1.

Water supply

Sudha Goel, Ph.D. (Env. Eng.)

Civil Eng. Dept., IITKgp
Kharagpur 721 302
 Water use and reuse
Well or
surface Water treatment Distribution
water plant network
intake

Recycle
Reuse for Wastewater Sewer
Consumer
irrigation treatment plant system

Discharge to
land, surface
water or sea
2
 Objectives
 Water supply: adequate quantity and safe, potable water
 Sourcing and source protection
 Treatment
 Disposal of sludges
 Wastewater treatment: to mitigate
 Public health concerns – contamination of water
supplies (SW and GW), and soil,
 Environmental concerns - Ecological conservation,
recreational requirements

3
Design of water supply and wastewater
systems
 Identify need (demand) in terms of QUANTITY AND QUALITY
 Identify water SOURCES that can fulfill needs
 Source Protection Programs
 Criteria for water source selection include:
 Quantity
 Quality
 Location
 Cost of development, collection and distribution
 Sustainability
 Wastewater systems
 Estimated as % of water used
 Where will the wastewater be discharged? Treatment standards
are based on that.

4
 Water Usage
 Withdrawals = consumption + returns
 Withdrawal = water extracted from surface or ground water
bodies
 Consumption = water used but not returned (eg., drinking, cooking,
evaporation, transpiration, irrigation)
 Returns (non-consumptive uses) = water returned to water body
and can be used in the future
 Compare per capita TOTAL water use at the national level:
 Developed (e.g. US) = 1280 gal/cap-d = 1280x3.785 (L/gal) =
4845 L/cap-d
 Developing (e.g. India) = 609 m3/cap-year = 1669 L/cap-d

 Compare per capita water use (individual scale):

 Developed (e.g. US) = 227 L/cap-d (DeOreo et al., 1996)

 Developing (e.g. India) = 100 L/cap-d (Goel, 2015)

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 WITHDRAWAL
CONSUMPTION
RIVER

RETURN

THUMBRULE: MUNICIPAL WASTEWATER DISCHARGES ARE

APPROXIMATELY 80% OF THE TOTAL WATER USAGE
The actual % can range from 50 to 100%; depends on how much water is used for
gardening and horticulture, population density. In major Indian cities – wastewater
is 87% of water supplied (CPCB, 2009)

6
Offstream water use involves the withdrawal or diversion of
water from a surface or ground water source for:
 Domestic and residential uses (consumptive)
 Industrial uses (both)
 Agricultural uses (consumptive)
 Energy development uses (both)

Instream water uses are those which do not require a diversion or

withdrawal from the surface or ground water sources, such as:
 Water quality and habitat improvement, i.e., eco-conservation
 Recreation
 Navigation (Quality not an issue)
 Fish propagation

Quality is dependent on water use, i.e., not all water uses

require the same water quality

7
 Indian water uses
Estimated water requirements in India for 2010[1]

Sectors or uses of Water requirements, % use

water BCM[2]
Irrigation 550 78.3
Domestic 42.5 6.04
Industries 37 5.3
Power 18.5 2.6
Navigation 7 1.0
Ecology 5 0.71
Evaporation losses 42 6.0
Total 702 100
]

[1] Based8 on (UNICEF, 2013); National Commission for integrated water resources development plan, 1999
[2] Billion cubic meters
 Source water issues
 India is no longer a predominantly river-based economy
 Most of the water usage is for irrigation and agriculture (90.4%)
 Withdrawals from GW are now 33%

 61.6% of the net irrigated area in 2011-12 was irrigated by well

water
 Domestic consumption of groundwater is also rising, bringing other
issues in its wake; results of survey in 14 Aug 2017
Source Number Percentage
Surface water only 58 34
Ground water only 38 22
Surface and ground water 75 44
171
Lack of treatment in residential areas or at the individual level
 Contamination of GW

9  Environmental impacts of increasing GW use are now recognized

Source water issues
 Two of the three National Mission pollutants are
geogenic and found mostly in groundwater
 Geogenic: Arsenic and fluoride
 Anthropogenic: Nitrate enters groundwater due to excessive
fertilizer application, or leachate from open solid waste
dumps, etc.

