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Definitions
DRINKING WATER QUALITY
 Raw water: Untreated water from suspicious sources such as rivers, lakes or
What is the coverage of access to improved drinking from unprotected wells and springs
Drinking water in Ethiopia?
 Contaminated water: Water which may contain harmful microorganisms or
Status in the world? toxic chemicals which make it unfit for use.

Developing countries ?  Polluted water:-Water that has come in contact with substances that alter its

Sub-Saharan ? physical qualities, so that it changes in color, level of turbidity, taste or smell

What are the challenges?  Clear water:-Water that has a sparkling appearance to the eye. Such water

may be clean or contaminated

 Clean water:-Water that is free of disease causing organisms

Definition…. Drinking water

 Waterborne diseases are a major killer, particularly of young
 Palatable Water:-Water which is pleasant to drink (has good
children
taste). It is not necessarily clean or potable. It can be pleasant
 Diarrhea represents the largest share of this disease burden
to drink, nevertheless may be contaminated
 4 billion cases and 1.9 million deaths each year of children under
 Potable water:-This is drinkable water. Water which is free at 5 years, or 19% of all such deaths in developing countries
all times from any harmful substances (pathogenic organisms  Unsafe drinking water also contributes to more than 25 million cases
or chemicals). and 250,000 deaths annually of enteric fevers (typhoid and
paratyphoid), as well as to much of the disease burden from
cholera, poliomyelitis, and hepatitis A and E

Drinking water Drinking water

First, huge disparities exist in coverage of improved  Second, complete information about drinking water
water supply sources: safety is not available
 90 percent or more in Latin America and the
Caribbean, Northern Africa and large parts of Asia
 Systematically testing the microbial and chemical
 61 percent in sub-Saharan Africa
for global monitoring
 86 percent in developing world  Assessing the quality of water at the national level
 63 percent in countries designated as ‘least in all countries is expensive and logistically
developed’. complicated
 Similar disparities are found within countries between
 proxy indicator for water quality was agreed
the rich and poor and between those living in rural and
urban areas. upon for MDG monitoring.

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Introduction Drinking water…

IMPROVED DRINKING WATER SOURCES
 This proxy measures the proportion of the population  Piped water into dwelling, plot or yard
using ‘improved’ drinking water sources  Public tap/standpipe

 Tube well/borehole
 defined as those that, by the nature of their construction,
 Protected dug well
are protected from outside contamination, particularly
 Protected spring
faecal matter.  Rainwater collection
 Still 780 million people remain unserved UNIMPROVED DRINKING WATER SOURCES
 Unprotected dug well
 However, some of these sources may not be adequately  Unprotected spring
maintained and therefore may not actually provide ‘safe’  Cart with small tank/drum

drinking water.  Tanker-truck

Surface water (river, dam, lake, pond, stream, canal, irrigation channels)
 As a result, it is likely that the number of people using 

safe water supplies has been over-estimated

Ten countries are home to two thirds of the global population

without an improved drinking water source Drinking Water Quality….
 Drinking water has received considerable attention recently
 However, there is a marked difference between available and
demand
 progress towards sustainable management of this vital resource
has been less than adequate.
 Over the past few decades, global drinking water consumption
has outpaced population growth
 misuse and mismanagement have resulted in a rapid and
widespread decline in source-water quality and supply

Drinking Water Quality and Sustainability Drinking water quality….

 Climate change will bring about broad impacts on society
Overall, three fundamental points are clear.
through a changing water cycle.
 First, the current approach to the management and consumption of
freshwater supplies is small-scale and exploitative.  current spatial patterns of water quality and quantity will be
altered through changes in frequency, duration, intensity and
 Second, this approach to water is unsustainable because of the
profound impacts of human growth and activity on this resource. timing of precipitation events.

 Third, the overriding factors that will continue to determine the  In some regions where water resources are already scarce, this

future of freshwater resources are human population growth and may lead to intolerable water shortages.
distribution, and economic development.  In other areas where the infrastructure does not exist to capture
less frequent, but more intense precipitation events

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Water quality ….. Water quality…

 Long-range atmospheric transport is resulting in the movement  Population growth and demographics also have substantial impacts
on water supply and quality.
of persistent organic pollutants (POPs) across catchment
 Almost two billion people (30%) now face water scarcity, and with
basins and aquatic ecosystems
current growth, it is estimated that by 2025 water stress will affect
 Eutrophication and pollutants change aquatic systems towards two thirds of the human population
decreased stability, water quality and food web diversity,  The current migration from rural areas to urban centre is creating
and more outbreaks of invasive and noxious species nodes of high freshwater demand and intense pollutant stress.

