakage from water
standpipes. Preferably, infiltration beds and soakaways should be provided at the
standpipes (or drainage) to gravitate the greywater to an appropriate site for
handling and disposal so that ponding of contaminated water is minimised.
Standpipes should be no further than 100 m from each household;
 The preferred option for greywater disposal is by gravity to sewer – the collection
and treatment of greywater in ponds or wetlands is not a viable option for many
high-density settlements owing to the lack of large open spaces, health risks, and
safety considerations.

4.4.5. Reporting on the status quo of greywater in informal areas in the Western
Cape and guidelines for its management (DWAF, 2005a)

In April 2005, a status quo report was published by DWAF (currently Department of
Water Affairs and the Environment, DWAE) on the management of greywater in
informal areas of the Western Cape. The report recommends that any discussions
on a future national greywater management strategy must include input from Water

71
Services, as the implementation of the strategy is likely to have financial implications
for Water Service Institutions especially if there are design implications in terms of
new reticulation systems. Furthermore, the Directorate responsible for the
development of the policy must be clearly defined as it affects Water Resource
Management, Water Supply and Sanitation.

4.4.6. A scoping study to evaluate the fitness-for-use of greywater in urban and peri-
urban agriculture (Murphy, 2006)

Murphy’s (2006) study was focused on the use of greywater for irrigation. Murphy
(2006) provided a list of steps to be taken when planning greywater use for irrigating
garden crops. Several of these steps (listed below) (Rodda et al., 2010) may also be
broadly applied to other greywater end uses:
 Greywater availability – the available sources of greywater (e.g. laundry, bath,
wash basin, and shower) should be identified. For each source, the volume of
greywater produced on a daily or weekly basis should be estimated;
 Identification of preferred greywater sources – greywater from different sources
should be used in the following order of preference:
a) bathroom greywater;
b) laundry greywater (preferably use only rinse-wash water);
c) kitchen greywater (rinse water only, unless when the greywater is to be used
for composting).
 Example of a treatment option – using a sieve at the greywater source for
trapping hair, lint and food particles;
 Regulations – applicable regulations (e.g. municipal by-laws) would need to be
determined for each case;
 Health risks associated with greywater use – greywater should not be used if any
member of the household has an infectious disease;

In addition to the planning steps listed above, Murphy (2006) also provided extensive
practical recommendations for day-to-day management of greywater irrigation. Some
of these, which may also be broadly applied to other greywater end-uses are
summarized as follows:

72
 For newly-designed houses, greywater outlet pipes should be kept separate until
outside the house;
 For piped greywater irrigation systems, a minimum of a simple filter (e.g. a nylon
stocking) should be used. It should be possible for greywater irrigation piping to
be completely and easily drained. Greywater storage tanks should be covered;
 For piped greywater systems at dwellings connected to sewage systems, there
should be a diversion facility to the sewage system at or near the greywater
source outlet;
 Greywater should not be allowed to leave the property on which it is generated,
except through the sewer;
 Greywater should not be stored for longer than 24 hours;

4.4.7. Understanding the use and disposal of greywater in the non-sewered areas of
South Africa (Carden et al., 2007)

Carden et al. (2007) surveyed greywater (all domestic wastewater except

blackwater) generation and provision for greywater management in unsewered
settlements across South Africa. They concluded that the density of a particular
settlement, together with the consumption of water per dwelling unit, were the most
critical factors in determining whether greywater could be safely disposed on-site
(including reuse options). However, they observed that it was behavioural patterns
that drove the reality of how greywater was disposed. Although the level of service
with respect to water supply to unsewered areas varied widely, only two categories
seemed to have any influence on the amounts of water consumed in each dwelling,
viz. having a yard tap on the property or having to walk to fetch water, irrespective of
the distance walked (Carden et al., 2007 cited by Rodda et al., 2010).

Carden et al. (2007) developed a relationship to describe the interdependence of

dwelling density and average volume of greywater volume generated by each
dwelling. They termed this interdependence the greywater generation rate, G.
Management guidelines were proposed for different ranges of G:
 Low density greywater generation was defined as < 500 ℓ/ha.day, which generally
equates to dwelling densities of < 10 du/ha and plot sizes of > 800 m2.

73
 Soakaways installed at water collection points and standpipes should be
sufficient to protect water resources and prevent health risks;
 Low/medium density greywater generation was defined as 500-1 500 ℓ/ha.day,
equating to dwelling densities of 10-30 du/ha and plot sizes of 300-800 m2.
Soakaways must be installed at tap stands and in-home or yard connections
should be connected to an on-site disposal system;
 Medium/high density greywater generation was defined as 1 500-2 500 ℓ/ha.day,
equating to densities of 30-50 du/ha and plot sizes of 130-150 m2. If yard
connections are supplied as recommended by DWAF, onsite disposal systems
should be installed; otherwise formal washing areas with disposal options are
required;
 High density greywater generation was defined as > 2 500 ℓ/ha.day, equating to
densities of > 50 du/ha and plot sizes of < 150 m2. There should be off-site
disposal of all effluent.

Greywater management options could then be determined by way of rule-based flow

diagrams which ask relevant questions for each of the criteria identified to determine
options for greywater management and disposal. Limits were given for some of
these criteria where it was deemed possible to provide recommendations for off-site
disposal of greywater. Decision trees which were also presented in the report could
help decision-makers to determine quickly whether on- or off-site disposal of
greywater should be considered (Rodda et al., 2010).

In Carden et al.’s (2007) study, it was observed that people living in non-sewered
settlements were generally not prepared to use greywater for irrigation purposes as it
is considered harmful to certain species of plants. This is due to the multiple uses of
the greywater before it is considered suitable for disposal and the large variation in
the concentration of the various pollutants within. The water quality data from the site
surveys confirmed that greywater from non-sewered areas is generally unfit for use

74
4.4.8. Sustainable use of greywater in small-scale agriculture and gardens in South
Africa (Rodda et al.,2010)

The aim of Rodda et al.’s (2010) report was to develop guidelines for the sustainable
use of greywater in small-scale agriculture and gardens in rural villages, peri-urban
and urban areas of South Africa. Central concepts identified from the literature
review and case studies, and deliberations between relevant stakeholders
determined the underlying principles and the structure of the developed Guidance
Report. The focus of the Guidance Report was defined as (Rodda et al., 2010):
 Minimisation of risks of illness in handlers of greywater and greywater irrigated
produce, or consumers of greywater-irrigated produce;
 Minimisation of risks of reduction in growth or yield of plants/crops irrigated with
greywater;
 Minimisation of risks of environmental degradation, especially reduction in the
ability of soil irrigated with greywater to support plant growth.

The Guidance Report was specifically intended to address irrigation use of greywater
only, and was not targeted at providing a general solution for the disposal of
greywater. However, some of the recommendations may be applied to other
greywater uses.

The structure of the Guidance Report was as follows (Rodda et al., 2010). The core
of the Guidance Report is provided by the section “Guidance for greywater use in
small-scale irrigation in South Africa”:
 What is greywater?
 Why use greywater for irrigation?
 Concerns about the use of greywater for irrigation:
 Health considerations;
 Plant growth and yield;
 Ability of soil to support plant growth;
 Purpose of the Guidance Report:
 Intended users of the Guidance Report;
 Focus of the Guidance Report;

75
  Major sources used;
 Legislative context of greywater use for irrigation;
 Special considerations;
 Guidance for greywater use in small-scale irrigation in South Africa:
 Guide to managing risks and uncertainty:
In this sub-section, 3 categories of greywater use are identified, based on the
extent of characterisation of greywater and, by implication, on compliance with
quality limits. Use restrictions are identified for each category. The most
stringent restrictions apply to greywater used without characterisation.
Minimum analysis – comprising pH, electrical conductivity, sodium adsorption
ratio and E. coli –, and compliance with quality limits on these, are associated
with less stringent restrictions. The least restrictions are associated with use
of greywater undergoing full analysis (minimum analysis plus boron, chemical
oxygen demand, oil and grease, suspended solids, total inorganic nitrogen
and total phosphorus);
 Greywater quality: Guide to greywater constituents:
The quality limits in each category are specified in this sub-section;
 Greywater quality: Mitigation of greywater quality:
This section provides means of adjusting to or improving on greywater quality.
Two approaches are considered: agricultural practices to mitigate the effect of
predominantly chemical constituents such as sodium; and treatment to
improve, predominantly, the organic and microbiological quality of greywater;
 Greywater quantity: Guide to irrigation volumes;
This sub-section guides users in selecting the volume of greywater to be
applied and in adjusting this for site-specific conditions.

Some of the recommendations to emerge from the study which could be generally
employed for other uses of greywater are as follows:
 Implementation: Capacity building at Local Authority level
A short educational pamphlet on greywater and greywater irrigation, aimed
specifically at local authorities, should be developed and distributed;
 Implementation: Education of greywater users

76
  Potential greywater users need to be involved in planned greywater
implementations from the planning stages, informing them of the benefits and
risks of greywater use for irrigation, allowing them to express their views and
concerns, and providing a mechanism for them to be involved in decision
making.
 Potential irrigation users of greywater need information to practice greywater
irrigation in a safe and sustainable manner. Although this information is
provided in the Guidance Report, it would be helpful to provide users with
quick reference sheets to support the more comprehensive document. This
could take the use of one-page information sheets.
 Once greywater implementation has been planned and initiated, greywater
users need ongoing monitoring and support. This should be tailored to meet
the different information and support needs of low income rural and peri-urban
settlements and middle to higher income urban settlements.
 Legislation: Recognition of greywater and beneficial greywater use in water and
waste legislation
Current legislation pertaining to disposal and use of water and waste falls short in
that a definition of greywater as a separate wastewater stream is lacking. Clarity
is needed for the future by explicit definition of greywater and the beneficial uses
to which it may be put.

4.5. Government pronouncements regarding greywater reuse in South Africa

Table 14 presents references to publications or pronouncements of the national

government through the Department of Water Affairs and the Environment, DWAE
(formerly DWAF) as regards greywater reuse for different end uses. Of particular
note is the fact that DWAE, in various places and through various offices, has
proactively encouraged greywater reuse for particularly toilet flushing and garden
irrigation.

77
Table 14. Reference to publications/pronouncements by DWAE regarding
greywater reuse in South Africa
Reference Guideline/Suggestion/Comment
DWAF (2008). National Water Week “Tips to save and manage water:
2008.  Use greywater – used water from baths, washing
http://www.dwa.gov.za/events/waterw machines and other safe sources – to flush your toilet”
eek/2008/Tips.aspx  Use greywater ……. to water your garden.”

DWAF (2007). National Water Week “Use greywater….to water your garden”
2007.
http://www.dwaf.gov.za/events/Water
Week/2007/facts.asp
DWAF (2006b). Handing over Speech by Mrs Lindiwe Hendricks, Minister of Water Affairs
ceremony of the Baswa Le Meetse and Forestry at Mammutla Primary School, Mammutla
Awards prizes. 22 September 2006. Village, Taung, North West. “I was impressed with the
http://www.dwaf.gov.za/Communicatio project of our national team, which comprised three young
ns/MinisterSpeeches/2006/BaswaLeM girls from a school in rural KwaZulu-Natal. They used their
eetse22Sep06.pdf knowledge of water and science to find useful ways of
turning the household wastewater (greywater) into
productive water that could be used to effectively grow plants
and vegetables.”
DWAF (2005b). National Water Week “Minister Sonjica urges water saving at homes through the
2005. use of greywater to water your garden and flush your toilets”
http://www.dwaf.gov.za/events/Water
Week/2005/Documents/WaterWheelJ
an05d.pdf
DWAF and NORAD (2004b). This document provides simple guidelines on the
Introductory Guide to appropriate implementation of greywater reuse systems.
solutions for water and sanitation.
TOOLKIT for WATER SERVICES:
Number 7.2. Produced under The
NORAD-Assisted Programme for the
sustainable development of
groundwater sources under the
Community Water and Sanitation
Programme in South Africa. March.
http://www.dwa.gov.za/Groundwater/
NORADToolkit/7.2%20Introductory%2
0Guide%20to%20Appropriate%20Sol
utions%20for%20Water%20and%20S
anitation.pdf

4.6. Pertinent issues from the review of regulations, by-laws and guidelines for
greywater reuse in South Africa

From the review of regulations and guidelines conducted above and the overview of
government’s broad position regarding greywater reuse for various uses, some key
issues worth noting are listed below:
i. In South Africa, there are no national regulations specifically addressing
greywater reuse and management. There are however some sections/clauses in

78
 broad regulations and by-laws which address greywater reuse and/or
management, albeit to differing degrees of detail, most of which are very limited;
ii. In the regulatory sections/clauses of broad regulations and by-laws reviewed,
there is no fundamental objection in principle to the use of household greywater
for non-potable uses, e.g. garden irrigation and toilet flushing, as long as
nuisances which compromise public health and the pollution status of the
environmental are avoided. In fact, in the publications and pronouncements listed
in Table 14, there is broad encouragement for greywater reuse for toilet flushing
and garden irrigation.
iii. Current national regulations that mention/discuss the use and disposal of

greywater fall short in that a definition of greywater as a separate wastewater

stream and distinct from blackwater is lacking. The implication of this is that the
understanding (and thus, legal position) of greywater is inconsistent amongst
various stakeholders. For example, the City of Cape Town guidelines (CoCT,
2005) define greywater as “wastewater from the washing of laundry, personal
bathing and cooking activities”, the Moses Kotane Local Municipality Water and
Sanitation By-law understands greywater to be domestic wastewater excluding
“water derived from any kitchen …. or from toilet discharges”, and the guidelines
for compulsory national standards and norms and standards for water services
tariffs (DWAF, 2002) defines greywater as “wastewater resulting from the use of
water for domestic purposes, but does not include human excreta”;
iv. There are no national guidelines specifically addressing greywater reuse in South

Africa. A nationally consistent approach to the management of health and

environmental risks from greywater reuse requires high-level national guidance
on risk assessment and management. These guidelines will not be mandatory
and will have no formal legal status. However, their adoption will provide a shared
national objective, and at the same time allow flexibility of response to different
circumstances at regional and local levels (EPHC et al., 2006);
v. Several WRC funded projects (e.g. Wood et al., 2001; Murphy, 2006; Carden et
al., 2007; and Rodda et al., 2010) have developed guidelines for greywater use
and management in especially dense, non-sewered and/or informal areas of
South Africa and for diverse irrigation purposes. These guidelines need to be
compiled into a comprehensive document which addresses greywater use and

79
 management and may be expanded to include guidelines addressing other
possible end-uses of greywater such as toilet flushing);
vi. The DWAF (2005a) report recommends that any discussions on a future national

greywater management strategy must include input from Water Services, as the
implementation of the strategy is likely to have financial implications for Water
Service Institutions especially if there are design implications in terms of new
reticulation systems. Furthermore, the Directorate responsible for the
development of the policy must be clearly defined as it affects Water Resource
Management, water supply and sanitation;

80
 5. GREYWATER TREATMENT TECHNOLOGIES AND FRAMEWORK FOR
EVALUATING LOCALLY AVAILABLE GREYWATER TREATMENT UNITS

The trend of decentralised living and environmental consciousness together with

increasing water scarcity has created a market for small wastewater treatment units
in South Africa and many other locations around the world. For reasons of cost,
convenience and installation, many small wastewater treatment units are
manufactured as ‘package plants’. Judd et al., (2006) defines a package plant as a
complete unit fabricated in a factory and shipped to location for installation. This is in
contrast to a conventional wastewater treatment plant that is installed on site.
Package plants may be designed to treat flows as low as 7.57 m3/day or as high as
1892.5 m3/day. Package plants are used by a variety of users including holiday
resorts, private housing estates, hotels, factories, and individual households. As a
result of this, most locally available package plants range in capacity from 4 PE to
1000 PE or more. PE represents ‘Population Equivalent’ = ±120l/day.

Treatment is necessary to reduce the amount of solids, organic matter, nutrients and
pathogenic organisms in greywater. Currently, there have been tremendous
successes recorded in terms of wastewater treatment technology. However, despite
the successes of treating wastewater at a large scale, treatment is less reliable as
volume of influent decreases. This is because:
 Smaller plants are subjected to a wider range of hydraulic loads than their larger
counterparts (Gaydon et al., 2006);
 The smaller the unit is, the more difficult it becomes to operate. This is due to
limitations in the size of pumps, fittings, and pipes. Furthermore, the relative size
of debris increases as the size of the unit decreases, making blockages more
likely and the requirement for maintenance more frequent;
 Smaller plants, as a result of being packaged, are often left unattended for longer
periods of time (e.g. 3-12 months at a time). Break downs therefore occur
regularly as a result of neglected preventative maintenance.

With the growth of on-site grey/wastewater reuse, the selection of appropriate

package plants has become needful and a challenge. This challenge is more so in
the case of novel, emerging or imported package plants where little information and
81
experience under local conditions are known.

This chapter of the report reviews greywater treatment technologies commonly used,
presents a database of locally available greywater package plants as at 2009 and
develops a framework for the evaluation of locally available, small greywater
treatment plants, with the treated effluent specifically for toilet flushing.

Two projects commissioned by the WRC have attempted to provide some guidance
on the evaluation of small water and wastewater treatment plants, i.e. Guidebook for
the selection of small water treatment systems for potable water supply to small
communities (Chris Swartz et al., 2007) and Evaluation of sewage treatment
package plants for rural, peri-urban and community use (Gaydon et al., 2006). This
chapter builds on some of the work presented by these reports within the context of
greywater reuse for toilet flushing.

5.1. Review of greywater treatment technologies

In Li et al. (2009), greywater treatment for unrestricted, non-drinking urban reuses

(including toilet flushing) typically requires four processes – pre-treatment; physical,
chemical, biological treatment; filtration; and disinfection (if restricted reuse,
disinfection may be excluded). Individually, these processes cannot guarantee
adequate treatment (see Table 15) and hence, many systems incorporate a
combination of these processes. Figure 10 shows Li et al.’s (2009) proposed
treatment flow for different qualities of greywater for urban non-drinking purposes.
Discussion on physical, biological and chemical treatment processes are discussed
below.

82
Table 15. Overview of treatment technologies and their pollutant removal
abilities
(Landcom’s WSUD strategy, 2003)
Category Sub- Treatment efficiency
category

ble organics
solids (TSS)

phosphorus
Biodegrada
Suspended

Pathogens
Nutrients:

Nutrients:
removal)

nitrogen
(BOD

Salts
Biological Membrane Yes Yes Function Function No Function
(suspended bioreactor of size of size of size
and fixed Recirculating Yes Yes Yes Limited No Limited
growth) media filter
Chemical Disinfection No No No No No Yes
Physical Sand filtration Yes Function of Limited Limited No Limited
size
Membrane Yes Function of Function Function Reverse Function
filtration size of size of size osmosis of size
only
Natural Subsurface Yes Yes Yes Yes No Good
flow wetland

Figure 10. Greywater treatment for non-drinking urban reuses (Li et al., 2009).

83
5.1.1. Biological treatment technologies

Biological treatment promotes natural processes to break down high nutrient and
organic loading waters. Biological treatment alone is not usually sufficient to produce
an effluent suitable for reuse. In all cases therefore, the biological reaction must be
accompanied by a physical process to retain active biomass and prevent the
passage of solids into the effluent (Jefferson et al., 2001).

Common amongst most locally available package plants, is the actual treatment of
greywater using biological processes, i.e. suspended growth or fixed film/growth
systems (presented below) (Laas and Botha, 2004 and Gaydon et al., 2006).

Suspended Growth Systems (Münch, 2005)

The activated sludge process is the best-known suspended growth system. This
process is most commonly used in large, centralised and small wastewater treatment
plants. Activate sludge is the process whereby sewage is aerated (using
atmospheric air or pure oxygen) and agitated in order to promote the growth of
beneficial microorganisms that break down organic matter and produce biological
flocculent. The process usually occurs in two distinct phases (and therefore vessels),
i.e. aeration followed by settling. Four processes are common in all activated sludge
systems:
i. A flocculent, aerated slurry of microorganisms (which is called “mixed liquor
suspended solids” or MLSS) is utilised in a bioreactor to remove soluble and
particulate organic matter from the wastewater;
ii. Quiescent settling is used to remove the MLSS from the process stream,
producing an effluent that is low in organic matter and suspended solids;
iii. Settled solids are recycled as a concentrated slurry from the clarifier back to the

bioreactor;
iv. Excess MLSS (sludge or biosolids) is discharged from the bioreactor to control

the solids retention time to a desired value.

There are several process variations to the activated sludge process- the main ones
are briefly described below:

84
a. Sequencing Batch Reactor (SBR)
The SBR process is a fill-and-draw-type reactor that acts as aeration basin and final
clarifier. Wastewater and biomass are mixed and allowed to react over several hours
in the presence of air. At a certain point in time, the aeration is turned off and the
mixed liquor in the reactor is allowed to settle, thereby removing the need for a
separate settling tank.