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ESTIMATES OF TOTAL
WATER WITHDRAWALS
IN INDIA

Panikkar, A. (2012). Water profile of India. FAO.

11
Retrieved from
http://www.eoearth.org/view/article/156948/
 Source distribution

12
Central Water Commission, 2015. Water and related statistics
 Domestic consumption of water (L/capita-day)
Use IS 1172- IS 1172- AWWA, 1999, gcd
1983, Lcd 1993 (India),
Lcd
Drinking 4.5 5 (2.5%)
Cooking 49.5 5 (2.5%)
Bathing 75 (37.5%) 12.8 (18.5 %)
Washing clothes 25 (12.5%) 15.0 (21.7 %)
Washing utensils 15 (7.5%) 1.0 (1.4 %)
Cleaning homes 15 (7.5%) 10.9 (faucet 15.7 %)
Gardening 15 (7.5%) Outdoor use (2.3%)
Flushing toilets, etc 22.5 45 (22.5%) 18.5 (26.7%)
Losses 9.5 (13.7%)
Public uses – street 22.5
cleaning, fires,
flushing sewers,
fire extinguishing
Industry and 22.5
commerce
Animal maintenance 13.5
Total 135 200 (100%) 69.3 (100%) or 262
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Water demand
 Thumbrules for calculating total water
demand for a town or city
 Domestic requirement – 50% of total
 Industrial/commercial requirement – 20 to
25 % of total
 Public uses – 10% of total
 Losses and leaks – 15% of total
 Fire demand to be calculated based on
empirical formulae provided

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 Factors affecting domestic water use
 Population
 Nature of activities
 Climatic conditions
 Economic conditions
 Cultural conditions
 Industrial and commercial requirements
 Env protection, and quality issues
 Water conservation (habits and policies)
 Method of charging: flat or fixed rate versus metered systems
 Pressure
 Development of sewerage systems
 Supply period: intermittent versus continuous systems

In India, low income groups (IS Code req) – 135 Lcd (we know it can be as low
as 30 lcd in reality). Total water requirement for all uses is 335 Lcd or Lpd
(Table 2.5, SKG). 15
Population forecasting methods
1. Exponential (best for developing countries
and urban areas)
2. Arithmetic progression
3. Geometric progression
4. Incremental increase
5. Ratio method
6. Changing rate of increase method
7. Graphical method (curve-fitting and
extrapolation)
8. Logistic curve method
16
Shaban and Sharma, June 2007, Water consumption patterns in domestic
households in major cities, Economic and Political Weekly, 2190-2197.
17
Shaban and Sharma, June
2007, Water consumption
patterns in domestic
households in major cities,
Economic and Political
Weekly, 2190-2197.

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19
http://www.idfc.com/pdf/report/2011/Chp-18-Industrial-Water-Demand-in-India-
20
Challenges.pdf
 Per capita consumption w.r.t.
population and sewerage
 Communities with population <20,000 and no flushing
system
 40 lpcd (with standpost)
 70 to 100 lpcd (through house connection)
 Communities with population >20,000 and <100,000 and
full flushing system
 100 to 150 lpcd
 Communities with population >100,000 and full flushing
system
 150 to 200 lpcd

IS 1172, 1993 21
 Factors affecting losses

 Leakage at joints and corrosion of pipes

 Pressure in distribution systems: higher pressure leads to higher
losses due to leakage
 System of supply: Intermittent supply leads to fewer leakage
losses
 Metering: unaccounted water loss is easy to monitor, leaks can be
detected and fixed
 Unauthorized connections are reduced where supply is metered;
easy to detect illegal connections where supply is metered.