 Politics at local, regional and national levels generate conflicting

water-related issues

Threats drinking water

 These threats are recognized at three levels:

i) ultimate sources (e.g., agricultural, industrial and municipal etc),

ii) proximal contaminants (e.g., nutrients , toxins, endocrine

disruptors, pathogens, etc.)

iii) Environnemental modifiers (e.g., climate change).

 these factors closely linked.

Threats to drinking water Water quality…..

 the delivery of safe drinking water has become increasingly
dependent on the widespread use of disinfection treatment
 The primary role of source water integrity has been largely
overlooked
 approach clearly begins with source protection, followed by a
systematic development, installation and evaluation of
treatment technologies for contaminant removal and monitoring
 source protection, and of a need to adopt a “multi-barrier
approach” to drinking water safety has a vital importance

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Multiple barrier approach to safe drinking water

Impurities of Water

 Water is not absolutely pure in nature

 It gathers impurities as it goes through its natural cycle

These impurities can be divided in to two:

i. Suspended impurities:-
 Microorganisms- from air, soil
 Suspended solids – minute particle of soil, clay
 Algae – which can cause taste, color and turbidity

Impurities of Water
Diseases associated with water
Unfortunately not all water helps humans to survive
Dissolved impurities:- 

 Water from contaminated sources cause numerous disease and

 Gases -Co2, O2, H2 ., CH4 etc.
untimely deaths.
 Minerals – get access through percolation e . g Ca,
 About 80% of all disease and 1/3 of the death in developing
Mg, Na, K salts of toxic elements, pesticides,
countries are associated with unsafe water
detergents and others (fluoride, nitrate etc)
 In countries like Ethiopia, since majority of the peoples get their
 Plans dyes – originates from plants which grow in or
water supply from unprotected sources, water borne diseases
around the water which cause acidity and color
are the most significance public health problems of the present.

Disease …. Disease…
I. Water-borne diseases:- due to ingestion of faecally contaminated water IV. Water-related vector borne diseases:- water serve as development and
breeding site of insects(water is essential of the completion of their life
e. g cholera, typhoid, infectious hepatitis , polio mellitus, bacillary
cycle of vectors) e . g malaria, yellow fever, onchoserciasis, leshimaniasis,
dysentery, amoebiasis, giardiasis etc
sleeping sickness etc.
II. Water-shortage (water-washed) diseases :-due to lack of adequate
V. Chemical constituents in water either excess or shortage:- water
supply of water and poor sanitation(personal hygiene) diseases like: eye
contaminated through discharges or infiltration of organic compounds
infection-(trachoma, conjunctivitis); skin infection-(scabies, ringworms);louse
and pesticides.
borne disease-(RF)
Examples: Fluoride :
III. Water-impounding (water-based) diseases :-caused by aquatic
o Excess – dental fluorosis(mottled teeth), skeletal fluorosis, crippling
organism that spend part of their life cycle in water and other part as
fluorosis
parasite of animals. e . g schistosomiasis, druncuculiasis(guinea worm)
o Shortage – dental caris(tooth decay)

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Disease… water treatment for municipal water supply

Nitrate excess:- methomoglobenemia(blue baby syndrome)  Water treatment: is the process of removing all those
confined to infants less than three month. substances (biological, chemical or physical) which are
potentially dangerous or undesirable in water supplies
There fore, in planning a community water supply program the
for human and domestic use.
following conditions should be considered:  Surface waters are never pure, deserve adequate
 Quality – safe and wholesome treatment if they are intended for domestic purposes.
 The impurities vary from disease causing microorganisms
 Quantity – adequate and continuous
and dangerous chemicals to substances which are
 Convenience –accessible and affordable, culturally acceptable undesirable from points of view of color, taste, odor, but
which are physiologically harmless.

Water treatment Typical water Treatment Process/steps

The main objectives for water treatment Surface raw water

source: lake, pond, Course screening Fine
o To remove pathogenic organisms and prevent water- river screening
borne diseases.
o To remove substances which impart color, taste, or odor
to the water.
o To remove excess or undesirable chemicals or minerals Sedimentation basin Coagulation and Aeration and
floclotion pre chlorination
form the water.
o To regulate essential elements or chemicals (remove
excess, limit amount or remove unwanted): E.g
fluoridation/ defluoridation or softening or water
Post – T0 distribution
o To remove excess or undesirable dissolved gases. Filtration chlorination/disinfection system