After a short settling period, the clarified treated effluent is discharged via a specially
designed decanter. One design variant is that the decanter follows the liquid level
down enabling only the clear, treated effluent to be discharged, while the biomass
continues to settle. Once the treated effluent is discharged the reactor is available to
treat a further batch of wastewater. This way, the process operates on a batch
treatment principle, with the operations being sequenced. Two or more SBRs are
usually operated in parallel unless a sewage storage tank is used.

b. Membrane Bioreactor (MBR)

A membrane bioreactor (MBR) combines the process of a suspended growth reactor
(system) and membrane filtration into a single unit process. MBRs replace the need
for a separate filtration process with a treatment process that has a small footprint
and produces high quality effluent with low TSS, BOD, and turbidity that meets
almost all health criteria guidelines. There are two basic configurations for a MBR: a
submerged integrated bioreactor that immerses the membrane within the suspended
growth reactor (Figure 11) and a bioreactor with an external membrane unit. MBRs
are usually of a modular design such that it may be located indoors or outdoors and
it may be for large or small scale applications. The suitability of MBRs for greywater
reuse is strongly influenced by its capability to remove both biological contaminants
without the use of chemicals for treatment. MBRs provide a proven and reliable
treatment technology, having been used extensively in Japan for greywater and
blackwater reuse systems.

Control of membrane fouling is an important operational issue. If fouling is not

controlled, membranes will wear quicker, and there will be increased energy costs
and decreased effluent quality. MBRs have higher capital (which includes expensive
membranes) and energy (chemicals required for membrane cleaning) costs than
85
other treatment systems. It may be susceptible to shock loading of organic matter
and bactericidal chemicals.

Figure 11. An immersed membrane bioreactor (Jefferson et al., 2001)

Fixed Film/Growth Systems (Münch, 2005)

Fixed film/growth systems are systems where the microorganisms are attached to a
surface that is exposed to the water. Many locally available package plants employ a
purely fixed film system or a combination of fixed film and suspended growth
systems.

a. Rotating Biological Contractor (RBC)

The Rotating Biological Contactor (RBC) supports a biologically active film, or
biomass, of aerobic micro-organisms. An RBC treatment system (Figure 12) typically
comprises of three units:
 Primary Zone: A settlement tank where wastewater enters and solids settle and
are stored for subsequent removal. Anaerobic digestion may take place within the
tank.
 RBC: This is where the biological treatment takes place. Numerous discs
attached to a shaft form the RBC assembly, which is partially submerged in a
trough to create an environment for an active biomass to develop on the media.
The RBC is slowly rotated to bring the biomass into alternate contact with the
wastewater and atmospheric oxygen.
 Final Clarification Zone: Here settlement of the mixed liquor and excess biomass
takes place.

86
Figure 12. A rotating biological contactor (Jefferson et al., 2001)

b. Submerged Aerated Filter (SAF)

The SAF process can be described as follows: Settled wastewater is fed from a
primary tank into the first stage of a reactor at a controlled rate, where it is mixed
with the aerated bulk liquid already present. Air is introduced into the reactor through
a fine bubble diffuser system at the base of each chamber. A uniquely structured
media is suspended over the fine bubble membrane diffuser to provide optimized
contact between the oxygen-rich wastewater and the biomass.

With a high surface area to volume ratio, the media supports a biologically active film
of micro-organisms, to treat the wastewater by using oxygen from the air provided.
Manufactured from lightweight vacuum-formed PVC sheets (for example), bonded
together to form packs, the media can easily be removed for maintenance.

When the oxygen-rich wastewater comes into contact with the biomass attached to
the surface of the media, organic pollutants are broken down by the biomass. The
flow of air can be controlled to optimize the levels of dissolved oxygen within the
reactor, ensuring that the process is energy efficient.

Recirculating media filters (Landcom’s WSUD strategy, 2003)

Recirculating textile filters (RTF) and recirculating sand filters (RSF) are biological
treatment processes removing organic material from the wastewater. Recirculating
textile filters are similar to trickling filters. However, the media used for the growth of
the biofilms are textiles rather than plastics or rocks. RTFs are available in small
compact package plants and therefore, suitable for decentralised treatment. The
RTF and RSF consist of two major components. The first is the biological chamber
and low-pressure distribution system. The wastewater flows between and through
87
the non-woven lightweight textile material in the RTF and through a bed of sand in
the RSF. The second major component is a recirculating tank and pump. The pump
typically returns 80% of the filtrate back to the chamber. The pump fills the chamber
every 20 to 30 minutes. The remaining effluent may be diverted to a storage tank or
discharged.

5.1.2. Chemical treatment technologies

Chemical treatment involves chemicals, typically coagulants and disinfectants, which

are used to increase the removal rate of pollutants or destroy pathogenic organisms
but does not remove solids. Disinfection destroys pathogenic microorganisms in
water to ensure public health. Eradication of waterborne pathogens is the most
important public health concern for water treatment. Disinfection ranges from boiling
water to large-scale chemical treatment for water supplies. The three most common
disinfection methods are ultra-violet radiation, chlorination and ozonation.

Ultraviolet (UV) radiation

Uses UV light to deactivate microorganisms in water. The short UV wavelength
irradiates microorganisms. When the UV radiation penetrates the cell of an
organism, it destroys the cell’s genetic material and its ability to reproduce. UV
disinfection has low capital and operating costs, is easy to install and operate and is
well suited to small-scale water treatment processes. UV is ineffective in turbid or
milky waters as the microorganisms hide behind suspended particles to evade
irradiation.

Chlorination
Chlorine, a strong oxidant, is the most common water disinfectant. Chlorine can be
added in gaseous form (Cl2), hypochlorous acid or as hypochlorous salt – typically

Ca(OCl)2. Chlorine addition requires chemical handling and storage. Some by-

products of chlorination are carcinogenic. Chlorine provides residual microbial

control, i.e. it continues to disinfect water after the water has passed through the
chlorination point and hence, it is typically selected for drinking water supply
systems. Optimal chlorination dosage is dependent on the concentration, water pH

88
and temperature. The pH exerts a strong influence on the chlorination performance
and is therefore regulated.

Ozonation
Ozone is a more powerful oxidising agent than the above disinfectants. Ozone is
created by an electrical discharge in a gas containing oxygen, i.e. 3O2→2O3. Ozone
production depends on oxygen concentration and impurities such as dust and water
vapour in the gas. The breakdown of ozone to oxygen is rapid. It is impossible to
maintain free ozone residuals in water for any significant time.

Three of the schemes using predominantly chemical technology for greywater

recycling were reported in Parsons et al., 2000; and Lin et al., 2005. Two of the three
schemes were based on coagulation with aluminium. The first scheme used a
combination of coagulation, sand filters and granular activated carbon (GAC) for the
treatment of laundry greywater. This scheme was effective, with residuals of 10 mg/l
for BOD and below 5 mg/l for suspended solids. The coagulation stage alone
achieved 51% of BOD removal and 100% of suspended solids removal. The second
scheme combined electro-coagulation with disinfection for the treatment of low-
strength greywater with BOD residuals of 9 mg/l, a turbidity residual of 4 NTU and
undetectable levels of E. coli. However, the greywater source had very low organic
strength with BOD concentrations of about 23 mg/l. These two schemes achieved
the above results in relative short times (20 and 40 minutes respectively). The third
scheme was based on photocatalytic oxidation with titanium dioxide and UV
disinfection. This scheme achieved good results. Within 30 minutes, this method was
reported to achieve a 90% removal of organics and removal of total Coliform of 106
cfu/100 ml (Parsons et al., 2000).

Advantages of chemical treatment include: the treatment can be located indoors, it

has a small ecological footprint, it separates turbidity and organic matter from the
effluent, and it efficiently disinfects and thus, this technology is potentially suitable for
small scale applications. Disadvantages include that the technology does not remove
solids and it often requires a high capital cost.

89
5.1.3. Physical treatment technologies
(Landcom’s WSUD strategy, 2003)

Physical treatment technologies rely on physical separation of the effluent from the
pollutant such as filtration, sedimentation and flotation. Physical processes, which
achieve a reasonable decrease in organic pollutant load and turbidity of greywater,
include:

Sand filtration
Sand filters have been used for water treatment for more than 100 years. Filtration is
a tertiary treatment process that typically occurs after secondary (biological or
chemical) treatment as it removes residual suspended solids and organic matter
prior to disinfection. Sand filters are usually lined excavated structures filled with
uniform media over an underdrain system. The wastewater is poured on top of the
media and percolates through to the underdrain system. Design variations include
recirculating sand filters where the water is collected and recirculated through the
filter. For effective microbial control, low flow is desired through the sand filter. This
ensures contact between the sand media’s biofilm (which forms on the upper layer of
the sand filter) and water. The biofilm helps to adsorb colloidal pollutants and
encourages oxidation of the organic material as oxygen diffuses within the biofilm.
Depth filtration is a variation of the sand filter. Depth filtration uses a granular media,
typically sand or a diatomaceous earth, to filter effluent. Typically there are four
layers of filter media. The particle size decreases through the filter’s layers. The
coarser top layer removes larger particles and finer material is removed towards the
lower layers, increasing the efficiency of the filter in comparison to the conventional
sand filters.

Membrane filtration
Membrane (or cross flow membrane) filtration is a physical separation process to
filter pollutants (particles, bacteria, other microorganisms, natural organic matter and
salt) using a semi-permeable media. There are 4 broad classes of membrane
filtration namely (i) micro-filtration, (ii) ultra-filtration, (iii) nano-filtration and (iv)
reverse osmosis. Micro-filtration has the largest pore size, decreasing to

90
ultrafiltration, nanofiltration and reverse osmosis. The treated water is thus generally
very low in turbidity and below the limit of detection for coliforms. The key technical
limitation of membrane filtration systems is that of fouling of the membrane surface
by pollutants. This increases the hydraulic resistance of the membrane,
commensurately increasing the energy required for membrane permeation and/or
decreasing the permeate flux. The pressure requirements, pore size and typical
pollutant removal are summarised in Table 16. Fouling can be suppressed by
operating at a lower membrane flux or can be substantially removed by cleaning –
the former requiring larger membrane areas to process the same volume of
greywater (Jefferson et al., 2001). Advantages include that the technology can be
located indoors, it is suitable for large and small applications, the quality of treated
effluent is generally very high, and it is not susceptible to chemical shocks. A major
disadvantage is the high capital cost of membranes.

Table 16. Key features of membrane filtration

(Landcom’s WSUD strategy, 2003)

5.1.4. Natural treatment technologies

Natural treatment systems include artificial or constructed wetlands (reed beds,

lagoons or ponds) which are a complex collection of water, soils, microbes, plants,
organic debris, and invertebrates. Greywater is commonly treated by natural systems
in areas without a public sewer system. Fittschen and Niemczynowicsz (1997)
reported a 100 PE greywater treatment scheme in Sweden, which included a
sedimentation tank, a reed bed and sand filter followed by an artificial pond.
Phragmites communis were planted on an area of about 600 m2 with depth of 0.6 m
91
to allow a residence time of 4 days.

Subsurface wetlands are a proven technology to remove organic matter and

suspended solids from wastewater. In subsurface flow wetlands, wastewater is
treated in horizontal or vertical (Figure 13) flow reed beds where the water is below
the surface of a gravel bed to minimise undesired insect breeding and odour
formation. The soil typically has a high permeability and contains gravel and coarse
sand. Some flora/plants, which are utilized in these wetlands, have bactericidal
properties and are able to treat some chemical pollutants. Common plants used
include phragmites, Bauma, water hyacinth (Eichhornia crassipes), Typha and
schoenoplectus.

Subsurface wetlands are typically applied in wastewater treatment systems where

there is a relatively consistent influent flow rate. In comparison, surface wetlands
used to treat stormwater flows must be able to cope with variations in flows as a
result of rainfall patterns. Subsurface flow wetlands provide a low cost, very low
energy, natural treatment system. As the flow percolates through the wetland,
biological oxygen demand (BOD) and total suspended solids (TSS) are
predominately reduced by biological decomposition.

Waste treatment levels, seasonal temperature variation and flora characteristics

determine the size of the pond and infiltration areas. Infiltration areas vary in size
from 0.7 m2 (Green and Upton, 1995) to 8 m2 (Bucksteeg, 1990) per person served
by the facility and depend on the wastewater characteristics and the targeted effluent
quality. Odour formation can result from poor oxygenation, rather than organic
overload, which then has an impact on ammonia concentration. Odour problems can
generally be ameliorated through improved aeration, light and temperature.

Advantages include inexpensive, energy-efficient, and chemicals not required for

treatment while disadvantages include must be located outdoors, may require very
regular maintenance, has a large ecological footprint, and is climate-dependent.

92
Figure 13. Cross-section of a reed bed (Bart Senekal Inc, 2003)

5.2. Database of locally available greywater units for toilet flushing

A list of locally available greywater treatment unit manufacturers / suppliers whose

units have been advertised as capable of treating grey/waste water for toilet flushing
is presented in Appendix B1. Initial information on these plants was obtained from
several sources including the following:
 Guidebook for the selection of small water treatment systems for potable water
supply to small communities. WRC report no TT 319/07. (Chris Swartz et al.,
2007);
 Evaluation of sewage treatment package plants for rural, peri-urban and
community use. WRC report no. 1539/1/06. (Gaydon et al., 2006).
 The Global Directory for Environmental Technology (The Green Pages, 2009).

Detailed information on each of the package plants was obtained by directly

requesting specific information from individual manufacturers/suppliers using certain
performance criteria (discussed in the next session). Manufacturers/suppliers were
typically contacted as follows:
1. A letter was drafted explaining the project and requesting plant specific
information using a questionnaire (Appendix B2);
2. The letter and questionnaire were then faxed or emailed to the relevant contact
personnel and telephone calls were made to confirm receipt and request
responses. Thirty manufacturers were originally compiled, 25 were sent the letter
and questionnaire and 10 responded.

93
5.3. Development of the framework for the evaluation of greywater units
5.3.1. Performance criteria for evaluating treatment units

The performance criteria used in the framework for the evaluation of the 10 package
plants in order to select the most appropriate for the pilot sites were obtained from
the following standard/guideline documents:
1. The revision of the National Water Act of 1998, 37(1) (DWAF, 2004a);
2. Murphy (2006);
3. The Official Journal of the European Union (2005);
4. Landcom’s WSUD strategy (2003);
5. The USEPA Code of Practice for Wastewater Treatment Systems for Single
Houses (PE < 10) (USEPA, 2007);
6. National and international wastewater quality guidelines in Surendran & Wheatley
(1998)

5.3.2. The framework, weights, scores and scoring range

The framework for evaluating package plants for greywater/wastewater recycling for
toilet flushing using the 3 key issues are shown in Tables 18, 19 and 20. Specific
references for the evaluation of each criterion are included on the framework. The
framework was developed using the Triple Bottom Line, TBL approach which
provides a robust structure for evaluating alternatives. It is designed to provide
decision-makers with a framework to understand the costs, benefits, impacts, etc. of
alternatives across a spectrum of social, economic and environmental attributes. In
this way, a more balanced view of alternatives is created rather than one that relies
on only quantifiable factors. It also allows decision makers to vary or weigh criteria to
discover those criteria that have the greatest influence on differentiating alternatives
(CRD, 2007).

The TBL approach typically involves the following (Ilemobade et al., 2009b): (i) goals
to be achieved; (ii) criteria which determine whether the goals are achieved; (iii)
evaluation questions/statement by which each criteria is measured, (iv) a range of
scores for measuring each criterion; and (v) weights for each criterion.

94
The weights employed in the framework are based on the average weights obtained
by Ilemobade et al. (2009a) based on decision-makers’ ranking of key issues to be
considered when assessing the feasibility of implementing a dual water reticulation
system in South Africa (Table 17). The three key issues highlighted by decision-
makers were technical/engineering, public health and safety, and economics and
these key issues represent the goals to be achieved when selecting a greywater
treatment unit from amongst a selection of units.

Table 17. Decision-makers’ ranking of key issues to be considered when

assessing the feasibility of implementing a dual water reticulation system in
South Africa
(Ilemobade et al., 2009a)
Key issues Decision-makers ranking Weight
Technical / Engineering 1 1.00
Public health and safety 2 1.13
Economics 3 1.26
Social acceptance 4 1.93
Legislation 5 2.13
Organisational capacity 6 2.40
Public education 7 2.43

Within the framework, the process of evaluating each greywater treatment units is as
follows:
i. Each criteria within each key issue is scored using a scale of 0 (low), 1(moderate)
and 2(high);
ii. The score for each criterion is multiplied by its weight to obtain a weighted real
score (equation 5.1):
Weighted _ Re al _ Score  ScorexWeig ht ….5.1

iii. For each key issue, the weighted mean of the real scores is calculated (equation

5.2):
Weighted _ Re al _ Score
Weighted _ Mean _ of _ Re al _ Scores  ….5.2
Number _ of _ items _ in _ the _ key _ issue

95
iv. For the framework, the aggregate of the weighted mean of the real scores is

calculated (equation 5.3). This aggregate ranges between 0.00 (most preferred
package plant) and 6.78 (the least preferred package plant):
No _ of _ key _ issues
Aggregate _ of _ Weighted _ Means  Weighted _ Mean _ of _ Re al _ Scores …5.3
i 1

Table 18. Framework for evaluating greywater treatment units for toilet
flushing (the Technical key issue)
CRITERIA SCORES WEIGHT LITERATURE
0 1 2 REFERENCE
TECHNICAL KEY ISSUE
Treatment Secondary Primary 1.00 Li et al., 2009
Technology and tertiary Treatment
treatment only/ no info
Pre- Yes No / no info 1.00 Li et al., 2009
treatment
and storage
Disinfection Yes No / no info 1.00 Li et al., 2009
Operating 0.5-100 0.5-10 10- 1.00 Landcom's WSUD
range (kl/d) (Covers a (household) 100(clustered strategy (2003)
wide range 4- development<=
500 PE) 500 PE) / no
info
Footprint 1.2-124 1.2 to 3 3- 1.00 Landcom's WSUD
(m²) (Covers a (household) 124(clustered strategy (2003)
wide range 4- development<=
500 PE) 500 PE) / no
info
Life cycle >= 25 25 to 15 < 15 / no info 1.00 USEPA (2007) Code
(years) of Practice for single
houses and WRC
report No 1539/1/06
Level of Low Moderate High / no info 1.00 USEPA (2007) Code
operator skill of Practice for single
houses and WRC
report No 1539/1/06
Ease to Yes No / no info 1.00 USEPA (2007) Code
upgrade of Practice for single
houses and WRC
report No 1539/1/06
WEIGHTED MEAN OF REAL SCORES

96
Table 19. Framework for evaluating greywater treatment units for toilet
flushing (the Economic key issue)
CRITERIA SCORES WEIGHT LITERATURE
0 1 2 REFERENCE
ECONOMIC KEY ISSUE
Cost (Rand) < 50 000 50 000 -100 > 100 000 / no 1.26 Landcom's WSUD
000 info strategy (2003)
Operating < 5000 5000 to 10 >10 000 / no 1.26 Landcom's WSUD
cost 000 info strategy (2003)
(Rand/year)
WEIGHTED MEAN OF REAL SCORES

Table 20. Framework for evaluating greywater treatment units for toilet
flushing (the Public health and safety key issue)
CRITERIA SCORES WEIGHT LITERATURE
0 1 2 REFERENCE
PUBLIC HEALTH AND SAFETY (I.E. WATER QUALITY) KEY ISSUE
BOD (mg/l) <= 10 > 10 / no info 1.13 USEPA (2007)
Standard
COD (mg/l) < 75 > 75 / no info 1.13 DWAF, 2004a;
Prathapar et al.
(2006)
Total < 30 > 30 / no info 1.13 German Standard
Suspended
Solids (mg/l)
Turbidity <= 2 > 2 / no info 1.13 USEPA (2007)
(NTU) Standard
Free chlorine >1 <=1/ no info 1.13 USEPA (2007)
(mg/l) Standard
PH 6 to 9 no info 1.13 DWAF, 2004a;
USEPA (2007)
Standard
Total Non detected Detected / no 1.13 USEPA (2007)
Coliform info Standard
E. coli Non detected Detected / no 1.13 DWAF, 2004a;
info USEPA (2007)
Standard
WEIGHTED MEAN OF REAL SCORES
AGGREGATE OF THE WEIGHTED MEANS

5.4. Results and discussion on the application of the framework

Table 21 represents the results of the evaluation of the 10 greywater treatment units
for which detailed information was available. The identities of the different
manufacturers / suppliers whose units were evaluated, are not mentioned for the
sake of confidentiality. Most manufacturers / suppliers responded by sending leaflets
of their plants with little information on different criteria, e.g. treated effluent quality.

97
Hence, where no responses were given to specific criteria, the highest score was
assigned.

Technical
The Technical key issue refers to the treatment technology employed by the
package plant.
 The C, A and G units scored the lowest in this key issue. Most of their treatment
is biological followed by disinfection;
 An advantage of the C and A units is that they cover a wide operating range, i.e.
from the household level to clustered developments
 The G unit can only treat effluent produced by 35 people;

Economics
Cost determines if a package plant will be affordable. Cost is directly related to the
treatment technology employed and hence, the more complex the treatment
process, the more expensive the treatment unit will likely be. Actual costs were
obtained from A, B, C, F, H, and D;
 The B, A, and D units scored the lowest in this key issue;
 Costs of operating the above units (e.g. disinfection and electricity) range
depending on local circumstances.