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Per capita water supply in Indian cities

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 Design parameters
 Design Period
 Large dams and conduits: 25 to 50 y
 Wells, distribution systems, filter plants: 10 to 25 y
 Pipes more than 300 mm in dia.: 20 to 25 y
 Average: 30 years, cannot exceed life of structures
 Design period can be incremental or total
 Population size for end of design period

 Forecasting of future populations: different methods

 Exponential, in general
 Flow requirements

 Domestic, industrial and commercial requirements

 Fire-fighting requirements
 Pressure requirements

 Water quality requirements

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 Fire demand
Fire demand is generally computed based on population
 National board of Fire Underwriter’s formula
Q = 1020 √P (1-0.01 √P)
Where Q = fire flow rate, gpm (1 US gallon = 3.785 L)
Q = 3861 √P (1-0.01 √P); Q = fire flow rate, lpm
where P = population in thousands
 Freeman formula: Q = 1136.5 (P/5 +10)
 Kuichling formula: Q = 3182 √P
 Ministry of Urban Development Formula: Q = 100 √P
 Indian standards (IS 9668, 1990): 1800 L/min for every 50,000
population and an additional 1800 L/min for each 1 lakh population in
excess of 3 lakhs. For towns with population ≤ 1 lakh, total
requirement should be doubled. Fire reserve should last for at least
2 hours (2 to 10 h, Table 4.13, QMZ, 2004)
 At least one static water tank with capacity of 220,000 Liters/km2 area.
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IS 9668, 1990
 Temporal variations in demand
 Seasonal: based on climate and crop requirements,
commercial, industrial (cracker industry), tourist spots
(religious or secular), institutional (schools, colleges,
camps) activities can be seasonal
 Daily: Fig 2.1 (SKG) and fig. 2.1 (KND). Trend is
slightly different from the sources noted below. Daily
max can range from 1.8x daily average (SKG) to 2.5
times daily average (KND).
 Generally two peaks in a day: higher peak in the
morning (0500 to 1100) and (1700 to 2300) and lowest
flow (2300 to 0500) – based on VW, SKG and AWWA
(no definitive information). Specific and average
trends can be different for all the reasons discussed
previously. 26
27
24-h water demand in summer vs.
winter (Vancouver, CA)

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 Demand factors (DF)
Based on historical municipal records
 DF = Qevent/Qaverage
 Maximum day demand = average rate of all
recorded annual max day demand; 1.2 to 3
 Minimum day demand = average rate of all
recorded annual min day demand; 0.3 to 0.7
 Peak hour demand = average rate of all
recorded annual max hour demand; 3.0 to 6.0
 Max day of record = highest recorded max
day demand; <6.0
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MZ, 2010
 Peaking factors (PF)
 PF is applied to the average daily flow rate to
design or size different components of water
supply and wastewater systems
 Qdesign = Qaverage* PF
Treatment Water Treatment Wastewater
Process Plant treatment plant
Plant hydraulic Qmax,d*(1.25 to 1.5) Qmax,
capacity instantaneous
Treatment Qmax,d Qaverage* (1.4 to 3.0)
processes
Sludge pumping Qmax,d Qaverage* (1.4 to 2.0)

30
MZ, 2010
Sincero and Sincero, 1996 31
Solution
 Arrange data in serial order from highest to lowest
and give each data point a rank
 Calculate 90th and 75th percentile of the data
 Design can be based on the absolute maximum of a 50 or 100
year data set or
 It can be based on maximum day or maximum hour calculated
on the basis of 90th percentile (economics is the deciding
factor)
 To calculate percentile: Top 5 out of 50 data points
would be 90th percentile while top 12.5 data points
would be in the 75th percentile

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 Fire demand (see details in Hammer2)

Fire demand can also be computed based on

construction materials (Sincero and Sincero 1996).
 F = 3.7*10–3*C*A0.5, where
 F is the flow rate for fire-fighting (m3/s),
 C is a dimensionless coefficient related to type of
construction material:
 1.5 for wood frame construction
 1.0 for ordinary construction
 0.8 for non-combustible,
 0.6 for fire-resistive construction,

 A is total floor area excluding the basement (m2).

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QMZ, Hammer2
END

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