Treatment of water on a small scale Cont.…

 For economic reasons, large scale water treatment procedures do not 2. Filtration: Using sand filters or candle (ceramic) filters.
exist and can not be practical for poor communities in developing 3. Storage and sedimentation

countries like Ethiopia 4. Exposure to sun-light

5.Chemical disinfection: Chemical disinfection compounds such as chlorine, iodine,
 Thus, Treatment of household water supplies may be effected by the
silver salts and potassium permanganate etc., may be used
following methods, used singly or in combination, depending on the Even though there are many chemicals that used, chlorine is disinfectant of choice
reliability of each method because:-
o Easy to handle, transport , available
1. Boiling: Is one of the most reliable methods of disinfecting water on
o Comparatively cheap
a small scale provided it is brought to the boiling point and is kept
o Effective and long lasting
15-20 minutes
o Simple to apply and relatively easy

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cont… Quality Control / Control of drinking water

 The assessment of potability of drinking-water is usually
 But there are factors that influence the disinfecting power
determined by a combination of results obtained from
of chlorine like:-
 laboratory analysis (i.e. physical, chemical microscopic and
1. pH of the water
bacteriological)
2. The quality of the water
 sanitary surveys of the water source
3. Water temperature
1. physical analysis:-determining substances which affect the
4. Presence of ammonia
physical property of the water such as color, taste or odor.

Quality control… Quality Control

2. Chemical analysis: is concerned with the determination  Microscopic analysis: Refers to the identification and
determination of those microscopic organisms such as
of acidity- alkalinity, PH, hardness, dissolved oxygen, algae, fungi; plankton, protozoa, etc. which may be
present in the water. These organisms impart
hydrogen sulfide, chloride, nitrates, nitrites, ammonia, objectionable taste, odor or color to the water.
 Bacteriological analysis: To determine the degree of
chlorine residual, fluoride, iron, manganese, and toxic contamination of water with wastes of human or animal
substances such as arsenic, lead, mercury, pesticides, etc origin.
 Sanitary survey of a water supply system: This is the
present in the water intended for domestic use complete, extremely careful and detailed investigation
of the entire water supply system, form the source to
the consumer, in order to detect the presence of actual
or potential sources of contamination.

Community drinking water Supply Drinking water standard setting

 How standards are set?
Objectives:
1. Health criteria:
 Safety: ???
 Physical, chemical, biological
 Adequateness: ????
2. Feasibility:
 Accessibility: ???
 Acceptability: users
 Q? Criteria to meet the above objectives
 Economical: Cost inputs

3. Physical access: distance to home: ???

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Drinking water supply surveillance Role of Public health manager in water supply

 Source quality assurance

 Why surveillance? What is it?
 Water supply quality assurance
 Regulatory function
 Epidemic investigation Vs water?
 Methods used:
 Small scale water supply development
1.Sanitary surveillance: system integrity; source of contamination
 Enhancing community participation: planning, implementation,
2.Laboratory surveillance: quality assurance
use, M & E
3.Epidemiological: rapid method
 Hygiene Education

Indicators
Country status: Drinking water
 Input -------- output -------- outcome --- impact  Problem assessment

 Input = resource for wash, hardware and software , M & E indicators: basics
labour forces  Accessibility
Output = construction coverage  Adequateness
Outcome = continued to use  Coverage
Impact = reduced child mortality, diarrhea  Quality of water

How much water? (international

Indicators definitions practices)
Definitions  No access: <5 l/c/d
 Accessibility: time/distance
 Survival allocation: 7.5 l/c/d
 Basic access: 20 l/c/d
 Adequateness: availability/quantity
 Intermediate access: 50 l/c/d
 Coverage: % with improved water supply (HH connection,  Optimum access: > 100 l/c/d
public standpipes, protected underground water sources, rain  <1000m, 5-30 minutes walking distance
water collection)  Where are we? Given <10 l/c/d
 Quality of water: biological/physical/chemical

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KAP towards sanitation(MOH, KAP survey WIBS) Drinking water handling at house hold level
 30-75% of respondents in different Weredas did not know In a study in 1999:
that diseases are associated with drinking water
 Common containers: clay pot, Jerricans
 23 to 87% of respondents did not know any method of
 15-20 litres capacity
drinking water treatment.
 HH water containers covered: 57%
 > 60% of respondents in most of rural Wereda did not know
 Pouring method: 88%
that diseases can be transmitted through human excreta

Summary
 Drinking water is increasingly impacted by human activities

 Climate change, urban and industrial development threaten drinking

water integrity and sustainability.

 Populations, consumption and resource degradation are increasing as

if there were no limits to the supply of clean water.

 The development of a long-term approach to sustainable water use

requires national and international collaboration.

 At the same time, the causes and mitigation of source-water

degradation need to be addressed.