98
Table 21. Results of the evaluation of 10 grey/waste water treatment units
UNIT A UNIT B UNIT C UNIT D UNIT E UNIT F UNIT G UNIT H UNIT I UNIT J
CRITERIA WEIGHT
REAL SCORE x WEIGHT
TECHNICAL
Technology 1.00 0 1 0 0 1 0 0 1 0 2
storage 1.00 1 1 0 0 1 0 0 1 0 2
Disinfection 1.00 0 0 0 0 1 0 0 0 0 2
Operating range (kl/d) 1.00 0 1 0 2 1 1 1 1 2 2
Footprint (m²) 1.00 1 1 0 2 1 2 2 2 2 2
Life cycle (years) 1.00 1 1 1 2 2 2 0 2 2 2
Level of operator skill 1.00 0 0 0 0 0 0 0 2 2 2
Ease to upgrade 1.00 0 0 0 1 0 0 0 2 2 2
WEIGHTED MEAN 0.38 0.63 0.13 0.88 0.88 0.63 0.38 1.38 1.25 2.00
ECONOMICS
Cost (Rand) 1.26 0 0 1.26 0 0 1.26 2.52 1.26 2.52 2.52
Operating cost
(Rand/year) 1.26 0 0 1.26 0 1.26 2.52 2.52 2.52 2.52 2.52
WEIGHTED MEAN 0.00 0.00 1.26 0.00 0.63 1.89 2.52 1.89 2.52 2.52
PUBLIC HEALTH AND SAFETY (i.e. WATER QUALITY)
BOD (mg/l) 1.13 1.13 1.13 0 1.13 1.13 1.13 1.13 1.13 1.13 2.26
COD (mg/l)p 1.13 0 1.13 0 1.13 1.13 0 1.13 1.13 1.13 2.26
Solids (mg/l) 1.13 0 1.13 0 1.13 1.13 0 1.13 1.13 1.13 2.26
Turbidity (NTU) 1.13 1.13 1.13 0 1.13 0 0 1.13 1.13 1.13 2.26
Free chlorine (mg/l) 1.13 1.13 1.13 0 1.13 1.13 0 1.13 1.13 1.13 2.26
PH 1.13 0 0 0 1.13 0 0 1.13 1.13 1.13 2.26
Total Coliform 1.13 0 0 0 1.13 0 0 1.13 0 0 2.26
E.Coli 1.13 0 0 0 1.13 0 0 1.13 0 0 2.26
WEIGHTED MEAN 0.42 0.71 0.00 1.13 0.57 0.14 1.13 0.85 0.85 2.26
AGGREGATE OF THE
WEIGHTED MEANS 0.80 1.33 1.39 2.01 2.07 2.66 4.03 4.11 4.62 6.78

SCORE RANGE 0.00 3.39 6.78

99
Public health and safety (i.e. water quality)
Public health and safety was evaluated using the quality of the treated effluent
released from each package plant. Information from several manufacturers/suppliers
was lacking in this regard. This may be because there is limited information
regarding most package plants in this regard or for some reason,
manufacturers/suppliers were cautious releasing such information.
 C, F and A scored the lowest in this key issue
 Unit F does not specifically mention that its plant’s treated effluent can be used
for toilet flushing. However, their effluent may be used for toilet flushing as quality
parameters are within DWAF (2004a) and international guidelines

Selection of appropriate greywater treatment unit

There is no simple formula for selecting a greywater unit because of the trade-offs
that need to be made between the technical, economics and public health and safety
key issues:
 Units A, B and C achieved the lowest scores in the framework and were
therefore, the most favoured for the pilot project. Certain points of note were:
a. Unit C:
 is sensitive to influent quality. Hence, a drastic change in influent quality
would negatively affect effluent quality;
 is aesthetic, compact, and an automated system which produces effluent that
can also be used for irrigation;
 is three times the cost of Units A and B;
 was recommended by users of this installation.
b. Unit B:
 uses a filter/sieve with Bromine disinfection cubes, The tank is sized to ensure
that treated greywater is not stored in the pump chambers for more than 24
hours – thereby reducing the possibility of pathogen growth;
 has the lowest cost amongst the three;
 employs indigenous technology;
 was recommended by previous users.
c. Unit A:
 is the plant unit with the lowest score on the framework;

100
  employs indigenous technology;
 water quality parameters were evaluated based on information provided by
the manufacturer/supplier;
 was recommended by previous users.

Manufacturers / suppliers of Units A and B were approached to provide quotes for

the installation of the greywater units at the proposed sites (next chapter). Unit B
provided the most suitable quotes and guarantees and was thus awarded the
contract to install the greywater reuse units for toilet flushing at the pilot sites.

101
 6. IMPLEMENTATION OF THE PILOT GREYWATER REUSE SYSTEMS FOR
TOILET FLUSHING

This chapter introduces the sites where the pilot systems were located and
documents some aspects of the implementation and monitoring of the pilot
greywater reuse systems for toilet flushing. Other aspects which are reported in
detail are documented in the subsequent chapters of the report. The implementation
of the greywater reuse systems at only two sites was decided by the available
project funds and the results of the preliminary perception surveys which were
carried out in 2008 (details in Chapter 6).

6.1. Location of the pilot systems

6.1.1. The School of Civil and Environmental Engineering, WITS

The building (Figure 14) housing the School of Civil and Environmental Engineering
at the University of the Witwatersrand (WITS) currently houses the first greywater
reuse system. On a peak working day of the 2011 academic calendar, the building
typically houses about 36 staff (academic and support services) and approximately
450 students. There are 7 bathrooms housing a total of 12 Toilets, 1 shower and 12
hand basins within the building. Two male and 3 female toilets (mostly used by
students) are located in 2 bathrooms at the south side of the building while 5 male
and 2 female toilets (mostly used by staff) are located in 5 bathrooms at the north
side of the building. Except for 2 north side female bathrooms which house only 1
hand basin each, the other bathrooms house 2 hand basins each. WITS is
representative of a typical high-density educational (non-residential) water user.

102
Figure 14. View of the (Left) south side and (Right) east side (main entrance) of
the School of Civil and Environmental Engineering, WITS

A key driver for the implementation of the first pilot greywater system within WITS
was the excitement expressed by most staff and students in the 1st perception
survey carried out in 2008 (section 6.2.1) concerning greywater reuse for toilet
flushing. There were several challenges however encountered prior to and during the
installation of the greywater reuse system for toilet flushing within the building and
these included:
i. outdated drawings of the different services making it difficult to determine exactly
where different services were located within the building. Hence, most building
reconstructions were carried out with outmost care resulting in longer periods of
time undertaking certain tasks;
ii. retrofitting the greywater system in the 70 year old building which resulted in the
following difficulties
a. finding available space for the greywater unit;
b. determining the optimal location for the system given the constraints of the
available locations;
c. the presence of permanent structures which obstructed the preferred path of
the unit and hence the need to move large items; and
d. a major source of greywater (i.e. the shower) is located on the ground floor
with the drainage pipe embedded into the ground floor slab.

103
Since greywater could only be collected from hand basins, the estimated greywater
volumes generated and potential reuse for toilet flushing per day are calculated
below:
i. there is approximately 1 toilet flush per individual per working day within the
building ≈ about 486 flushes;
ii. for each flush, about 0.5 litres of potable water is used for hand washing in the
basin ≈ 243 litres of greywater generated per day;
iii. 486 flushes per working day for the 12 toilets ≈ 41 flushes per toilet per day ≈ 246

litres per cistern (average cistern size of 6 litres) per day; and
iv. the estimate above therefore adequately caters for greywater reuse for toilet

flushing in only 1 toilet.

It was therefore anticipated that the greywater generated would often be insufficient
to cater for toilet flushing in 2 toilets on a typical working day.

6.1.2. Unit 51A, Student Town, UJ Kingsway campus

Similar to WITS, a key driver for the implementation of the second pilot greywater
system within the University of Johannesburg was the excitement expressed by the
UJ leadership, residents of Student Town and residents of Unit 51A (section 6.2.1)
concerning greywater reuse for toilet flushing. Unit 51A, Student Town, University of
Johannesburg Kingsway campus (UJ) is a 16 female residence and one of several
units within Student Town. The layout of Student Town which provided the potential
for isolating a unit, made it an ideal site for the implementation of one of the pilot
greywater units. The ground floor and 1st floor of each unit has 8 rooms – each
allocated to 1 resident. Ablution and cooking facilities are communal – there are 2
toilets, 1 shower, 1 bath tub and 3 hand basins on each floor. Unit 51A has the
wastewater and rainwater drainage pipes located at the rear of the building, outside
the walls (Figure 15) and potable water is supplied to the unit via 1 pipe. Electricity
consumption within the unit is measured from 1 meter box.

104
Figure 15. The rear of Unit 51A, Student Town, University of Johannesburg

Some advantages in implementing the 2nd pilot greywater reuse system at the unit at
UJ included:
i. the ease to retrofit the greywater reuse system due to the central location of the
greywater drainage pipes on the outside of the building;
ii. the ease to harvest rainwater (roof gutters and downpipes were already installed)
to supplement greywater; and
iii. the potentially large quantities of greywater that may be collected for toilet

flushing from the 2 showers and 2 bath tubs within the unit.

Estimated greywater volumes generated per day and anticipated reuse were
calculated as follows:
i. estimated greywater volumes generated from showers and baths at about 50
litres per student ≈ 800 litres per day;
ii. estimated greywater volumes required for toilet flushing @ 4 flushes per student
per day (see section 6.3.2) using a 10 litre cistern ≈ 640 litres per day;
iii. hence, per day, it was estimated that there would be sufficient greywater for

flushing the 4 toilets within the unit

6.2. Implementation of the pilot systems

6.2.1. Implementation of the pilot greywater reuse system at WITS

Unit B emerged from Section 4.4. as the preferred greywater reuse unit for
105
installation at both sites. After lengthy consultations (due to the fact that the WITS
building was not originally intended for greywater reuse and thus, arriving at a
mutually satisfactory solution was difficult) and a lengthy period of registration and
administration with the university, installation of the greywater reuse system
commenced on the 23rd of November 2009. A schematic of the initial greywater
system and pictures are shown in Figures 16 and 17 respectively.

In the initial Unit B system, greywater was collected from 12 bathroom hand basins
and 2 laboratory hand basins within the building1. The greywater then passed
through two 2 mm sieves2 in series (Figure 17) (which are housed within a cylindrical
pipe3) and disinfected using 200 g Sanni Tabs4a (chlorine + bromine tablets) (Figure
17) which were inserted into the sieves once a week. The greywater was then stored
within a 200 litre greywater tank5 which houses 2 submersible pumps (each pump
was connected to a toilet – a male toilet on the ground floor and a female toilet
(Figure 17) on the first floor). When pressed, the bell switch6 (Figure 16 and 17),
which is attached to the wall close to the toilet cistern, activates the pump it is
connected to and conveys the greywater into the toilet bowl7 for flushing. A second
tank8, situated close to the greywater storage tank5, stores municipal water and
provides a back-up water supply to the greywater tank when greywater drops below
a prescribed level. An overflow pipe connected to the tank conveys excess
greywater to the sewer13a.
8

6
1 3
5 7
4a

13a

Figure 16. Schematic of the initial greywater system for toilet flushing at WITS

106
 13a

1
2

8
3
5

4a

Figure 17. (Top left) The initial Unit B greywater reuse system. (Top right) The 2
mm sieves that filter the greywater. (Bottom left) Samples of the 200 g Sanni
Tabs. (Bottom right) The female toilet connected to the greywater system

Prior to, during and after installation of the initial system, certain issues drove the
need for the initial greywater reuse system to be modified. These included:
i. blue or green cistern blocks4b (Figure 18) were inserted into the sieves weekly in
order to dye the greywater to make it aesthetic for users and to distinguish it from
potable water;

4b

Figure 18. Cistern blocks used to colour the greywater

107
ii. an additional back-up was added to the system (Figure 19) – the toilet cistern9
which previously used municipal potable water supply was not disconnected. It
was simply turned off using a valve10. Hence, in the event of greywater supply
failure, the municipal supply may be turned on at the valve and the toilet will
revert to its former use;

10

Figure 19. Additional backup measure in the event of greywater supply failure

iii. unknowingly, the laboratory basins were used for washing dishes and disposing

cleaning fluids. This unfortunately led to the introduction of foods, cleaning

chemicals, dirt, fats and oils within the sieves (Figure 20 -left) and greywater tank
and resulted in unpleasant greywater odours and colour during the first few
weeks of operation. When this problem was identified, posters were placed near
the laboratory basins and an awareness session was held within the school. In
addition, strainers were installed as a first barrier at the basin to prevent food and
other materials from entering into the greywater system. Initially, these
interventions made a significant difference to the physical quality (colour and
smell) of the greywater (Figure 20 – left and centre). However over time, foods,
fats, etc. continually entered into the greywater system and consequently, all the
laboratory basins were disconnected from the greywater system. This made a
significant difference to the quality of the greywater (see Figure 20 – right).

108
Figure 20. The sieves a few days before the awareness session (Left); after the
awareness session (Centre); and after disconnecting the laboratory basins
(Right)

iv. the need to improve the disinfection of the greywater through the installation of

inline chlorine capsules11 on the greywater collection pipes (Figure 21);

11

11

Figure 21. Inline chlorinators installed to improve disinfection of the greywater

v. the creation of a diversion12 (Figure 22) to allow the greywater system to be shut
down during major maintenance actions or university holidays. The diversion
conveys the greywater to the sewer without it passing through the greywater
system and thus prevents greywater retention in the tank.
13b
vi. the creation of an additional overflow pipe (Figure 22) to the sewer in the event
that a blockage occurred in the sieves during operation.
vii. the installation of meters to measure the electricity consumption of the pumps.

Based on the above, the initial Unit B greywater reuse system (Figure 16) was
modified to that shown in Figure 22.
109
 8
9
6
11
1 3
5 7
4b
12

13b 13a

Figure 22. The modified and current schematic of the greywater reuse system
for toilet flushing at WITS

6.2.2. Implementation of the pilot greywater reuse system at UJ

The installation of the greywater reuse system at UJ (Figure 23) commenced in April
2010 and was similar to the system installed at WITS, but for the following
differences:
 Initially, greywater was sourced from the 2 showers, 2 baths and 6 hand basins
within the unit. Subsequently, to avoid food, grease, etc. contamination as
experienced at WITS, the hand basins were disconnected;
 A rainwater harvesting system was installed as the primary water supply backup
to the greywater tank. The secondary backup supply from the municipal potable
water supply system was at 2 points – a valve connected to the toilet cisterns as
was done at WITS and regulated supply into the rainwater tank14;
 The greywater tanks, collection pipes and sieves were buried in the soil within
the enclosure behind the unit to allow for the collection of greywater from the
ground floor bath and shower;

The schematic of the current greywater system at UJ is shown below.

110
 14 8
9
6
11
1 3
5 7
4b
12

13b 13a

Figure 23. Schematic of the current greywater system for toilet flushing at UJ
1
Greywater collection from 2 bath tubs and 2 showers within the unit;
3
The cylindrical pipe housing the two 2 mm sieves in series;
4b
Cistern blocks inserted weekly into the sieves to dye the greywater;
5
The 200 litre greywater tank;
6
The bell switch;
7
The toilet bowl which flushes with disinfected greywater;
8
Potable water backup to the rainwater tank;
9
The greywater toilet cistern which is retained to ensure the toilet can revert to
potable water flush if there is greywater supply failure;
11
The chlorinators which provide disinfection to the raw greywater;
12
The diversion to allow the greywater system to be maintained or shut down during
university holidays;
13a
An overflow pipe from the greywater tank to the sewer;
13a
An overflow pipe from the filter to the sewer;
14
A rainwater harvesting system (filters, pipes and tank) providing primary backup
water supply to the greywater tank.

111
7. PERCEPTIONS, AWARENESS AND EDUCATION REGARDING GREYWATER
REUSE FOR TOILET FLUSHING WITHIN UCT, WITS AND UJ

Successes in the implementation of dual water reticulation systems have been

hinged on several factors including the positive attitudes of communities towards
reuse and community participation in the planning and implementation of reuse
projects (Po et al., 2003). Several reuse schemes in the United States of America
(e.g. the San Diego water repurification project and the San Gabriel Valley
groundwater recharge project) failed primarily due to negative attitudes and/or lack of
community participation. Some projects were redesigned in the United States of
America (i.e. the California Bay water recycling programme) and Australia after
strong opposition from local communities (Po et al., 2003). Several factors,
recognised to affect public attitudes to reuse schemes include perceived risks to
health and degree of human contact (Kantanoleon et al., 2007; Hurlimann and
McKay, 2007; Friedler et al., 2006; Po et al., 2003; and Hartley, 2003). Table 22
shows the levels of opposition to reclaimed water reuse from different surveys
carried out in the past.

Table 22. Opposition from respondents (%) to specific uses of recycled water
in different surveys
(Po et al., 2003)

While the public may be willing to accept greywater reuse, water

authorities/regulators are usually more cautious. Two factors stand out for this: the
112
potential public health risks involved in reuse and the costs of treatment. Associated
with public health is the level of public awareness about reuse, and the monitoring
and mitigation systems that should be in the event of system failure. In terms of cost,
it is estimated that the costs incurred by a municipal authority to treat and reticulate
treated non-potable water far exceeds the costs incurred by individual households
who install simple devices to divert untreated greywater onto their gardens.

This chapter summarises the processes and results from perception surveys carried
out to monitor evolving perceptions of potential and actual beneficiaries of the pilot
greywater reuse systems for toilet flushing. While perceptions were being monitored,
awareness/education campaigns were also carried out and this chapter also
documents the methods employed to achieve this process and some observed
results.

7.1. Perception survey methodology

7.1.1. Objectives of the perception surveys

The perception surveys undertaken in this study were aimed at determining:

i. potential and actual respondents’ perceptions to reusing greywater for toilet/urinal
flushing prior to implementation. Results from these surveys assisted in
identifying the preferred locations for the pilot systems to be implemented, and
the key issues that needed to be addressed before, during and after
implementation;
ii. actual respondents’ perceptions to reusing greywater for toilet/urinal flushing
immediately after implementation of the system; and
iii. actual respondents’ assessment of the pilot systems after extended use of the

greywater system for toilet/urinal flushing.

7.1.2. Structure of the perception survey questionnaires

Po et al. (2003) recommend some factors that may influence the acceptance of a
water reuse project. In order to garner the relevant perceptions of respondents

113
towards greywater reuse for toilet flushing, the questionnaires were developed using
several of these factors, i.e.:
i. socio-demographics;
ii. disgust or “yuck”;
iii. perceptions of risk associated with using recycled water;

iv. the specific uses of recycled water;

v. the sources of water to be recycled;

vi. the issue of choice;

vii. trust and knowledge;

viii. attitudes towards the environment;

ix. environmental justice; and

x. the cost of recycled water;

Three (3) questionnaires were developed (see Appendices B1, B2 and B3):
i. Questionnaire 1 solicits respondents’ perceptions to reusing greywater for
toilet/urinal flushing prior to and immediately after greywater system
implementation;
ii. Questionnaire 2 follows up on some items in Questionnaire 1 and solicits
respondents’ perceptions regarding their levels of satisfaction with the system
about 3 months after implementation;
iii. Questionnaire 3 follows up on some items in Questionnaires 1 and 2 and

requests respondents’ to assess the system about 7 months after

implementation.

The first section of each questionnaire has a number of statements requiring

respondents to select the option that is most applicable to them using the 5-point
scale provided, i.e. Strongly agree, Agree, Neutral, Disagree, and Strongly disagree.
The next section is open-ended and requests respondents to either list any reasons
(personal, cultural, religious or otherwise) why they may not use treated greywater
for toilet/urinal flushing or garden watering, or make comments. The third section
solicits socio-demographic data, e.g. age, status at university, etc.

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7.1.3. Administration of the questionnaires

Typically, each session with the respondents started with the administration of the
relevant questionnaires in hard copy form. This was done in order to garner the
perceptions of respondents prior to any awareness was carried out. In this form, the
initial perceptions of respondents were not tainted by the information subsequently
presented. Only after respondents had completed the filling of the questionnaires did
the project team proceed with providing information, etc.

7.1.4. Background and profile of respondents

The questionnaires were administered to the following respondents at the indicated

times (Table 23):

Table 23. Summarised profile of respondents

Year Questionnaire Respondents Number
Questionnaire 1 (prior to the WITS (students and staff at the School of
253
implementation of the greywater Civil and Environmental Engineering)
system). Results from these UJ (a random sample of students) 103
surveys assisted in identifying
2008 the preferred locations for the
pilot systems to be implemented, UCT (a random sample of students from 3
and the key issues that needed university residences – University House, 104
to be addressed before, during Varietas and Forest Hill)
and after implementation.
UJ (Female students residing at the proposed
Questionnaire 1 (prior to the
university residence, Unit 51A, Student Town,
2009 implementation of the greywater 13
and some members of the Student Town
system)
council)
Questionnaire 1 (immediately
UJ (beneficiaries of the greywater reuse
2010 after the implementation of the 14
system)
greywater system)
Questionnaire 1 (immediately WITS (a random sample of undergraduate
2010 after the implementation of the students at the School of Civil and 139
greywater system) Environmental Engineering)
2010 Questionnaire 2 (about 3 months WITS (a random sample of undergraduate
after implementation of the students at the School of Civil and 120
greywater system) Environmental Engineering)
2010 Questionnaire 2 (about 3 months
UJ (beneficiaries of the greywater reuse
after implementation of the 13
system)
greywater system)
2010 Questionnaire 3 (about 7 months WITS (a random sample of undergraduate
after implementation of the students at the School of Civil and 168
greywater system) Environmental Engineering)
2010 Questionnaire 3 (about 7 months
UJ (beneficiaries of the greywater reuse
after implementation of the 15
system)
greywater system)

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7.2. Perception survey results

Respondents’ perceptions for each questionnaire using several of the factors listed
in Section 7.1.2. are shown below:

7.2.1. Location of the pilot greywater systems

Potential respondents at the universities of Cape Town, the Witwatersrand and
Johannesburg were surveyed using the 1st questionnaire. Universities were
proposed as potential locations for the pilot systems for logistical reasons – the
researchers on the project were from the 3 universities and there was the perceived
ease to obtain approval for, implement and monitor the systems due to the
researchers’ proximity to the systems.

As indicated, the questionnaires were administered for a number of reasons

including assisting to identify the preferred locations for the pilot systems to be
implemented. Relevant management at the University of Cape Town declined the
offer to have a pilot system implemented on their campus due to other water saving
interventions which had recently been carried out. The appropriate WITS (School of
Civil and Environmental Engineering) and UJ (Vice-chancellor’s office)
managements were however elated about the implementation of the pilot systems at
the locations described in section 5.1. After the 1st questionnaires were administered
at Student Town in Unit 51A was selected as the preferred location.

7.2.2. Socio-demographics

Some demographic factors (Po et al., 2003) have been identified in reuse studies to
be influential in public perception of water reuse. For example, McKay & Hurlimann
(2003) predicted that the greatest opposition to water reuse schemes would be from
people aged 50 years and over. As a result, they recommended education and
information campaigns to target this specific age group. Some surveys in California
and Colorado, USA (cited in Hartley, 2003) further indicated that “older” women
tended to be less supportive of potable water reuse. In contrast, Jeffrey (2002) found
no significant variation in public support for greywater reuse across gender, age or

116
socio-economic groups. Sydney Water’s (1999) study indicated differences in the
responses of participants from different genders, levels of education, place of
residence, and language spoken. No discernible differences were, however, found in
the respondents from different age groups. In early potable reuse research in
Australia (Hamilton and Greenfield, 1991), it was suggested that without prior
exposure to negative reuse information, a person who had a higher level of
education, was male and had no aversion to change, was more likely to accept
potable reuse.

For the 2008 cohort of respondents, statistical analysis of the data generated from
responses to the 12 statements in the first section of the 1st questionnaire produced
three broad categories of responses: ‘Comfort levels’, ‘Concern levels’ and ‘Other’
(see Table 24). The discussion below is based on the ‘Comfort levels’ and ‘Concern
levels’ categories. The ‘Other’ category did not statistically present any significant
difference from the ‘Comfort levels’ category and is hence omitted from the
discussion.

Table 24. Socio-demographic response categories

CATEGORY: ‘Comfort levels’

Using treated greywater for toilet/urinal flushing or garden watering will have a positive impact on the
environment
Using treated greywater for toilet/urinal flushing or garden watering will make our limited drinking water
resources go further
I am comfortable using treated greywater for toilet/urinal flushing
I am comfortable using treated greywater originating from other buildings for toilet/urinal flushing or
garden watering
I am comfortable for a dual water distribution system to be installed where I currently reside
I am comfortable for a dual water distribution system to be installed at the School building
If a dual water distribution system is installed at the School or my residence, I trust the relevant
university authorities will ensure that the treated greywater used is safe for toilet/urinal flushing or
garden watering
CATEGORY: ‘Concern levels’
I am concerned about people getting sick from using treated greywater for toilet/urinal flushing
I am concerned about people getting sick from using treated greywater for garden watering
Using treated greywater for toilet/urinal flushing or garden watering is disgusting
I will only be prepared to use treated greywater for toilet/urinal flushing or garden watering during a
drought or water shortage
CATEGORY: ‘Other’
I am comfortable using treated greywater for garden watering

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A summary of the socio-demographic responses garnered are listed below:
i. Age groups:
 In relation to ‘Comfort levels’, the average response of the median of the ’15-
21 yrs’ (1.8333) was slightly lower than that for the ’22 yrs and older’ (2.0000).
This implies that 50% of the ’15-21 yrs’ were generally more comfortable
about greywater reuse than the same percentage of the ’22 yrs and older’.
Comparing the 75th percentile for both groups however interprets otherwise.
 The degree of concern about greywater reuse expressed by the ’15-21 yrs’
(median of 2.5000)) was generally less than that for the ’22 yrs and older’
(median of 2.7500).
ii. Status:
 In relation to ‘Comfort levels’, the average response of the median for the
’Undergrad’ (1.8571) was lower than that for the ’Other’ (2.1429). The ‘Other’
represents postgraduate students, academics and support staff. The same
applied while comparing the average response for the 75th percentile of both
groups. An implication of these results is that the ‘Undergrad’ group are in
general, more comfortable about greywater reuse than the ‘Other’. Assuming
the majority of the ’15-21 yrs’ are ‘Undergrad’, the implication in the latter
sentence correlates positively with the median results presented for the
different age groups in (i) above.
iii. Living in university residence:

 In relation to ‘Comfort levels’, the average response of the median for those
living in university residence (2.0000) was higher than that for those not living
in university residence (1.8000). The same applies while comparing the
average response for the 75th percentile of both groups. An implication of
these results is that those not living in university residence were in general,
more comfortable about greywater reuse than those living in university
residence.
 The implication stated in the above paragraph should result in those living in
university residence being more concerned about greywater reuse than those
not living in university residence. The analysis confirms this with the average
response of the median of those living in university residence (2.7500) being
higher than those not living in university residence (2.5000).

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iv. Gender:

 In relation to ‘Comfort levels’, the average responses of the median for ‘Male’
and ‘Female’ respondents were the same (1.8571). Also, there was a
negligible difference in the average responses of the 75th percentile for the
genders. This implies that in general, no difference in ‘Comfort levels’
pertaining to greywater reuse exists between the genders.
 A marginal difference does however exist between the genders in terms of
‘Concern levels’ – the average response of the median for ‘Female’ (2.5000)
was less than for the ‘Male’ (2.7500). This implies females may be generally
less concerned about greywater reuse than males.
v. Racial background:
 In relation to ‘Comfort levels’, the ‘White’ racial category seemed generally
more comfortable (median value of 1.5000) about greywater reuse than the
‘Other’ (representing Asian and Coloured) (median value of 2.0000) and
‘Black’ (median value of 2.0000) racial categories.
 The ‘Black’ racial category generally expressed more concern (median value
of 3.0000) about greywater reuse than the ‘Other’ (median value of 2.7500)
and ‘White’ (median value of 2.0000) racial categories.

7.2.3. Disgust or “yuck”

There was overwhelming disagreement to the statement “Using treated greywater for
toilet/urinal flushing or garden watering is disgusting” from the respondents (Table
25). Of particular note is the significant increase in disagreement between the
responses prior to and immediately after implementation. This could imply an
overwhelming appreciation for the concept of greywater reuse for toilet/urinal
flushing even after implementation when certain problems were experienced.

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Table 25. Using treated greywater for toilet/urinal flushing or garden watering
is disgusting
Scale Prior to implementation of the Immediately after About 3 months About 7 months
greywater system implementation of after after
the greywater implementation implementation
system of the greywater of the greywater
system system

WITS UCT – UJ – UJ – WITS – UJ – WITS – UJ – WITS – UJ –

– 2008 2008 2008 2009 2010 2010 2010 2010 2010 2010
Strongly 16.00
agree 4.5% 4.0% 7.1% % 1.5% 0.0% - - - -
Agree 11.1 15.00
7.3% 7.0% % % 5.2% 7.1% - - - -
Neutral 26.3 15.00
17.5% 18.0% % % 17.9% 28.6% - - - -
Disagree 40.4 46.00
40.2% 45.0% % % 33.6% 42.9% - - - -
Strongly 15.2
disagree 30.5% 26.0% % 8.00% 41.8% 21.4% - - - -

7.2.4. Perceptions of risk associated with reusing greywater

Perceptions of risk are often related to public health issues from reusing wastewater.
People may perceive the reuse of greywater to be too risky because (i) the use of
the water source is not natural (ii) it may be harmful to people (iii) there might be
unknown future consequences (iv) their decision to use the water may be
irreversible, and (v) that the quality and safety of the water is not within their control.

Responses to the statements “I am concerned about people getting sick from using
treated greywater for toilet/urinal flushing” or “I am concerned about my health when
I use the toilet that flushes with greywater” are shown in Table 26. On average,
about 40% of respondents were concerned and about 40% unconcerned about
greywater reuse for toilet flushing at WITS (2008 and 2010) and UCT (2008) prior to
implementation. At UJ however, the percentages concerned, were much higher
(average of 65% for 2008 and 2009) than at WITS and UCT. Immediately after
implementation at UJ in 2010, the female residents recorded a percentage of
concern (50%) which was significantly lower than the results for 2008 and 2009. This
may have resulted from an increased level of confidence in the project team to
ensure that the greywater system is safe and hygienic for their use. It must however
be noted that the 2010 UJ cohort were not entirely the same residents as those in

120
the unit in 2009 and 2008. Overall, the results underscore the need for the project
team to ensure that the implemented greywater reuse systems are consistently
hygienic.

Table 26. I am concerned about people getting sick from using treated
greywater for toilet/urinal flushing
Scale Prior to implementation of the Immediately after About 3 months About 7 months
greywater system implementation after after
of the greywater implementation implementation
system of the greywater of the greywater
system* system
WITS UCT – UJ – UJ – WITS UJ – WITS – UJ – WITS – UJ –
– 2008 2008 2008 2009 – 2010 2010 2010 2010 2010 2010
Strongly 46.00
agree 14.3% 21.4% 35.0% % 11.5% 7.1% 3.5% 30.8% - -
Agree 18.00
19.1% 19.4% 30.1% % 28.8% 42.9% 17.4% 7.7% - -
Neutral 27.00
24.7% 17.5% 21.4% % 15.1% 7.1% 16.5% 23.1% - -
Disagree 31.1% 35.0% 9.7% 9.00% 33.1% 21.4% 33.0% 23.1% - -
Strongly
disagree 10.8% 6.8% 3.9% 0.00% 11.5% 21.4% 29.6% 15.4% - -
*
The statement within the questionnaire reads “I am concerned about my health when I use the toilet
that flushes with greywater”

7.2.5. The specific uses of recycled water

In Table 27, a significant percentage of the WITS and UCT respondents were
comfortable with using treated greywater for toilet flushing. For WITS, this trend is
consistent prior to, immediately after and after about 3 months of use. At UJ however
after 3 months of use, respondents responded less enthusiastically as they had done
prior to and immediately after implementation. Certain operational issues at UJ (e.g.
turbid greywater in the toilet bowl due to scum and the ring of scum that develops
above the greywater level within the toilet bowl, unpleasant smells resulting from a
lack of regular maintenance, and backflow problems from the 1st floor drains into the
ground floor bath and shower) resulted in the dampened response to the statement.

In comparison to garden watering, most respondents preferred toilet flushing. Some

comments made to this effect include:
 “I am a bit reluctant to use it for garden watering as this might have a negative
impact on the plants due to the chemicals used during processing. However for
toilet flushing, I don’t have a problem”
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 “I am very concerned about using greywater for gardening because sometimes
people drink water that they use to water plant, and it will be a little bit unsafe”
 “My only concerns are watering vegetable gardens ……and as far as the dual
system goes for residential areas, that people and more especially children will
be aware of the difference. That the greywater supply outside will be out of reach
of children”

Table 27. I am comfortable using treated greywater for toilet/urinal flushing

Scale Prior to implementation of the Immediately About 3 About 3
greywater system after months after months after
implementation implementation implementation
of the of the of the
greywater greywater greywater
system system system*
WITS – UCT – UJ – UJ – WITS UJ – WITS UJ – WITS UJ –
2008 2008 2008 2009 – 2010 2010 – 2010 2010 – 2010 2010
Strongly
agree 61.1% 46.6% 34.0% 46.00% 56.1% 42.9% 56.3% 7.7% 50.8% 7.7%
Agree 24.6% 27.2% 34.0% 23.00% 30.9% 35.7% 31.9% 38.5% 36.4% 38.5%
Neutral 9.9% 20.4% 20.4% 31.00% 7.2% 21.4% 7.6% 30.8% 8.5% 30.8%
Disagree 3.2% 4.9% 5.8% 0.00% 5.0% 0.0% 4.2% 7.7% 3.4% 7.7%
Strongly
disagree 1.2% 1.0% 5.8% 0.00% 0.7% 0.0% 0.0% 15.4% 0.8% 15.4%
*
The statement within the questionnaire reads “I am comfortable using treated greywater originating
from the hand basins (WITS) / bath tubs and showers (UJ) within the building”

7.2.6. The sources of water to be recycled

Generally, people prefer reusing wastewater produced within their property as

opposed to wastewater generated elsewhere. In Table 28, a larger proportion of
WITS respondents are comfortable using greywater from other sources. In addition,
a larger proportion of the WITS respondents, after 3 months of using the system,
indicated comfort using greywater from the bathroom hand basins within the building.
On the other hand, the positive response is less at UJ for the 2008 and 2009
respondents with a higher proportion of respondents (in comparison with WITS)
strongly opposed to using greywater from other buildings. The same is also true for
responses to the level of comfort with using greywater from the baths and showers
within the unit after 3 months of using the system. Two factors are suspected at play
in the UJ responses, i.e. the respondents were all female who are very conscious of
personal hygiene and therefore cautious of technologies that may be seen to
threaten their expected hygienic expectations; and wastewater reuse systems in

122
peoples’ residences are typically viewed with higher suspicion as a result of its
proximity to residents’ ‘private space’ in comparison to reuse systems in non-
residential properties (this is confirmed in Section 7.2.2 iii).

Table 28. I am comfortable using treated greywater originating from other

buildings for toilet/urinal flushing or garden watering
Scale Prior to implementation of the Immediately About 3 About 7
greywater system after months after months after
implementation implementation implementation
of the of the of the
greywater greywater greywater
system system system
WITS – UCT – UJ – UJ – WITS UJ – WITS UJ – WITS UJ –
2008 2008 2008 2009 – 2010 2010 – 2010 2010 – 2010 2010
Strongly
agree 36.0% 24.0% 20.4% 15.00% 34.3% 28.6% - - - -
Agree 31.6% 31.7% 22.3% 23.00% 32.8% 28.6% - - - -
Neutral 22.5% 23.1% 22.3% 31.00% 17.9% 35.7% - - - -
Disagree 7.1% 11.5% 22.3% 31.00% 10.4% 7.1% - - - -
Strongly
disagree 2.8% 9.6% 12.6% 0.00% 4.5% 0.0% - - - -

7.2.7. The issue of choice

In relation to choice (Table 29), a higher proportion of WITS respondents (53% in

2008, 73% in 2010 immediately after implementation and 61%, 3 months after
implementation) and UCT were willing to consider greywater reuse for toilet/urinal
flushing or garden watering without the compulsion of a water shortage. With neutral
responses of about 10%, this skews the data in favour of WITS respondents willing
to consider reuse. UJ respondents depict an initial high percentage of willing
respondents prior to implementation (59% in 2009 and 64% in 2010) but this
percentage decreases significantly to 39%, 3 months after implementation. This
response increased the percentage of UJ 2010 respondents only willing to consider
greywater reuse during a water shortage from 21% to 46%. Similar to the response
to the statement “I am comfortable using treated greywater for toilet/urinal flushing”
in Section 7.2.5., the UJ 2010, 3 months after implementation response, is likely
attributed to the operational challenges/problems encountered at UJ (i.e. turbid
greywater in the toilet bowl due to scum and the ring of scum that develops above
the greywater level within the toilet bowl, unpleasant smells resulting from a lack of
regular maintenance, and backflow problems from the 1st floor drains into the ground
floor bath and shower);
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Table 30 also displays similar trends to that discussed above – WITS respondents
were generally comfortable for a greywater system to be installed where they resided
and in the future, while the high percentages of comfort recorded for UJ prior to (63%
in 2008 and 73% in 2009) and just after implementation (79%), decreases drastically
to about 15%, 3 months after implementation. Many of the 2010 respondents, who
were initially comfortable, became neutral 3 months after experiencing the system’s
operational problems.

Table 31 shows significant percentages of WITS respondents comfortable with the

installation of a greywater system at the school building.

In general, the results indicate a higher percentage of comfort with installing a

greywater reuse system for toilet flushing at a non-residential than residential
premises.

Table 29. I will only be prepared to use treated greywater for toilet/urinal
flushing or garden watering during a water shortage
Scale Prior to implementation of the Immediately About 3 About 7
greywater system after months after months after
implementation implementation implementation
of the of the of the
greywater greywater greywater
system system system
WITS – UCT – UJ – UJ – WITS UJ – WITS UJ – WITS UJ –
2008 2008 2008 2009 – 2010 2010 – 2010 2010 – 2010 2010
Strongly
agree 7.6% 10.7% 11.7% 25.00% 5.0% 0.0% 10.3% 23.1% - -
Agree 16.1% 11.7% 23.3% 8.00% 10.8% 21.4% 12.8% 23.1% - -
Neutral 17.7% 21.4% 28.2% 8.00% 10.8% 14.3% 15.4% 15.4% - -
Disagree 34.9% 40.8% 28.2% 34.00% 42.4% 42.9% 38.5% 38.5% - -
Strongly
disagree 23.7% 15.5% 8.7% 25.00% 30.9% 21.4% 23.1% 0.0% - -

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Table 30. I am comfortable for a dual water distribution system to be installed
where I currently reside
Scale Prior to implementation of the Immediately About 3 About 7
greywater system after months after months after
implementation implementation implementation
of the of the of the
greywater greywater greywater
system system* system
WITS – UCT – UJ – UJ – WITS UJ – WITS UJ – WITS UJ –
2008 2008 2008 2009 – 2010 2010 – 2010 2010 – 2010 2010
Strongly
agree 36.1% 17.3% 27.2% 9.00% 30.1% 42.9% 21.4% 7.7% - -
Agree 36.1% 39.8% 35.9% 64.00% 41.2% 35.7% 37.6% 7.7% - -
Neutral 17.4% 29.6% 22.3% 18.00% 11.8% 21.4% 23.1% 61.5% - -
Disagree 6.6% 6.1% 10.7% 9.00% 9.6% 0.0% 10.3% 15.4% - -
Strongly
disagree 3.7% 7.1% 3.9% 0.00% 7.4% 0.0% 7.7% 7.7% - -
*
The statement within the questionnaire reads “I would consider installing a greywater system in my
household one day”

Table 31. I am comfortable for a dual water distribution system to be installed

at the School of Civil and Environmental Engineering, WITS
Scale Prior to implementation of the Immediately About 3 About 7
greywater system after months after months after
implementation implementation implementation
of the of the of the
greywater greywater greywater
system system system
WITS – UCT – UJ – UJ – WITS UJ – WITS UJ – WITS UJ –
2008 2008 2008 2009 – 2010 2010 – 2010 2010 – 2010 2010
Strongly
agree 46.2% - - - 38.1% - - - - -
Agree 38.1% - - - 48.5% - - - - -
Neutral 10.5% - - - 10.4% - - - - -
Disagree 2.4% - - - 2.2% - - - - -
Strongly
disagree 2.8% - - - 0.7% - - - - -

7.2.8. Trust

A significant percentage of WITS responses prior to (88%), immediately after (84%)

and 3 months after implementation (76%) depict respondents confidence that the
relevant authorities will ensure that greywater is safe (Table 32). Although the
percentages are marginally lower, the same perception is mirrored at UCT (64% in
2008) and UJ (69% in 2009, 86% just after implementation, and 69% 3 months after
implementation).

125
Table 32. I trust the authorities will ensure that the treated greywater is safe for
toilet/urinal flushing
Scale Prior to implementation of the Immediately About 3 About 7
greywater system after months after months after
implementation implementation implementation
of the of the of the
greywater greywater greywater
system system* system
WITS – UCT – UJ – UJ – WITS UJ – WITS UJ – WITS UJ –
2008 2008 2008 2009 – 2010 2010 – 2010 2010 – 2010 2010
Strongly
agree 45.5% 20.4% - 54.00% 34.8% 64.3% 27.4% 23.1% - -
Agree 42.3% 43.7% - 15.00% 48.9% 21.4% 48.7% 46.2% - -
Neutral 7.7% 20.4% - 31.00% 15.6% 14.3% 20.5% 23.1% - -
Disagree 2.4% 11.7% - 0.00% 0.7% 0.0% 3.4% 7.7% - -
Strongly
disagree 2.0% 3.9% - 0.00% 0.0% 0.0% 0.0% 0.0% - -
*
The statement within the questionnaire reads “I am confident that the relevant authorities would
ensure that the treated greywater used for toilet flushing is safe”

7.2.9. Attitudes towards the environment

Prior to, immediately after and 3 months after implementation, a significant

percentage of respondents affirmed that greywater reuse will be beneficial to the
environment (Table 33).

Table 33. Using treated greywater for toilet/urinal flushing or garden watering
will have a positive impact on the environment
Scale Prior to implementation of the Immediately About 3 About 7
greywater system after months after months after
implementation implementation implementation
of the of the of the
greywater greywater greywater
system system* system
WITS – UCT – UJ – UJ – WITS UJ – WITS UJ – WITS UJ –
2008 2008 2008 2009 – 2010 2010 – 2010 2010 – 2010 2010
Strongly
agree 59.9% 43.6% 31.1% 54.00% 57.2% 71.4% 60.5% 53.8% - -
Agree 28.6% 43.6% 47.6% 46.00% 34.8% 28.6% 37.0% 38.5% - -
Neutral 7.1% 8.9% 11.7% 0.00% 5.1% 0.0% 2.5% 0.0% - -
Disagree 3.6% 2.0% 7.8% 0.00% 2.2% 0.0% 0.0% 7.7% - -
Strongly
disagree 0.8% 2.0% 1.9% 0.00% 0.7% 0.0% 0.0% 0.0% - -

7.2.10. Environmental justice

Perceived injustices prior to, during, or after the implementation of a reuse project
can result in project failure. Perceived injustices can arise from (Po et al., 2003):
i. the perception that low and/or medium income communities are targeted for

126
 reuse projects while higher income communities are not targeted;
ii. perceived unfairness in the decision making process.
iii. the lack of consultation or involvement of potential beneficiaries;

iv. the location of treatment plants close to residential areas. This may lead to

unpleasant smells and potential contamination. This is a highly contentious issue

for many households in Australia currently implementing treated wastewater
reuse;
v. community members feeling they are being targeted for water reuse initiatives
whereas water reuse projects should start with big water users such as industries
before domestic households.

Tables 34 and 35 address the 3rd bullet point. Complaints and suggestions voiced in
the questionnaires administered about 3 months after implementation of the
greywater system assisted in the improvements made to the system to reduce
unpleasant smells and improve the greywater colour. At WITS and UJ, there was an
overall significant increase in the percentage of respondents satisfied with the
reduction in unpleasant smells and improvement in colour. These increases have
positively influenced the average number of times respondents use the greywater
reuse toilets during each toilet event (Table 36)

Table 34. I am satisfied with the reduction in unpleasant smells emanating

from the greywater toilet while flushing.
Scale Prior to implementation of the Immediately About 3 About 7
greywater system after months after months after
implementation implementation implementation
of the of the of the
greywater greywater greywater
system system system
WITS – UCT – UJ – UJ – WITS UJ – WITS UJ – WITS UJ –
2008 2008 2008 2009 – 2010 2010 – 2010 2010 – 2010 2010
Strongly
agree - - - - - - 12.2% 23.1% 30.3% 33.3%
Agree - - - - - - 42.6% 23.1% 47.9% 46.7%
Neutral - - - - - - 33.0% 15.4% 19.4% 13.3%
Disagree - - - - - - 5.2% 23.1% 0.6% 6.7%
Strongly
disagree - - - - - - 7.0% 15.4% 1.8% 0.0%

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Table 35. I am satisfied with the improvement in the colour of the greywater.
Scale Prior to implementation of the Immediately About 3 About 7
greywater system after months after months after
implementation implementation implementation
of the of the of the
greywater greywater greywater
system system system
WITS – UCT – UJ – UJ – WITS UJ – WITS UJ – WITS UJ –
2008 2008 2008 2009 – 2010 2010 – 2010 2010 – 2010 2010
Strongly
agree - - - - - - 14.7% 23.1% 28.8% 13.3%
Agree - - - - - - 41.4% 38.5% 41.7% 53.3%
Neutral - - - - - - 33.6% 15.4% 23.9% 26.7%
Disagree - - - - - - 7.8% 15.4% 4.3% 6.7%
Strongly
disagree - - - - - - 2.6% 7.7% 1.2% 0.0%

Table 36. How often do you use the greywater toilet?

Scale Prior to implementation of the Immediately About 3 months About 7 months
greywater system after after after
implementation implementation implementation of
of the greywater of the greywater the greywater
system system system
WITS – UCT UJ – UJ – WITS – UJ – WITS – UJ – WITS – UJ –
2008 – 2008 2009 2010 2010 2010 2010 2010 2010
2008
Every time
(100%) - - - - - - 15.4% 0.0% 19.3% 0.0%
3 out of 4
times (75%) - - - - - - 22.1% 33.3% 22.9% 40.0%
2 out of 4
times (50%) - - - - - - 34.6% 25.0% 30.1% 40.0%
1 out of 4
times (25%) - - - - - - 22.1% 25.0% 21.1% 20.0%
Not at all
(0%) - - - - - - 5.8% 16.7% 6.6% 0.0%

7.2.11. The cost of recycled water

The paragraph below is based on a study by Ilemobade et al., (2009b). Hence, the
effect of the cost of recycled water was not assessed in this survey.
“Tariffs for non-potable water conveyed via dual water reticulation systems are
usually lower than potable water tariffs and this has encouraged non-potable water
reuse. In the CoCT (City of Cape Town), treated effluent tariffs in 2007 ranged from
7% to 40% of the potable water tariffs and this has encouraged several large users
of non-potable water (e.g. the Chevron oil refinery) to reuse treated effluent. The
percentage of willing respondents in the perception survey increased from 36% to
71% if tariffs for non-potable water were lower than for potable water. In the
modelling exercise where a treated effluent system replaced the existing potable

128
water supply system for toilet flushing, landscape irrigation, paving and masonry
production, cost savings of about 67% (R17,150,048) were achieved over 20 years”

7.3. Awareness and education

7.3.1. Awareness and education at WITS

In addition to the perception surveys discussed above, the following education and
awareness activities were carried out at WITS:
i. on the 26th of February 2010, a seminar regarding the pilot greywater system was
presented by 4th year students involved on the project. This seminar was
attended by students, staff and visitors to the school and was part of a showcase
of projects which were geared towards “greening” the building;
ii. shortly after the greywater system was implemented, brief awareness sessions
were held with the school’s technical staff and the 1st, 2nd, 3rd and 4th year
students of the School. These sessions were aimed at describing the system,
allaying fears due to the intermittent functionality of the system at the time, and
the unpleasant odours which were emanating from within the greywater tanks
due to decomposing foods, fat, oils and grease that had entered into the system
from the laboratory basins. Prior to these awareness sessions, the relevant
questionnaires were administered;
th
iii. Two groups of students undertook their 4 year investigational projects on the
greywater reuse system. These projects required the students to undertake a
series of tasks (e.g. surveys and awareness) which involved interaction with
students and staff;
iv. The greywater system is one of the exhibits annually showcased by the school to

visitors and potential students during its annual information days;

v. Size A3, A4 and A5 posters were put up within the building and bathrooms
(Figure 24 (a), (b), (c) and (d)). These posters provide awareness of the system
and describe how to use the system.

129
130
Figure 24 (1st). A5 posters placed in front of each hand basin; (2nd) A3 posters
placed above toilet cisterns; (3rd) A4 awareness posters about wastewater
reuse; (4th) One of the bathrooms displaying the above posters.

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vi. The greywater concept and system comprised a section (lectures, long essay

and exam) of a 4th year and postgraduate course. An excerpt of the 4th year exam
question is shown in the box below:

University of the Witwatersrand, Johannesburg

CIVN4006: Integrated Resources Management
EXAM: September 9, 2010
Question A1
In fulfilling its mandate to drive research to protect and conserve depleting water resources in South Africa and to
provide viable supplemental sources for future water demands, the Water Research Commission provided
funding for the installation of 2 pilot greywater recycling units at the WITS School of Civil and Environmental
Engineering and at Unit 51A (a 16 student residence), Student Town, the University of Johannesburg (UJ)
Kingsway campus. The purpose of these pilots is to determine the appropriateness and sustainability of
greywater recycling within urban communities in South Africa. At WITS, greywater refers to wastewater from only
bathroom hand basins and at UJ, greywater refers to wastewater from only showers and bath tubs.

Due to the sensitive nature of this project, provide a brief, yet concise write-up responding to the following
questions/statements:
i. Which resources are involved on this project?
ii. What are the potential constraints/limitations/challenges of this project?
iii. Which professionals need to be involved in the project from inception to implementation?
iv. Propose a framework that will guide decision-makers in assessing the appropriateness and sustainability of
greywater recycling within urban communities in South Africa based on the 2 pilot greywater units.

7.3.2. Awareness and education at UJ

i. The 1st awareness meeting was held with residents of Unit 51A on Tuesday, 22nd
September 2009 (Figure 25). The aim of the meeting was to determine residents’
perceptions (using the 1st questionnaire) towards the installation of the greywater
reuse system for toilet flushing in their unit, and introduce to the residents the
proposed project and the project team. The meeting was advertised using
posters placed at strategic spaces within the unit and invitation notes under
residents’ doors. The meeting started with the administration of the 1st
questionnaires. This was done in order to garner the perceptions of respondents
prior to any awareness was carried out. In this form, the initial perceptions of
respondents were not tainted by the information subsequently presented. This
was the typical format of all the meetings where the questionnaires were
administered.

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Figure 25. (Left) Some residents from Unit 51A and the residents association;
(Right) Some members of the project team responding to questions.

ii. The 2nd stakeholder meeting took place on the 18th of March 2010. Seven of the
16 female residents of Unit 51A were present at this meeting. Some of the
residents present were not resident in the unit in 2009 when the 1st meeting was
held and hence needing to be informed of the project;
rd
iii. The 3 stakeholder meeting took place on the 25th of March 2010. This meeting
was held with relevant personnel of the UJ maintenance department to acquaint
them with the plans and progress on the project;
iv. Similar to WITS, size A3, A4 and A5 posters were put up within the unit (see

Figure 24);
v. The 4th meeting with residents took place on the 5th of August 2010. This meeting
took place immediately after implementation of the greywater system and thus
provided residents with an opportunity to learn about the system, air their
concerns, and receive responses to certain questions. The concerns raised were
recorded and addressed subsequently. Some of these concerns and responses
are listed below:
 Residents’ concern: the often back flow of bath and shower greywater into the
ground floor bath and shower when released from the 1st floor. Project team
response: the plumbing was subsequently modified to separate the ground
and 1st floor greywater collection pipes;
 Residents’ concern: unpleasant smells from the greywater during flushing at
the beginning of the semester. Project team response: Due to the 6 week
inter-semester break when the residents were on holiday, the greywater in the

133
 tank had gone septic. The project team had omitted to undertake the regular
maintenance on the system prior to residents returning to the unit and hence
the unpleasant odours in the greywater during flushing after residents return
to the unit. Subsequent to this meeting, diversion pipes were introduced into
the system to prevent greywater storage during periods when the system was
not being used;
 Residents’ concern: the effect of the greywater on feminine hygiene especially
if there is a splash of greywater on the skin during toilet use. Project team
response: the project team were not aware of any negative impacts on dermal
or related health if splashes of greywater occurred during toilet use. However,
ingestion of the greywater, if contaminated with pathogenic microorganisms,
could compromise health. Respondents were therefore advised to observe
hygiene practices when using the toilets that flush with greywater similar to
what would typically happen when they use toilets that flush with municipal
water;
 Residents’ concern: the ring of scum often seen in the greywater toilet bowl.
Project team response; the ring of scum was often a result of either limited
use of the greywater toilets and hence, the deposition of scum around the
surface of the greywater within the toilet bowl or the lack of regular
maintenance. The project team committed to undertake maintenance twice a
week and encourage residents to use the greywater toilet as often as
possible.
 Residents’ concern: Low flushing pressure in the ground floor greywater toilet.
Project team response: This may be a result of a blockage in the pipe
supplying the toilet bowl and will be checked.

th
vi. The 5 meeting was held on the 28th of October 2010 and provided the project
team with the opportunity to field questions and thank the residents for their
cooperation on the project throughout the year.

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Figure 26. Fifth awareness meeting between Unit 51A residents and the project
team

7.4. Highlights of the perception surveys, awareness and education

i. Overall, a very high percentage of all respondents affirmed that the concept of
greywater reuse will be beneficial to the environment. Respondents therefore
overwhelmingly disagreed with the statement that treated greywater for
toilet/urinal flushing was disgusting;
ii. In comparison to garden watering, most respondents preferred toilet flushing;
iii. There was a higher percentage of comfort amongst respondents with installing a

greywater reuse system for toilet flushing at a non-residential building than at a

residential building. Consequently, those living in university residence were more
concerned about greywater reuse;
iv. The 15-21 yrs (undergraduate cohort) were generally more comfortable about

greywater reuse than the same percentage of the cohort of 22 yrs and older or
postgraduate students, academic and support staff. Consequently, the concern
expressed by the former was generally less than that for the latter;
v. Concern about getting sick from greywater reuse for toilet flushing was high at all
institutions. This highlighted the need to ensure that the implemented greywater
reuse systems were consistently safe and hygienic. The incidents regarding
greywater back flow into the ground floor bath tub and shower at UJ, unpleasant

135
 odours from the greywater during flushing, scum in the greywater, and concern
for dermal and related health resulted in increased concern about greywater
reuse;
vi. A significant percentage of responses prior to, immediately after and 3 months

after implementation depicted respondents confidence that the relevant

authorities will ensure that greywater is safe;
vii. The overall significant increases in the percentages of respondents satisfied with

the reduction in unpleasant smells and improvement in colour positively

influenced the average number of times respondents subsequently used the
greywater reuse toilets;
viii. The awareness sessions undertaken after administration of the perception survey

questionnaires ensured that the perceptions collected were not tainted by the
information or assurances provided by the project team and were thus, a true
reflection;
ix. In addition to the above point, the awareness sessions which were undertaken

earlier in the project, provided the project team with the opportunity to determine
or confirm the different areas of concern (e.g. unpleasant odour, greywater
colour, and concern for health) utmost in the minds of the respondents. These
areas of concern were therefore included in the subsequent questionnaires and
thus monitored over time;
x. An overall assessment of the greywater system is presented in Table 37. A larger
proportion of surveyed respondents at WITS (78 of the 90 respondents) and UJ
(9 of the 15 respondents) passed the system. However, it can be seen that likely
due to the negative experiences at UJ, 6 of the 15 respondents were neutral.

Table 37. Respondents’ overall assessment of the greywater reuse system

Scale About 7 months after implementation of the greywater system
WITS – 2010 UJ – 2010
Pass (No.) 78 9
Neutral (No.) 11 6
Fail (No.) 1 0
Total (No.) 90 15

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 8. TECHNICAL AND ECONOMIC ANALYSES REGARDING THE PILOT
GREYWATER REUSE SYSTEMS FOR TOILET FLUSHING

8.1. Logging of water consumption

The logging of toilet flushing and bulk potable water consumption at WITS and UJ
was aimed at determining the potable water savings (and consequently costs) at
both institutions as a result of greywater reuse for toilet flushing. A summary of the
methodologies employed and some of the results of this exercise are presented
below.

8.1.1. Logging of water consumption at WITS

Data on toilet flushing at WITS were collected from the 21st of May 2009. Initially, this
data was generated using manual counters which were installed in each toilet cistern
(Figure 27). Each time a toilet was flushed, the lever connected to the counter was
activated, causing the counter to record a digit. The number of digits registered by
the counter during a specified period indicated the number of times the toilet was
flushed. Due to moisture within the cisterns, several of the counters repeatedly
malfunctioned and thus, this method of measuring flushes had to be abandoned.
Electronic data loggers were subsequently installed in each toilet in October 2009 to
replace the manual counters.

The electronic data loggers employed (Figure 27), typically measure and store up to
32,510 voltage readings over a 0-30V d.c. measurement range. The user can easily
set up the logging rate and start time, and download the stored data by plugging the
data logger into a PC’s USB port and running the purpose designed software under
Windows 2000, XP and Vista (32-bit). The data can then be graphed, printed and
exported to other applications. The data logger is supplied with a lithium battery.
Correct functioning of the unit is indicated by flashing red and green LEDs. The data
logger features a pair of screw terminals and a set of measurement leads terminating
in crocodile clips

137
Figure 27. (Top left) A toilet cistern housing a manual counter with a lever;
(Top right) An electronic data logger; (Bottom left) A probe from an electronic
logger which measures voltage difference within water in the toilet cistern;
(Bottom right) Downloading data from an electronic logger unto a computer.

An implication of the change in loggers was the incompatibility between the data
generated using the manual counters (which were read every 3 hours between
06h00-18h00 and every 6 hours between 18h00 to 06h00) and the electronic loggers
(which logged flushing approximately every minute).

Table 38 shows the measured toilet flushing consumption within WITS prior to and
after implementation of the greywater reuse system. Due to the difficulty in
synchronising the data collected by the manual and electronic loggers, and the
limited data available on same months of multiple years, it was only possible to
compare the average toilet flushing consumption data for November 2009 and
November 2010 – these are the only months during the period of logging in which
electronic loggers were used and which present data for the before and after
greywater system implementation scenarios. These months are predominantly

138
examination periods where students are sparsely present and therefore, are not
reflective of teaching periods which would be considered peak periods for toilet
flushing.

Table 38. Potable water savings due to greywater reuse for flushing in 2 toilets
at WITS
Equipment

Month

(litres)
consumption
flushing
Monthly toilet
No of days logged

per day (litres)

for toilet flushing
water consumption
Average potable
No of toilets logged

2 toilets (litres)
greywater reuse in
day due to
potable water per
average savings in
mode of logging,
and using the same
For similar months

Comment
May-
09 10,098.00 11 918 12
Jun-09 25,227.00 30 841 12
Manual
Jul-09 37,134.00 31 1198 12
counters
Aug-09 39,366.00 31 1270 12
Sep-09 39,105.00 30 1304 12
Oct-09 25,452.00 31 821 12
Nov-09 18,162.00 30 605 12
Dec-09 6,804.00 31 219 12
Greywater system
Mar-10 14,301.00 22 650 10 implemented
Apr-10 16,389.00 30 546 10
May-
Electronic 10 10,881.00 31 351 10
loggers Jun-10 6,615.00 30 221 10
Jul-10 12,267.00 31 396 10
Aug-10 11,403.00 31 368 10
Sep-10 12,276.00 30 409 10
Oct-10 12,555.00 31 405 10
Nov 2009 minus Nov
Nov-10 7,695.00 20 385 10 220 2010

Based on the data for November 2009 and November 2010, the potable water
savings due to greywater reuse in 2 of the 12 toilets within WITS amounted to 220
litres per day. Assuming a peak factor of 2 (to represent demand during peak
periods), the potable water savings due to greywater reuse in 2 of the 12 toilets
would amount to about 440 litres per day. Other results to proceed from the data
generated at WITS include:
 There was on average, a bulk potable water savings of about 6% within the
building during off-peak teaching periods due to the greywater reuse system for
toilet flushing in 2 of the 12 toilets;

139
 There was on average, a bulk potable water savings of about 10% within the
building during peak teaching periods due to the greywater reuse system for toilet
flushing in 2 of the 12 toilets.

8.1.2. Logging of water consumption at UJ

At UJ, data on toilet flushing was metered using the electronic data loggers
described in section 8.1.1. There were however several problems with the loggers
often resulting in unreliable data. Table 39 shows toilet flushing consumption within
Unit 51A for 2 months of 2009 and 7 months of 2010 – periods when generated data
were considered reliable.

Table 39. Potable water savings due to greywater reuse for flushing in 2 toilets
at Unit 51A, Student Town, UJ
Mode of logging

Month

(litres)
consumption
flushing
Monthly toilet
No of days logged

per day (litres)

for toilet flushing
water consumption
Average potable
No of toilets logged

2 toilets (litres)
greywater reuse in
day due to
potable water per
average savings in
mode of logging,
and using the same
For similar months

Comment

Aug-09 6678 22 607.09 4

Sep-09 6210 21 591.43 4
Mar-10 3780 15 252.00 4
Apr-10 4725 30 157.50 4
May-10 7704 28 275.14 4
Greywater system
Electronic Jun-10 1809 13 139.15 2 installed
Jul-10 9810 22 445.91 2
August 2009 minus
Aug-10 16821 28 600.75 2 6.34 August 2010
September 2009
minus September
Sep-10 6786 15 452.40 2 139.03 2010

Based on the data presented, and calculation of potable water savings which were
only possible by comparing August and September 2009 (prior to greywater
implementation) with August and September 2010 (after greywater implementation),
the maximum potable water savings due to greywater reuse in 2 of the 4 toilets
amounted to 139 litres per day. Applying a peak factor of 2 (to represent demand
during peak periods – see below), the potable water savings due to greywater reuse

140
in 2 of the 12 toilets would amount to 278 litres per day. Other results to proceed
from the data generated at UJ include:
 Average number of flushes per resident per day was 3.89;
 the instantaneous peak factor calculated for toilet flushes was 1.98. This implies
that on average, the number of times the toilet is flushed during peak periods is
approximately twice the average number of flushes per resident;
 Over an 83 day period of measurement (11 June 2010 to 01 October 2010), total
toilet flushing consumption within the unit comprised 25% greywater and 75%
municipal potable water supply;
 Typical weekday (Monday to Thursday) and weekend (Saturday) toilet flushing
trends are depicted in Figure 28;
 The fact that there is 1 clear peak and a relatively constant demand thereafter
throughout the weekday may be favourable for the operation of the greywater
system as treated greywater would be continually used through most of the
day and not retained in the tank for long periods of time;
 Three distinct peaks are noticed for Saturday. The first peak is due to the use
of the toilets in the morning when residents wake up, albeit one hour later
(07h00) than during weekdays. The residents who remain in the unit most of
the day, have their lunch and supper approximately between 12h00-15h00
and 17h00-19h00 and therefore use the toilets at the times when the second
and third peaks occur.

141
 0.35
0.30
Flushes/hour/person

0.25
0.20
0.15
0.10
0.05
0.00
0:00:00
1:00:00
2:00:00
3:00:00
4:00:00
5:00:00
6:00:00
7:00:00
8:00:00
9:00:00
10:00:00
11:00:00
12:00:00
13:00:00
14:00:00
15:00:00
16:00:00
17:00:00
18:00:00
19:00:00
20:00:00
21:00:00
22:00:00
23:00:00
0.40
0.35
Flushes/hour/person

0.30
0.25
0.20
0.15
0.10
0.05
0.00
0:00:00
1:00:00
2:00:00
3:00:00
4:00:00
5:00:00
6:00:00
7:00:00
8:00:00
9:00:00
10:00:00
11:00:00
12:00:00
13:00:00
14:00:00
15:00:00
16:00:00
17:00:00
18:00:00
19:00:00
20:00:00
21:00:00
22:00:00
23:00:00
Figure 28. Flushing trends for a typical Monday-Thursday (Top) and Saturday
(Bottom) at UJ

8.2. Maintenance of the greywater systems at WITS and UJ

Maintenance tasks on the greywater systems typically required between 30-60

minutes at each instance – the lower limit during routine maintenance and the upper
limit during major maintenance. Maintenance was recommended weekly at WITS
and twice a week at UJ in order to guarantee optimal performance and typically
involved:
i. cleaning the sieves which would likely have trapped substances (hair or other
material) from the influent greywater;
ii. brushing down the scum which would have collected on the tank walls and on the
surface of the greywater in the tank;

142
iii. inspecting the chlorine capsules to remove any trapped sediments and to ensure

there are adequate chlorine tablets for disinfection;

iv. Inserting a cistern block in the sieves (and in the tank once in a while) to dye the

disinfected greywater;
v. Using a toilet brush to remove scum within the toilet bowl; and
vi. Recording of metered electricity (for the greywater pumps) and water readings

(for the toilet flushes, bulk municipal supply and rainwater tank at UJ).

8.3. Pros and cons of the pilot greywater reuse systems

A list of the pros and cons of the low-technology, low-cost greywater reuse systems,
as indicated by the beneficiaries, is presented below. Several of the points listed
below have been mentioned in Section 6.2. and Chapter 7. As a result of some of
the failures below, the initial pilot system (Figure 16) was modified as detailed in
section 6.2.1.

8.3.1. Pros
i. the systems were easily modifiable to suit site conditions;
ii. the systems required no specialised skill to conduct weekly maintenance which
required on average 30 minutes, and typically involved cleaning the sieves,
brushing down the scum within the tank, inspecting the chlorine capsules,
inserting a cistern block in the sieves, cleaning out scum in the toilet bowl and
recording metered readings for electricity and water;

8.3.2. Cons
i. The greywater system, which only performed sieving and disinfection, did not
remove the scum in the greywater and this resulted in visually unpleasing
greywater in the toilet bowl. The scum typically developed an unsightly ring above
the greywater level within the toilet bowl and this was particularly of concern at
UJ where the greywater was more turbid due to soaps, shampoos, detergents,
etc. than at WITS;
ii. When greywater was retained in the tanks for more than 48 hours, as was often
the case at UJ during term breaks/holidays , and/or when the chlorine tablets

143
 were not regularly replenished, the greywater became septic and produced
unpleasant smells during flushing;
iii. Due to an erroneous greywater pipe connection at UJ after installation, greywater

from the 1st floor bath and shower flowed into the ground floor bath and shower
and was a major concern and discomfort for the residents of the ground floor
especially during ablution;
iv. Preliminary microbiological tests of the greywater were conducted after the initial

greywater system was implemented. At the time, disinfection involved placing

bromine based tablets in the sieves once a week. These tests showed high
microbiological. As a result, the initial greywater system was modified to include 2
inline chlorinators which provided increased disinfection and reduced the
microbiological counts;
v. In order to ensure the retention time of greywater in the tanks was kept to about
24 hours, the volume of the tanks were deliberately kept small (~200 litres). At
WITS during peak (teaching) periods when the frequency of toilet flushing was
high, the greywater tanks often emptied out. As a result, the back-up municipal
potable water supply, which was only to be rarely used, kicked in. The regular
use of municipal supply negated some of the savings which were to be achieved
by implementing the greywater system;

8.4. Economic analysis of the pilot greywater reuse systems

In relation to economics, the case studies reviewed specified that long pay-back
periods tended to infer non-profitability, and thus tended to dampen potential and
actual users’ and decision-makers’ interests in greywater reuse. In these case
studies, greywater systems had a payback period of between 8-14 years (Sayers,
1998; Surendran and Wheatley, 1998; March et al., 2004; and Ghisi and Ferreira,
2007) with preference for between 2-4 years amongst potential respondents in
Melbourne, Australia (Christova-Boal et al., 1996). Payback period was therefore the
factor computed in the economic analysis of the pilot greywater reuse systems.

Costs considered over the systems 20 year design life included:

i. capital costs related to:

144
  purchasing the greywater treatment unit;
 installing/retrofitting the greywater treatment unit (which includes piping,
plumbing and workmanship);
ii. energy costs related to:
 operating the pumps;
 adding colour to the greywater;
 disinfecting the greywater;
 maintenance;

Assumptions made while computing payback periods from the year 2009 included:
 The design life of the greywater system is 20 years;
 The pumps will be replaced at the end of 10 years;
 Potable water prices will increase at an annual rate of 10% over the 20 year
period;
 Sewage prices will increase at the rate of 8% per annum over the 20 year
period;
 Electricity tariffs will increase at an annual rate 30% from 2010 to 2012 and
thereafter 10%;
 Price of cistern blocks will increase at an annual rate of 5%;
 The service agreement is a once-off cost for 12 months after installation of
greywater system;
 Sewage from a building is estimated to be about 55% of the bulk potable
water supply;
 Due to the nature of business occurring in the different buildings, it is
expected that the WITS building would effectively be open and hence
greywater system functional, for 330 days (90%) of the year while greywater
system at UJ effectively functional for 200 days (55%) of the year.

8.4.1. Payback period computation at WITS

Table 40 presents capital and recurrent costs of the greywater reuse system, Table
41 presents potable and sewage savings due to greywater reuse in the 2 toilets, and
Table 42 presents cumulative cash flows and hence, payback period for the

145
greywater reuse system.

1
Purchase and installation of the greywater reuse system:
 1 No. 200 litre greywater tank
 pipes and appurtenances
 pipe filter and 2 No. 2 mm sieves
 wall supports and braces
 retrofitting of 2 toilets while retaining the previous function
 1 No. 9 metre head pump and 1 No. 14 m head pump*
 workmanship, excavation, drilling of basement cores and equipment
 1st year service agreement
 2 chlorinators
 1 No. 75 litre municipal water back-up tank
2
Electricity consumption = approximately 2 KW.hr per month (1 KW.hr ~ R0.50) with
a monthly surcharge and 14% VAT of ~ R2.00 = ~R3 per month;
3
Chlorine = 80 tablets per annum at ~ R10 per tablet;
4
Cistern blocks = 45 blocks per annum at ~R8 per week;
6
Pump replacement: assume both pumps are replaced at the end of 10 years at
present value of R4,000.00

146
 2028
0 363 2,022 910 0 0 3,295

2027
0 330 1,925 866 0 0 3,122

2026
0 300 1,834 825 0 0 2,959

2025
0 273 1,746 786 0 0 2,805

2024
0 248 1,663 748 0 0 2,660

2023 0 226 1,584 713 0 0 2,522

2022 0 205 1,509 679 0 0 2,392

2021
0 186 1,437 647 0 0 2,270

2020
0 170 1,368 616 0 0 2,154

2019
0 154 1,303 586 0 7,787 9,831

2018
0 140 1,241 558 0 0 1,940

2017
0 127 1,182 532 0 0 1,841

147
2016
0 116 1,126 507 0 0 1,748

2015
0 105 1,072 482 0 0 1,660

2014
0 96 1,021 459 0 0 1,576

2013
0 87 972 438 0 0 1,497
Table 40. Capital and recurrent costs at WITS

2012
0 79 926 417 0 0 1,422

2011
0 61 882 397 0 0 1,340

2010
0 47 840 378 0 0 1,265

2009
38,045 36 800 360 0 0 39,241
Year

Service agreement (R)5

Replacement of pumps
Electricity consumption
Cost of the greywater

Chlorine tablets (R)3

Cistern blocks (R)4

treatment unit (R)1

Total (R)
(R)2

(R)6
Table 41. Savings at WITS

2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028

Year
Daily savings in
potable water
(litres) due to
Economic greywater reuse in

440
benefit 2 toilets
(i.e. Annual savings in
annual potable water (kilo
average litres) (x 330 days)

1,45.20
savings
in potable Annual savings (R)
water) in potable water at
R10.58 per kilolitre
(2009 tariff)

1,536.22
1,689.84
1,858.82
2,044.70
2,249.17
2,474.09
2,721.50
2,993.65
3,293.02
3,622.32
3,984.55
4,383.00
4,821.30
5,303.43
5,833.78
6,417.16
7,058.87
7,764.76
8,541.23
9,395.36

Daily savings in
sewage (litres) due
Environm to greywater reuse
ental in 2 toilets (55% of
benefit potable water

242.00
(i.e. savings)
reduced Annual savings in
sewage sewage (kilo litres)
treatment due to greywater
costs due reuse in 2 toilets (x

79.86
to 330 days)
reduced Annual savings in
return sewage at R7.00
flows) per KL (2009 tariff)

559.02
603.74
652.04
704.20
760.54
821.38
887.09
958.06
1,034.71
1,117.48
1,206.88
1,303.43
1,407.71
1,520.32
1,641.95
1,773.31
1,915.17
2,068.38
2,233.85
2,412.56

148
 2028 3,294.69 11,807.92 8,513.23 26,029.72

2027 3,122.07 10,775.09 7,653.02 17,516.48

2026 2,959.09 9,833.14 6,874.05 9,863.46

2025 2,805.18 8,974.04 6,168.86 2,989.41

2024 2,659.78 8,190.46 5,530.68 -3,179.45

2023 2,522.38 7,475.73 4,953.35 -8,710.13

2022 2,392.50 6,823.76 4,431.26 -13,663.48

2021 2,269.69 6,229.01 3,959.32 -18,094.74

2020 2,153.53 5,686.44 3,532.90 -22,054.06

2019 9,830.65 5,191.43 -4,639.21 -25,586.96

2018 1,939.66 4,739.80 2,800.14 -20,947.75

149
2017 1,841.23 4,327.72 2,486.50 -23,747.89

2016 1,748.04 3,951.71 2,203.68 -26,234.39

2015 1,659.78 3,608.59 1,948.81 -28,438.07

2014 1,576.19 3,295.48 1,719.29 -30,386.88

2013 1,496.99 3,009.71 1,512.73 -32,106.17

Table 42. Cumulative cash flow at WITS

2012 1,421.94 2,748.91 1,326.97 -33,618.89

2011 1,339.74 2,510.86 1,171.12 -34,945.86

2010 1,264.80 2,293.58 1,028.78 -36,116.98

2009 39,241.00 2,095.24 -37,145.76 -37,145.76

Year

Outflow (capital

Inflow (potable

cash flow (R )
Net cash flow
savings (R )
+ recurrent)

Cumulative
costs (R)

sewage)
water +

(R )
8.4.2. Payback period computation at UJ

Table 43 presents capital and recurrent costs of the greywater reuse system at UJ,
Table 44 presents potable and sewage savings due to greywater reuse in the 2
toilets, and Table 45 presents cumulative cash flows and hence, payback period for
the greywater reuse system.

1
Purchase and installation of the greywater reuse system:
 1 No. 200 litre greywater tank
 pipes and appurtenances
 pipe filter and 2 No. 2 mm sieves
 wall supports and braces
 retrofitting of 2 toilets while retaining the previous function
 1 No. 6 metre head pump and 1 No. 9 m head pump*
 workmanship, excavation and equipment
 2 chlorinators
2
Electricity consumption = approximately 2 KW.hr per month (1 KW.hr ~ R0.50) with
a monthly surcharge and 14% VAT of ~ R2.00 = ~R3 per month;
3
Chlorine = 80 tablets per annum at ~ R10 per tablet;
4
Cistern blocks = 45 blocks per annum at ~R8 per week;
5
Service agreement for the 1st year;
6
Pump replacement: assume both pumps are replaced at the end of 10 years at
present value of R4,000.00;
7
A 2.5 kl rainwater tank, piping and diversion system.

150
 2028
0 363 2,022 910 0 0 0 3,295

2027
0 330 1,925 866 0 0 0 3,122

2026
0 300 1,834 825 0 0 0 2,959

2025
0 273 1,746 786 0 0 0 2,805

2024
0 248 1,663 748 0 0 0 2,660

2023 0 226 1,584 713 0 0 0 2,522

2022 0 205 1,509 679 0 0 0 2,392

2021
0 186 1,437 647 0 0 0 2,270

2020
0 170 1,368 616 0 0 0 2,154

2019
0 154 1,303 586 0 7,787 0 9,831

2018
0 140 1,241 558 0 0 0 1,940

2017
0 127 1,182 532 0 0 0 1,841

151
2016
0 116 1,126 507 0 0 0 1,748

2015
0 105 1,072 482 0 0 0 1,660

2014
0 96 1,021 459 0 0 0 1,576

2013
0 87 972 438 0 0 0 1,497
Table 43. Capital and recurrent costs at UJ

2012
0 79 926 417 0 0 0 1,422

2011
0 61 882 397 0 0 0 1,340

2010
0 47 840 378 0 0 0 1,265

2009
38,200 36 800 360 7,200 0 9,300 55,896
Year

Service agreement (R)5

Replacement of pumps
Electricity consumption

harvesting system (R)7

Cost of the greywater

Cost of the rainwater

Chlorine tablets (R)3

Cistern blocks (R)4

treatment unit (R)1

Total (R)
(R)2

(R)6
Table 44. Savings at UJ

2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028

Year
Daily savings in
potable water
(litres) due to
Economic greywater reuse in

278
(i.e. 2 toilets
annual Annual savings in
average potable water (kilo
litres) (x 200 days)

55.60
savings
in potable Annual savings (R)
water) in potable water at
R10.58 per kilolitre
(2009 tariff)

588.25
647.07
711.78
782.96
861.25
947.38
1,042.12
1,146.33
1,260.96
1,387.06
1,525.76
1,678.34
1,846.17
2,030.79
2,233.87
2,457.26
2,702.98
2,973.28
3,270.61
3,597.67

Daily savings in
sewage (litres) due
to greywater reuse
Environm in 2 toilets (55% of
ental (i.e. potable water

152.90
reduced savings)
sewage Annual savings in
treatment sewage (kilo litres)
costs due due to greywater
to reuse in 2 toilets (x

30.58
reduced 200 days
return Annual savings in
flows) sewage at R7.00
per KL (2009 tariff)

214.06
231.18
249.68
269.65
291.23
314.52
339.69
366.86
396.21
427.91
462.14
499.11
539.04
582.16
628.74
679.03
733.36
792.03
855.39
923.82

152
 2028
3,294.69 4,521.49 1,226.80 -60,706.20

2027
3,122.07 4,126.00 1,003.93 -61,933.00

2026
2,959.09 3,765.31 806.21 -62,936.93

2025
2,805.18 3,436.34 631.16 -63,743.15

2024
2,659.78 3,136.29 476.51 -64,374.31

2023
2,522.38 2,862.61 340.23 -64,850.82

2022
2,392.50 2,612.95 220.46 -65,191.05

2021
2,269.69 2,385.21 115.53 -65,411.50

2020
2,153.53 2,177.45 23.92 -65,527.03

2019
9,830.65 1,987.90 -7,842.74 -65,550.95

2018
1,939.66 1,814.96 -124.69 -57,708.20

153
2017
1,841.23 1,657.17 -184.05 -57,583.51

2016
1,748.04 1,513.19 -234.84 -57,399.46

2015
1,659.78 1,381.80 -277.98 -57,164.61

2014
1,576.19 1,261.90 -314.28 -56,886.63

2013
1,496.99 1,152.48 -344.51 -56,572.35
Table 45. Cumulative cash flow at UJ

2012
1,421.94 1,052.61 -369.32 -56,227.84

2011
1,339.74 961.46 -378.28 -55,858.51

2010
1,264.80 878.26 -386.54 -55,480.23

2009
55,896.00 802.31 -55,093.69 -55,093.69
Year

Outflow (capital

Inflow (potable

cash flow (R )
Net cash flow
savings (R )
+ recurrent)

Cumulative
costs (R)

sewage)
water +

(R )
From Table 42, the payback period at WITS was achieved 17 years after
implementation while at UJ (Table 45) payback could not be achieved within the 20
year design life for the infrastructure. The payback at WITS (which was within the 20
year design life of the infrastructure) resulted from larger savings in both potable
water and sewage treatment due to greywater reuse for flushing 2 toilets, and the
lower initial cost of the greywater system in comparison to UJ. Therefore, on the
basis of users paying the full costs of the reuse systems and a preferred payback
period of 8 years, the systems at WITS and UJ were economically unviable.

In many of the communities where payback has been within the preferred durations,
governments have been known to provide subsidies, e.g. 50% of capital costs in
Cyprus (Kambanellas, 2007) and about 50% of capital costs in Japan (Chung and
White, 2010). Hence, in order to achieve a payback period of 8 years for the reuse
systems, the 2009 capital costs at WITS will have to reduce to about 30% of its 2009
value (Table 46). At UJ however, an 8 year payback could only be realised when
users paid only 76.5% of the recurrent costs. This means that in order to obtain a
payback period of 8 years at UJ, initial (2009) capital costs, the cost for replacing 2
pumps at the end of 10 years, and 23.5% of the recurrent costs will not be borne by
the user (Table 47).

154
 2028
3,294.69 11,807.92 8,513.23 52,661.22

2027
3,122.07 10,775.09 7,653.02 44,147.98

2026
2,959.09 9,833.14 6,874.05 36,494.96

2025
2,805.18 8,974.04 6,168.86 29,620.91

2024
2,659.78 8,190.46 5,530.68 23,452.05

2023
2,522.38 7,475.73 4,953.35 17,921.37

2022
2,392.50 6,823.76 4,431.26 12,968.02

2021
2,269.69 6,229.01 3,959.32 8,536.76
Table 46. Cumulative cash flow at WITS with capital costs at 30% of initial value

2020
2,153.53 5,686.44 3,532.90 4,577.44

2019
9,830.65 5,191.43 -4,639.21 1,044.54

2018
1,939.66 4,739.80 2,800.14 5,683.75

155
2017
1,841.23 4,327.72 2,486.50 2,883.61

2016
1,748.04 3,951.71 2,203.68 397.11

2015
1,659.78 3,608.59 1,948.81 -1,806.57

2014
1,576.19 3,295.48 1,719.29 -3,755.38

2013
1,496.99 3,009.71 1,512.73 -5,474.67

2012
1,421.94 2,748.91 1,326.97 -6,987.39

2011
1,339.74 2,510.86 1,171.12 -8,314.36

2010
1,264.80 2,293.58 1,028.78 -9,485.48

2009
12,609.50 2,095.24 -10,514.26 -10,514.26
Year

Outflow (capital

Inflow (potable

cash flow (R )
Net cash flow
savings (R )
+ recurrent)

Cumulative
costs (R)

sewage)
water +

(R )
 2028 2,520.44 4,521.49 2,001.05 11,581.93

2027 2,388.38 4,126.00 1,737.62 9,580.87

2026 2,263.71 3,765.31 1,501.60 7,843.25

Table 47. Cumulative cash flow at UJ with users only paying 76.5% of present value of 2009 recurrent costs

2025 2,145.96 3,436.34 1,290.38 6,341.65

2024 2,034.73 3,136.29 1,101.56 5,051.27

2023 1,929.62 2,862.61 932.99 3,949.71

2022 1,830.26 2,612.95 782.69 3,016.73

2021 1,736.31 2,385.21 648.90 2,234.03

2020 1,647.45 2,177.45 530.00 1,585.13

2019 1,563.39 1,987.90 424.51 1,055.13

2018 1,483.84 1,814.96 331.13 630.62

156
2017 1,408.54 1,657.17 248.63 299.49

2016 1,337.25 1,513.19 175.94 50.86

2015 1,269.73 1,381.80 112.07 -125.08

2014 1,205.78 1,261.90 56.12 -237.15

2013 1,145.20 1,152.48 7.28 -293.27

2012 1,087.78 1,052.61 -35.17 -300.56

2011 1,024.90 961.46 -63.44 -265.39

2010 967.57 878.26 -89.31 -201.95

2009 914.94 802.31 -112.63 -112.63

Year

Outflow (capital

Inflow (potable

cash flow (R )
Net cash flow
savings (R )
+ recurrent)

Cumulative
costs (R)

sewage)
water +

(R )
 9. SUMMARY OF FINDINGS, RECOMMENDATIONS AND CONCLUSION

The question that drove the need for a South African investigation into the reuse of
greywater for toilet flushing was:

“Given the increasing scarcity of high quality water resources in many South African
communities and the need for sustainable supplemental water resources for large
quantity but lower quality water requirements (e.g. toilet flushing), how viable are
greywater reuse systems for toilet flushing in high density urban buildings?”

In response to this question, several objectives were framed within context of the
triple bottom line attributes of sustainability, i.e.:
i. To review knowledge and experience in greywater reuse and reuse systems
specifically for toilet flushing;
ii. To interrogate regulations and guidelines pertaining to greywater reuse for toilet
flushing in South Africa and to propose a structure for a national guideline;
iii. To collate a database of locally available greywater reuse systems suitable for

toilet flushing and to develop a robust framework for evaluating these systems for
local implementation;
iv. To monitor perceptions of potential and actual beneficiaries towards the

implementation of greywater reuse systems primarily for toilet flushing;

v. To implement and monitor a pilot greywater reuse system for toilet flushing at 2
distinct water users, i.e. a residential and educational building; and
vi. To undertake an economical analysis of the pilot greywater reuse systems;

The above objectives were achieved through undertaking several tasks, i.e. a
detailed literature survey, which attempted to garner varied local and international
experiences regarding greywater reuse for toilet flushing; an extensive review of
regulations and guidelines pertaining to greywater reuse and the development of a
proposed structure for a national guideline; the development of a database of locally
available greywater reuse systems for toilet flushing and a framework to guide the
evaluation of the diverse systems or similar technologies; implementation of a pilot
greywater reuse system for toilet flushing in a non-residential (educational) and
residential (student residence) building, and monitoring certain parameters over time;
157
surveys of perceptions across potential and actual users of the implemented pilot
greywater reuse systems over time and awareness exercises; and an economical
analysis (using payback period) of the pilot systems.

The following sections summarise the findings of this project and recommendations
for the future. These sections are classified according to the social and economic
attributes of sustainability which helped to frame the objectives and tasks carried out
in this project.

9.1. Summary of findings and recommendations related to the social

(including regulatory) attribute

9.1.1. Summary of findings and recommendations relating to perceptions

i. Amongst the potential uses for greywater presented to respondents in this study
(i.e. toilet flushing and irrigation), toilet flushing was the preferred use. This was
due to the perception of possibly lesser contact with the greywater if used for
flushing than if used for irrigation. In essence, the further away the greywater was
to dermal contact or ingestion, the better for respondents. Reinforcing this
perception was the preference amongst respondents for the pilot systems to be
installed in non-residential (public) than residential (private) buildings. It was
therefore no surprise to see that the overall assessment of the pilot greywater
system after about 7 months of operation (Table 37) received a higher pass mark
from respondents at WITS (non-residential) (78 out of 90 = 87%) than at UJ
(residential) (9 out of 15=60%);
ii. Prior to the implementation of the pilot greywater reuse systems at the 2 sites,
most of the respondents surveyed affirmed that the concept of greywater reuse
for toilet flushing was a good idea that could benefit the environment (Table 33).
After implementation of the systems, and the problems and/or discomforts
experienced by the respondents (e.g. turbid/foamy greywater in the toilet bowls
often forming an unsightly ring, unpleasant odours during flushing during certain
times, and back flow of greywater from the 1st floor drain into the ground floor
bath tub and shower at UJ) there was increased concern about hygiene.

158
 Surprisingly, this did not negate the earlier affirmation about the concept of
greywater reuse, nor did it result in the reduced use of the greywater toilets
(Table 36). The pro-action of the project team in regularly allaying concerns
during the awareness sessions and speedily rectifying reported problems is
suspected to have played a significant role in sustaining positive perceptions
amongst respondents.

In essence therefore, a critical component that will sustain beneficiaries’

confidence in greywater reuse for toilet flushing (or similar interventions using
non-conventional water resources) and the effective functioning of these
systems, will be the pro-active and regular community engagement, awareness
and maintenance/repair interventions. At the onset of projects of this nature,
beneficiaries often need to be assured that the systems are not a threat to health,
are hygienic, and can be reliably operated and it is the responsibility of the
implementing authorities to guarantee this until such a time that beneficiaries are
confident to operate the systems themselves. In addition, based on the negative
user perceptions due to the unpleasant visual appearance of the greywater, it is
evident that greywater systems will need to include a final, polishing filter to
significantly reduce turbidity and remove scum from the greywater prior to use;
iii. With regards to demographics, respondents younger than 21 years were

generally more comfortable about greywater reuse than older respondents and
therefore should be targeted when considering greywater reuse for toilet flushing
(or similar non-conventional water resource use interventions);

9.1.2. Summary of findings and recommendations relating to regulations and

guidelines

From the review of regulations and guidelines conducted and the overview of
government’s broad position regarding greywater reuse for various uses, some key
issues worth noting are listed below:
i. In South Africa, there are no national regulations specifically addressing
greywater reuse and management. There are however some sections/clauses in
broad regulations (i.e. EAF, 1984; DWAF, 2001; DWAF, 2004a; and DWAF,

159
 2004c) and by-laws (CoCT, 2010; The Durban Metro, 2008; and The Moses
Kotane Local Municipality Water and Sanitation By-Laws, 2008) which address
greywater reuse and/or management, albeit to differing degrees of detail. In these
sections/clauses, there is no fundamental objection in principle to the use of
household greywater for toilet flushing, as long as nuisances, which compromise
public health and the pollution status of the environment, are avoided. In fact, in
most of the pronouncements made by national governments (Table 14), there is
encouragement to reuse greywater for flushing toilets. What is missing is the
absence of national regulations which has created a chasm between national
governments’ unequivocal encouragement for greywater reuse for toilet flushing
(and irrigation) and the actual implementation of greywater reuse and reuse
systems in provinces, municipalities, institutions and households;
ii. Developing a national regulation that specifically addresses greywater reuse and
management would require input from different departments, e.g. water services,
water supply, sanitation and water resource management;
iii. In addition to the lack of national regulations for greywater reuse and

management, is the lack of a definition for greywater as a separate wastewater

stream that is distinct from blackwater (Rodda et al., 2010). The implication of this
is that the understanding (and thus, legal position) of greywater is inconsistent
amongst the various municipal councils that have by-laws addressing greywater.
For example, the City of Cape Town guidelines (CoCT, 2005) define greywater
as “wastewater from the washing of laundry, personal bathing and cooking
activities” while the Moses Kotane Local Municipality Water and Sanitation By-
laws (2008) understands greywater to be domestic wastewater excluding “water
derived from any kitchen ….discharges”. A national definition, and thus shared
understanding of greywater is urgently needed;
iv. A consequence of the lack of national regulations is the lack of national

guidelines/plumbing codes specifically addressing greywater reuse in South

Africa. A nationally consistent approach to the management of health and
environmental risks from greywater reuse requires high-level national guidance
on risk assessment and management. These guidelines will not be mandatory
and will have no formal legal status. However, their adoption will provide a shared
national objective, and at the same time allow flexibility of response to different

160
 circumstances at regional and local levels (EPHC et al., 2006). The proposed
structure for a national guideline for greywater reuse for toilet flushing is
presented in Section 9.3. The proposed structure is based on the structure
proposed by Rodda et al. (2010) for small-scale agriculture and gardens, and
incorporates some of the recommendations of several guidelines that have been
developed in the past for greywater use and management in South Africa, e.g.
Wood et al., 2001; Murphy, 2006; and Carden et al., 2007.;

9.2. Summary of findings and recommendations relating to the economic

(including technical) attribute

9.2.1. Summary of findings and recommendations relating to technical criteria

Listed below are summaries of the findings and recommendations addressing

technical criteria which were involved in this study, i.e. the evaluation of greywater
systems; implementation, operation and maintenance of the pilot systems; and the
determination of municipal potable water savings due to greywater reuse for toilet
flushing.
i. It is imperative that prior to the selection of a package plant for greywater reuse, it
is evaluated alongside other plants using the proposed framework developed in
this study (or similar). This is because there exists a variety of package plants
which purport to treat greywater for toilet flushing but for which limited or no data
is available to verify the claims. Preferably, a physical evaluation of the plant and
its effluent should be carried out. If an independent institution (e.g. the South
African Bureau of Standards, SABS or the Joint Acceptance Scheme for Water
Services Installation Components, JASWIC) undertook the testing and
certification (or non-certification) of these plants, the evaluation and selection
process will be much more effective and implemented systems will function as
expected;
ii. As a result of the diverse range of locally available technologies employed for
greywater reuse, the quality of treated greywater, and consequently beneficiaries’
perceptions, is bound to vary. The technology selected for greywater reuse in this
study (i.e. low-technology and low-cost) determined the visual quality of sieved

161
 greywater (e.g. turbid/foamy greywater and unpleasant odours) and
consequently, influenced beneficiaries’ perceptions;
iii. The low-technology, low-cost greywater reuse system implemented (Section 6.2)

produced several pros and cons.

The pros were: (a) the systems were easy to modify to suit site conditions; and
(b) the systems required no specialised skill to conduct weekly maintenance
which required on average 30 minutes, and typically involved cleaning the sieves,
brushing down the scum within the tank, inspecting the chlorine capsules,
inserting a cistern block in the sieves, cleaning out scum in the toilet bowl and
recording metered readings for electricity and water;

The cons which had a major impact on beneficiaries’ perceptions were: (a) the
greywater system, which did not remove scum, produced visually unpleasing
(turbid/foamy) greywater especially at UJ and this was a particular concern in
terms of health and hygiene for beneficiaries. In effect, the quality of influent that
flowed into the system determined to a large extent the quality of effluent. To
overcome this, greywater systems will need to include a final, polishing filter to
significantly reduce turbidity from the greywater prior to use; (b) sieved greywater
retained in the tanks for more than 48 hours and/or depleted chlorine, resulted in
septic greywater which produced unpleasant smells during flushing; (c) an
erroneous pipe connection at UJ resulted in greywater from the 1st floor bath and
shower flowing into the ground floor bath and shower and this was a major cause
for concern and discomfort for residents; (d) preliminary microbiological tests of
the greywater produced by the initial implemented greywater system showed high
microbiological counts, and thus the system was modified to include 2 inline
chlorinators which provided increased disinfection; (e) the small volume of the
tank at WITS (~200 litres) in order to reduce the retention time of the greywater
often resulted in the tank emptying out during peak (teaching) periods when the
frequency of toilet flushing was high. As a result, the back-up municipal potable
water supply was often used, thus negating the potable water savings which were
to be achieved by implementing the greywater system;

162
iv. In order to avoid the difficulties and consequently, additional costs associated

with retrofitting greywater reuse systems for toilet flushing into existing buildings
not originally designed for these systems, it is preferable that reuse be
incorporated into the designs for new buildings. To achieve this, there will be
need to create awareness amongst decision-makers, builders, plumbers, product
manufacturers, architects, etc. to the potential of greywater reuse for toilet
flushing.
v. It was difficult to appreciate the municipal potable water savings due to greywater
reuse for toilet flushing due to the fact that only 2 out of 12 toilets (at WITS) and 2
out of 4 toilets (at UJ) were retrofitted for greywater flushing. However, At WITS,
there was on average, a bulk potable water savings of about 6% during off-peak
teaching periods and 10% during peak teaching periods due to greywater reuse
for toilet flushing in 2 of the 12 toilets. In volumetric terms, this amounted to an
average of about 440 litres per day during the academic term. At UJ, there was
on average, a 25% saving in total potable water used for toilet flushing during the
academic term. In volumetric terms, this amounted to an average of about 278
litres per day. From these results, WITS (non-residential), due to larger total
potable water volumes, achieved larger potable water savings (and consequently
costs) than UJ (residential);

9.2.2. Summary of findings and recommendations relating to the economic analysis

of the pilot greywater systems

i. From the analysis undertaken of the implemented greywater reuse systems, the
payback period at WITS was 17 years (Table 42) while at UJ (Table 45) payback
could not be realised within the 20 year design life for the infrastructure. The
payback at WITS (which was within the 20 year design life of the infrastructure)
resulted from larger savings in both potable water and sewage treatment due to
greywater reuse for flushing 2 toilets, and the lower initial cost of the greywater
system in comparison to UJ. Therefore, on the basis of users paying the full costs
of the reuse systems and a preferred payback period of 8 years, the systems at
WITS and UJ were economically unviable;

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ii. In many of the communities where payback has been within the preferred
durations (8-14 years), governments have been known to provide subsidies, e.g.
50% of capital costs in Cyprus (Kambanellas, 2007) and about 50% of capital
costs in Japan (Chung and White, 2010). Hence, in order to achieve a payback
period of 8 years for the reuse systems, the initial costs at WITS will have to
reduce to about 30% of its 2009 value (Table 46). At UJ however, an 8 year
payback will only be realised when users paid only 76.5% of the recurrent costs
(Table 47).

From the above, it is clear that the implemented pilot greywater reuse systems for
toilet flushing will not be economically viable in relation to payback period for
prospective beneficiaries unless (i) subsidies are applied; (ii) the costs of potable
water and/or sewage treatment increase substantially over time; (iii) there is a
larger proportion of flushing with greywater within each site resulting in increased
potable water and sewage treatment savings; and/or (iv) the initial costs of these
systems decrease due to market competition over time. This is especially
considering the fact that the pilot systems implemented in this study, which
comprised of low technology, were one of the lowest priced systems evaluated in
the framework.

9.3. Proposed structure of a national guideline for greywater reuse systems for
toilet flushing

Based on the key issues highlighted above, the following sub-sections present the
structure of a proposed guideline for greywater reuse for toilet flushing. This
structure is based on that presented by Rodda et al. (2010) (for consistency and
ease to amalgamate if considered in the future) but adapted to greywater reuse for
toilet flushing.

9.3.1. The intended users for this guideline will be:

i. Municipalities who wish to initiate, support, implement or regulate on-site

greywater reuse for toilet flushing;

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ii. Non-residential institutions who wish to initiate, support, implement or monitor on-
site greywater reuse for toilet flushing;
iii. Residential communities and individuals who wish to plan for (or implement)

greywater reuse systems for toilet flushing on their properties or in their

settlements, and need guidance in doing so.

9.3.2. The focus of the guidelines will be to:

i. Minimize the of risks of illness in users of toilets that flush with greywater;
ii. Minimize the of risks of illness which may occur in residents or users of a building
where greywater is reused for toilet flushing and where contamination of potable
water supplies has a probability of occurring due to a cross-connection; and
iii. Publicize best practice in the planning, implementation, use, operation,
monitoring and management of greywater systems for toilet flushing.

9.3.3. Major sources of information:

i. As indicated above, the major source of information employed in the

development of the structure of the guideline is the Water Research Commission
Report No 1639/1/10, titled “Sustainable use of greywater in small-scale
agriculture and gardens in South Africa” by Rodda et al., 2010) which
incorporates information and recommendations from Murphy (2006), Carden et
al. (2007), and WHO (2006);
ii. In addition to the above references, the proposed structure below incorporates
some information and recommendations from DWAF (2004a), The Official
Journal of the European Union (2005), Landcom’s WSUD strategy (2003),
(USEPA, 2007), and Surendran & Wheatley (1998);

9.3.4. The proposed elements of the guideline will be:

i. Managing risks and uncertainty in greywater reuse for toilet flushing;

ii. Greywater quality: guide to greywater constituents;
iii. Greywater quality: mitigation of greywater quality;

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iv. Collation of best practices regarding greywater reuse and plumbing.

Managing risks and uncertainty in greywater reuse for toilet flushing

Risks describe the probability of exposure to a hazard. In Rodda et al. (2010), 3
major risk management scenarios were identified, all relating to the extent of
characterisation of the greywater to be used for irrigation. In order of decreasing risk
and decreasing uncertainty, these were:
 Category 1: No analysis of greywater prior to use;
 Category 2: Minimum analysis of greywater prior to use (defined as pH, EC, SAR
and E. coli), and compliance with quality limits set on these; and
 Category 3: Full analysis of greywater prior to use (defined as minimum analysis
plus boron, COD, oil and grease, SS, total inorganic nitrogen and total
phosphorus), and compliance with quality limits set on these.

For greywater reuse for toilet flushing, similar risk management scenarios as above
could be applied. The basis for these scenarios would be the quality of greywater
that can be reused for toilet flushing in decreasing order of risk and uncertainty. This
categorization is important because decreasing order of risk and uncertainty is
typically related to higher technologies and therefore high costs and this is often not
realistic for on-site greywater reuse projects in buildings where reduction of cost is
critical. Hence, by permitting higher risk and uncertainty in greywater reuse for toilet
flushing (and thus lower costs) it will be necessary to prescribe certain levels of
analysis of the greywater to guarantee some level of hygiene and reduced risks to
health. Based on the constituents (identified in the next section) typically measured
for unrestricted urban reuse, a proposed categorization is:

 Category 1: No analysis of greywater prior to use.

 Category 2: Minimum analysis of greywater prior to use (defined as BOD5, TSS
or Turbidity, Total Coliform, Faecal Coliform, E. coli and chlorine residual), and
compliance with the quality limits set on these; and
 Category 3: Full analysis of greywater prior to use (defined as potable water
quality), and compliance with quality limits set on this quality of water.

166
In the review of regulations and guidelines presented on unrestricted urban reuse
(which incorporates toilet flushing), it is standard practice that greywater to be reused
for toilet flushing is regularly analysed and mitigated. Some basic handling rules that
mitigate risks when reusing greywater include (Murphy, 2006):
 Do not store greywater for more than 24 hours (and preferably no more than a
few hours) before use;
 Do not use greywater if anyone on the premises is suffering from an infectious
health condition; and
 Wash hands after contact with greywater.

Greywater quality: guide to greywater constituents

This sub-section is aimed at providing the quality criteria against which measured
greywater constituents are compared. As sample, the section below is specifically for
Category 2 (minimum analysis) listed in the sub-section above.

The constituents for inclusion in this section of the guidelines were identified from the
review of regulations and guidelines (USEPA and USAID, 2004; EPHC et al., 2006;
Surendran and Wheatley, 1998; etc.) carried out in Chapter 4 for greywater reuse for
unrestricted urban reuse (which includes toilet flushing). The table below shows the
greywater constituents that should be regularly measured and the average and or
maximum values or ranges against which greywater constituents may be measured.

Table 48. Greywater constituents typically measured for unrestricted urban

reuse (including toilet flushing)
Constituent Average Maximum
BOD5 (mg/l) 5 -10 20-30
TSS (mg/l) 5-10 20-30
Turbidity (NTU) 2 5
E. coli (cfu/100 ml) 0-10 200
Faecal coliform (cfu/100 ml) 0-10 23-200
Total coliform (cfu/100 ml) 2.2-10 23
Chlorine residual (mg/l) >0.5

This sub-section should also provide guidance on the greywater sampling frequency
and number of samples to be collected.

167
Greywater quality: mitigation of greywater quality
Greywater quality typically requires mitigation to make it suitable for use in toilet
flushing. Treatment may vary from primary treatment (e.g. sieving/filtering) to
advanced treatment (e.g. coagulation, sedimentation, membrane filtration and UV
disinfection) and there exists different treatment system configurations which have
been developed and that achieve different pollutant efficiencies. A review of these
technologies is presented in Chapter 5.

Collation of best practices regarding greywater reuse and plumbing.

This sub-section is intended at both minimising the risks of illness to users and
residents, and presenting best practice in the planning, implementation, use,
operation, monitoring and management of greywater systems for toilet flushing.
Some items proceeding from the experiences garnered in this study which relate to
plumbing best practice are listed below:
 Simple technological solutions should be explored for greywater reuse systems
for toilet flushing so that these systems can be easy to modify, operate and
maintain;
 Technological validation – It is important that greywater systems are validated by
the relevant regulatory body, e.g. the South African Bureau of Standards, SABS,
after conforming to certain standards. This will ensure that validated greywater
reuse systems provide the expected service over the system’s expected design
life and discourage the proliferation of non-validated systems;
 Installation should only be carried out by designated plumbers;
 Clear design and layout specifications need to be provided for the greywater
piped reticulation in relation to other infrastructural services;
 Prevent cross connections: A cross-connection is a physical connection between
a potable water pipe used to supply water for potable purposes, and a greywater
pipe. To prevent this, there is a need to recognise or develop procedures and
regulations that prevent cross-connections. These procedures or regulations
should consider the following:
 The need to develop/recognise a uniform system of labelling and colour-
coding of all pipes and greywater system components.

168
  Where the possibility of a cross-connection between a potable and greywater
pipe exists, authorized backflow prevention devices should be installed on the
potable water pipe to prevent potential backflow of greywater from the
greywater pipe.
 The need to design for horizontal and vertical separation of potable and
greywater pipes. The USEPA and USAID (2004) document requires a 3 m
horizontal interval and a 0.3 m vertical distance between potable and non-
potable pipes that are parallel to each other
 Overflow to sewer: There must be an overflow line from the greywater collection
pipes to the sewer for times when there is an abundance of greywater, when
harmful chemicals are introduced into the collection pipes, or other reasons. The
overflow line should have the capacity to handle the total inflow into the
greywater system;
 Pump systems: The pump system should be able to completely empty the
storage tank if necessary to avoid extended storage of greywater;
 Prevention of accidental ingestion: In addition to pipes being clearly labelled and
colour-coded, appropriate warning signs should be used on all greywater system
components;
 Periodic tracer studies to detect cross-connections between potable and
greywater systems should be carried out;
 Quality: Aim for greywater quality that is visually similar to municipal potable
water. If not possible, ensure there is regular monitoring of treated greywater
quality;
 Greywater reused for toilet flushing may need to be dyed to prevent confusion
with potable water;
 Isolation valves, which allow for repair to certain parts of the system without
affecting other parts, should be designed into the greywater system to minimise
disruptions to normal system functionality; and
 The operational requirements of a greywater reuse system are typically
dependent on the technology used. It is ideal however, that the greywater system
would require minimal operation and maintenance.

169
9.4. Recommendations in brief

In brief, twelve key recommendations from this study in relation to greywater reuse
for toilet flushing were:
i. Develop (or adopt) and enforce regulations and/or guidelines for greywater reuse;
ii. Incorporate greywater reuse for toilet flushing into the design of new buildings;
iii. Do not take the technology for granted. Select a greywater treatment technology

only after a broad scrutiny and clear understanding (on the part of both the
implementing agency and beneficiaries) of available technologies, how they
function, operation and maintenance requirements, and the expected greywater
output quality. There is no “one size fits all” greywater reuse technology.
iv. If possible, only select greywater treatment technologies that have received local

certification by, e.g. SABS or JASWIC;

v. Insist on a purchase and prolonged (e.g. 12 month) service agreement with the
supplier/manufacturer of the greywater system;
vi. Budget for regular operation and maintenance, modification, and replacement

costs when installing especially low-technology and low-cost greywater treatment

systems;
vii. Aim to achieve payback on the system within 8 years. Payback periods of more

than 8 years are most likely to be unattractive to potential beneficiaries;

viii. Ensure greywater is collected from the correct sources within the building and

that sufficient quantities of greywater for the intended use(s) can be collected;
ix. Aim for greywater quality that is visually similar to municipal potable water. If not

possible, ensure there is regular monitoring and assurance of treated greywater

quality and the monitoring of users’ perceptions towards the quality;
x. Ensure there is regular engagement and awareness with beneficiaries before and
after implementation;
xi. Target young people; and

xii. Target non-residential buildings.

9.5. Conclusion

The broad concepts of greywater reuse for toilet flushing, and potential beneficiaries’

170
attitudes towards adopting greywater reuse for toilet flushing as one way of
preserving/improving the environmental, are laudable. However, the experiences
garnered from this study show that implementing greywater reuse for toilet flushing
in South African high density urban buildings already supplied with municipal potable
water, must be approached carefully. Implementation of greywater reuse systems for
toilet flushing should only proceed after a rigorous evaluation and conclusion on
several critical issues including: the availability of regulations or guidelines to which
the reuse system would be accountable; consideration (on the part of both the
implementing agency and beneficiaries) of the trade-offs between implementing low-
technology, low-cost, high maintenance but minimum skill required, and low
greywater quality reuse systems versus other greywater reuse system permutations;
employing accredited greywater reuse systems; targeting the most appropriate end
users, i.e. young people and non-residential buildings; achieving economic viability
based on a maximum payback period of 8 years; and the need for regular
beneficiary awareness and engagement operations. A cursory evaluation of the
above issues would likely result in the failure of such systems.

9.6. Future work

i. A rigorous water quality testing and monitoring programme was not undertaken in
this project in order to determine if the measured greywater parameters
conformed to specific international standards/guidelines. An investigation into this
matter will be useful to assist in the management of the risks and uncertainties
associated with greywater reuse for toilet flushing;
ii. It is anticipated that greywater reuse for toilet flushing will impact on sewerage in
sewered areas. Greywater reuse could potentially result in diminished sewer flow
quantities, which may be insufficient to flush sewers. Diminished sewer flow
quantities may also result in highly concentrated sewer wastewaters which may
lead to increased odours, toxicities and resulting corrosion problems within the
sewers and increased costs for treatment at wastewater treatment works. An
investigation into this matter will be useful to assist in understanding the
implications of implementing city-wide greywater reuse systems for toilet flushing;

171
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 APPENDIX A. DATABASE OF LOCALLY AVAILABLE GREYWATER
TREATMENT UNITS FOR TOILET FLUSHING

APPENDIX A1: LIST OF LOCALLY AVAILABLE GREYWATER TREATMENT

UNIT MANUFACTURERS/SUPPLIERS FOR TOILET FLUSHING

Company Name Email Website

Amitek Solution info@amitek.co.za http://www.amitek.co.za
Aquator MBR http://www.vwsenvig.co.za
Technology
Beacon Watertech
Bio Remediation
Consultants
Biobox W&WW info@biobox.co.za http://www.biobox.co.za
treatment system
Biwater(PTY)LTD corporate.communications@biwater.com www.biwater.co.za
Chem-free Aqua Pty info@chemfreeaqua.com www.chemfreeaqua.com
Clearage project luke@clearaedgeprojects.com www.clearedgeprojects.com
David Harris
Engineering Sytems
Effluent management
Fam System juan@famsys.co.za www.famsystems.com
Flowline Technology http://flowlinetechnology.co.za
Hemcro Africa hennie@hemcro.co.za www.hemcro.co.za
Lilliput Sewage mross@mweb.co.za http://www.lilliput.za.net
treatment
Overberg Water www.overbergwater.co.za
Ozone services office@ozonize.co.za http://www.ozonize.co.za/
Pontos detlev.traut@akwadoc.co.za www.pontos.aquacycle.com
Prentec prentec@iafrica.com
SAME SA mechanical same@netactive.co.za
ErectionPty Ltd
Sannitree info@sannitree.co.za http://www.sannitree.co.za/
brian@sannitree.co.za
Scarab technologies steve@scarabsa.co.za www.scarabsa.co.za
CC gordon@scarabsa.co.za
Siyageza systems CC
Sud-Chemie Water scsa@sc-world.co.za www.seperations.co.za
and process
Technology(Pty) Ltd
Sustainable Living Zeke@sustainableprojects.co.za www.sustainableprojects.co.za
Projects (SLP)
Swan's water peter@swanswatertreatment .co.za www.swanswatertreatment.co.za
treatment(Pty) Ltd
Tecroveer www.tecroveer.co.za
Total Water Solutions info@totalwatersolutions.com.au
Water-Rhapsody info@water-rhapsody.co.za www.water-rhapsody.co.za
Wettech SA erich@wettech-sa.com www.wettech-sa.com
WPCP Water ipmdbn@iafrica.com
Purification Chemical
and Plants

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APPENDIX A2: TEMPLATE LETTER AND QUESTIONNAIRE FOR GREY/WASTE
WATER REUSE SYSTEM MANUFACTURERS/SUPPLIERS

School of Civil and Environmental Engineering

Private Bag 3, WITS 2050. South Africa *Tel: +27 11 717-7104 *Fax: +27 11 717 7045

Date:
Address:

Dear Sir/Madam,
DEVELOPMENT OF A FRAMEWORK FOR SELECTING GREY/WASTE WATER TREATMENT
PACKAGE PLANTS FOR EFFLUENT REUSE IN TOILET FLUSHING

A group of researchers from the Universities of the Witwatersrand, Johannesburg and Cape Town
have been awarded a Water Research Commission project (K5/1821) titled “Dual grey and drinking
water reticulation systems for high-density urban residential dwellings in South Africa”. Within this
project, a framework and database is to be developed to guide decision-makers in the selection of
locally available grey/waste water treatment units that can produce treated effluent for reuse in toilet
flushing. This information, we believe, will assist decision-makers, institutions, individuals, households
and communities intending to implement a dual greywater reticulation system.

As an institution in South Africa involved in the development of grey/waste water treatment units, we
would appreciate if you would provide us with details of one or more of your units that may be used in
producing treated effluent for toilet flushing. The table on the next page may be used as a guide.

Your positive response to this request, at your earliest convenience, will be most appreciated.

Yours truly,

Mr Olawale Olanrewaju; Ph.D. candidate

011 717 7112; 011 717 7104 (Fax); 079 900 7931;OLAWALE.OLANREWAJU@STUDENTS.WITS.AC.ZA

Dr. Adesola A. Ilemobade; WRC K5/1821 Project leader

011 717 7153; 086 553 5330 (Fax); 072 128 2903; ADESOLA.ILEMOBADE@WITS.AC.ZA
DEFINITIONS:
 Greywater – wastewater originating from showers, baths, and hand wash basins;
 Treated greywater – greywater that has passed through some processes to remove impurities
(e.g. soaps & dirt). Treated greywater can be used to meet some water needs (e.g. toilet
flushing);
 A dual water distribution system – separate pipes supplying drinking water & treated greywater
to a building for drinking and non-drinking (e.g. toilet/urinal flushing) water needs respectively.

185
Company/Logo
Features of the package plant
(e.g. treatment technology)
Operating range in L/Hour or
L/Day
Cost of purchasing the plant
Approximate cost of operating the
plant
Maintenance requirements
Energy consumption
Footprint
Storage capacity
Expected functional life of the
plant

Level of skill required for High Moderate Low

operation and maintenance.

Yes No
Ease to Upgrade

Physical quality
Suspended Solids (mg.ℓ-1)
Turbidity (NTU)
Chemical quality
 pH 
 Chemical Oxygen Demand 
Quality of the treated effluent (mg.ℓ-1)
after processing within the Biochemical Oxygen Demand
package plant ( a single value or (mg.ℓ-1)
range would be acceptable) Ammonia (mg.ℓ-1)
Total Nitrogen (mg.ℓ-1)
Free Chlorine (mg.ℓ-1)
Phosphorous (mg.ℓ-1)
Microbiological quality
Faecal Coliform (100 mℓ-1)
Total Coliform (100 mℓ-1)
Physical address:
URL:
Email :

186
 APPENDIX B. PERCEPTION SURVEY QUESTIONNAIRES

APPENDIX B1. QUESTIONNAIRE 1 ADMINISTERED PRIOR TO AND

IMMEDIATELY AFTER GREYWATER SYSTEM IMPLEMENTATION

WRC

AIM: This questionnaire aims to determine (i) perceptions to using treated greywater for toilet/urinal flushing
or garden watering and (ii) willingness to use a dual water distribution system. Your responses will be
confidential.
DEFINITIONS:
 Greywater – wastewater originating from the hand basins.
 Treated greywater – greywater that is filtered and disinfected for toilet flushing.
 A greywater system – separate pipes within a building supplying treated greywater for toilet flushing.

1. To what extent do you agree with each of the following statements? Please tick (√) against the option that is
most applicable to you using the 5-point response scale provided.
Statement

Strongly disagree
Strongly agree

Disagree
Neutral
Agree
Using treated greywater for toilet/urinal flushing or garden watering will have a positive impact on
the environment
Using treated greywater for toilet/urinal flushing or garden watering will make our limited drinking
water resources go further
I am comfortable using treated greywater for toilet/urinal flushing
I am comfortable using treated greywater for garden watering
I am comfortable using treated greywater originating from other buildings for toilet/urinal flushing or
garden watering
I am concerned about people getting sick from using treated greywater for toilet/urinal flushing
I am concerned about people getting sick from using treated greywater for garden watering
Using treated greywater for toilet/urinal flushing or garden watering is disgusting
I will only be prepared to use treated greywater for toilet/urinal flushing or garden watering during a
drought or water shortage
I am comfortable for a dual water distribution system to be installed where I currently reside
STATEMENT BELOW FOR STUDENTS & STAFF AT THE SCHOOL OF CIVIL AND ENV
ENGINEERING ONLY:
I am comfortable with the dual water distribution system that is installed at the School building
I trust the relevant university authorities will ensure that the treated greywater used is safe for
toilet/urinal flushing or garden watering

187
188
2. Might there be any reasons (personal, cultural, religious, etc.) why you may not use treated greywater for
toilet/urinal flushing or garden watering? Please list and briefly explain.

3. Age bracket 15-18 19-21 22-25 26-35 36-45 Above 45

st nd rd th
4. Current status 1 year 2 year 3 year 4 year ___ year
Postgraduate Academic staff Support staff
5. Living in university residence? (for students only) Yes No
6. Gender Male Female
7. Racial category Black White Asian Coloured

8. Make any comments you have on treated greywater use, this questionnaire, the interviewer, etc.

9. Your current university WITS UJ UCT

Thank you for your time and input

189
APPENDIX B2. QUESTIONNAIRE 2 ADMINISTERED ABOUT 3 MONTHS AFTER
GREYWATER SYSTEM IMPLEMENTATION

WRC

AIM: This questionnaire aims to determine (i) perceptions to using treated greywater for toilet flushing and (ii)
willingness to use a greywater recycle system for toilet flushing. Your responses will be confidential.
DEFINITIONS:
 Greywater – wastewater originating from the hand basins.
 Treated greywater – greywater that is filtered and disinfected for toilet flushing.
 A greywater system – separate pipes within a building supplying treated greywater for toilet flushing.

1. To what extent do you agree with each of the following statements? Please tick (√) against the option that is
most applicable to you using the 5-point response scale provided.
Statement

Disagree

disagree
Strongly

Strongly
Neutral
Agree
agree
Using treated greywater for toilet flushing in the student bathrooms will have a positive
impact on the environment.
I am comfortable using treated greywater for toilet flushing.

I am comfortable using treated greywater originating from the hand basins within the
Hillman building.
I will only use the toilet that flushes with greywater when the toilets that flush with normal
water are occupied.
I will only be prepared to use treated greywater for toilet flushing when normal water is
unavailable.
I am concerned about my health when I use the toilet that flushes with greywater.
I am satisfied with the reduction in unpleasant smells emanating from the greywater toilet
while flushing.
I am satisfied with the improvement in the colour of the greywater.
I would consider installing a greywater system in my household one day.

I would recommend greywater recycling for toilet flushing to friends and family
I am confident that the relevant authorities would ensure that the treated greywater used
for toilet flushing is safe.
2 out of 4 times (50%)

1 out of 4 times (25%)

3 out of 4 times(75%)
Every time (100%)

Not at all (0%)

How often do you use the greywater toilet?

190
2. Any comments you would like to make?

3. Age bracket 15-18 19-21 22-25 26-35 36-45 Above 45

st nd rd th
4. Current status 1 year 2 year 3 year 4 year ___ year
Postgraduate Academic staff Support staff
5. Living in university residence? (for students only) Yes No
6. Gender Male Female
7. Racial category Black White Asian Coloured
8. Your current university WITS UJ UCT

Thank you for your time and input

191
APPENDIX B3. QUESTIONNAIRE 3 ADMINISTERED ABOUT 7 MONTHS AFTER
GREYWATER SYSTEM IMPLEMENTATION

WRC

AIM: This questionnaire aims to determine (i) perceptions to using treated greywater for toilet flushing and (ii)
willingness to use a greywater reuse system for toilet flushing. Your responses will be confidential.
DEFINITIONS:
 Greywater – wastewater originating from the bathroom hand basins only.
 Treated greywater – greywater that is filtered and disinfected for toilet flushing.
 A greywater reuse system – separate pipes within a building supplying treated greywater for toilet flushing.

1. To what extent do you agree with each of the following statements? Please tick (√) against the option that is
most applicable to you using the 5-point response scale provided.
Statement

Disagree

disagree
Strongly

Strongly
Neutral
Agree
agree
I am satisfied with the reduction in unpleasant smells from the greywater toilet while
flushing.
I am satisfied with the improvement in the colour of the greywater.

2 out of 4 times

1 out of 4 times
3 out of 4 times(75%)
Every time (100%)

Not at all (0%)

How often do you use the greywater toilet?

Neutral

This is my overall assessment of the greywater reuse system at the School of Civil and
Pass

Environmental Engineering
Fail

2. Any comments you would like to make/suggestions for improvements?

3. Age bracket 15-18 19-21 22-25 26-35 36-45 Above 45

192
 st nd rd th
4. Current status 1 year 2 year 3 year 4 year ___ year
Postgraduate Academic staff Support staff
5. Living in university residence? (for students only) Yes No
6. Gender Male Female
7. Racial category Black White Asian Coloured
8. Your current university WITS UJ UCT
Thank you for your time and input

193
 APPENDIX C: PUBLICATIONS AND OTHER OUTPUT FROM THIS STUDY

Degree related research projects

 Ms K Rahube B.Sc. (Eng) Investigational project, UCT, 2008
 Mr P van Rensburg B.Ing. (Civil Eng) Investigational project, UJ, 2009
 Mr W du Plessis B.Ing. (Civil Eng) Investigational project, UJ, 2010
 Mr S Natha B.Ing. (Civil Eng) Investigational project, UJ, 2011
 Mr M van Rooyen B.Ing. (Civil Eng) Investigational project, UJ, 2011
 Ms D Botes B.Ing. (Civil Eng) Investigational project, UJ, 2011
 Ms I Deka B.Sc. (Eng) Investigational project, WITS, 2010
 Ms T Pitso, B.Sc. (Eng) Investigational project, WITS, 2010
 Ms D Maboea B.Sc. (Eng) Investigational project, WITS, 2011
 Mr P Cebani B.Sc. (Eng) Investigational project, WITS, 2011
 Mrs P Chooka M.Sc. research project, WITS, 2010
 Mr O Olanrewaju Ph.D. research, WITS, ongoing

Conferences
 Adesola Ilemobade, Olawale Olanrewaju and Marietjie Griffioen (2011).
Experiences of greywater reuse for toilet flushing within a university academic
and residential building. Proceedings. Computing and Control in the Water
Industry (CCWI) 2011 conference. Dragan A. Savic, Zoran Kapelan and David
Butler (eds). Centre for Water Systems, University of Exeter, UK. 5-7 Sept.161-
166.
 Ilemobade AA, Adewumi JR and van Zyl JE (2011). The use of dual water
reticulation systems in South Africa: a strategic review. Water Research
Commission 40 year celebration conference. Emperor’s Palace, Kempton Park,
South Africa. 31 Aug-01 Sept (Invited paper).
 O.O. Olanrewaju and A.A. Ilemobade (2011). The costs and benefits of greywater
reuse in a university academic and residential building. 2nd regional conference of
the Southern African Young Water Professionals (SAYWPC) 2011. CSIR
International Convention Centre, Pretoria, South Africa. 5-6 July.
194
 OO Olanrewaju and AA Ilemobade (2010). Modelling reaction and transport of
multiple chemical species in a residential dual drinking and greywater reticulation
system. Proceedings. IWA World Water Congress & Exhibtion, Montreal Canada.
September 19-24.
 OO Olanrewaju, AA Ilemobade, JE Van Zyl and P Kagoda (2009). Perceptions
towards greywater reuse in university residences: a South African case study.
Proceedings. 10th Waternet/WARFSA/GWP-SA Symposium in association with
the International Commission on Water Resources Systems (ICWRS) of the
IAHS. IWRM: Environmental Sustainability, Climate change and Livelihoods.
Entebbe, Uganda. Oct 28 -30.

News articles
“Greywater reticulation systems could save SA’s high quality water”. WRC website.
Press release by Mr Jay Bhagwan. 16 April 2010.
http://www.wrc.org.za/News/Pages/Dualgrey-
anddrinkingwaterreticulationsystemscouldsaveSA%E2%80%99shighqualitywater.as
px. Accessed 01 December 2010.

Awards
 2010. Best poster. 1st Southern Africa Young Water Professionals conference
2010. Water Institute of Southern Africa (WISA). Authored by O.O. Olanrewaju
(Ph.D. student) and A.A. Ilemobade (supervisor)
 2009. 1st prize in the Faculty of Science for Non-Presented Posters. Postgraduate
Cross Faculty Symposium @ WITS. Authored by P.S. Chooka (M.Sc. student)
and A.A. Ilemobade (supervisor)

195