Ch1 Water Supply

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1. Water supply

Sudha Goel, Ph.D.

Assistant Prof. (Env. Eng.)Dept. of Civil Eng., IITKgp

Kharagpur 721 302


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Objectives

Water supply: adequate quantity and safe, potablewater 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

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Design of water and wastewater systems

Identify need (demand) in terms of QUANTITY AND

QUALITY Identify SOURCES that can fulfill needs

Source Protection Programs

Criteria for source selection include: Quantity

Quality

Location Cost of development, collection and distribution

Sustainability

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Water Usage Withdrawals = consumption + returns

Withdrawal = water extracted from surface or groundwater bodies

Consumption = water used but not returned (eg.,drinking, cooking, evaporation, transpiration, irrigation)

Returns (non-consumptive uses) = water returned towater body and can be used in the future

Compare per capita water use: Developed (e.g. US) = 1280 gal/cap-d = 1280x3.785 = 4845

L/cap-d

Developing (e.g. India) = 609 m3/cap-year = 1669 L/cap-d

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Offstream water use involves the withdrawal or diversion ofwater 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 orwithdrawal from the surface or ground water sources, such as:

Examples of non-consumptive water uses Water quality and habitat improvement, i.e., eco-conservation Recreation Navigation (Quality not an issue) Fish propagation Hydroelectric power production (Quality not an issue)

Quality is dependent on water use, i.e., not all water usesrequire the same water quality

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Indian water uses

India: State of the Environment (2001) 6


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Designated-Best-Use

Class of

water Criteria

1. Total Coliforms Organism MPN/100ml shall be 50 or less

2.pH between 6.5 and 8.5

3.Dissolved Oxygen 6mg/l or more

4.Biochemical Oxygen Demand 5 days 20C 2mg/l or less


2. pH between 6.5 and 8.5


4. Biochemical Oxygen Demand 5 days 20C 3mg/l or less


2.pH between 6 to 9


4. Biochemical Oxygen Demand 5 days 20C 3mg/l or less

1.pH between 6.5 to 8.52. Dissolved Oxygen 4mg/l or more

3.Free Ammonia (as N) 1.2 mg/l or less

1.pH between 6.0 to 8.5

2.Electrical Conductivity at 25C micro mhos/cm Max.2250

3.Sodium absorption Ratio Max. 264. Boron Max. 2mg/l

Table 1 : Use based classification of surface waters in India

Drinking Water Source without

conventional treatment but after

disinfection

Propagation of Wild life andFisheries

D

Irrigation, Industrial Cooling,

Controlled Waste disposal

E

A

Outdoor bathing (Organised) B

Drinking water source after

conventional treatment and

disinfection

C

7CPCB


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Domestic consumption of water (L/capita-day)

Use IS 1172-

1983, Lcd

IS 1172-

1993 (India),Lcd

AWWA, 1999, gcd

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 (

Flushing toilets, etc 22.5 45 (22.5%) 18.5 (26.7%)

Losses 9.5 (13.7%)

Public uses street

cleaning, fires,

flushing sewers,fire extinguishing

22.5

Industry and

commerce

22.5

Animal maintenance 13.5Total 135 200 (100%) 69.3 (100%) or 262


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Factors affecting losses

Leakage at joints and corrosion of pipes

Pressure in distribution systems: higher pressure leads to higherlosses due to leakage

System of supply: Intermittent supply leads to fewer leakagelosses

Metering: unaccounted water loss is easy to monitor, leaks can bedetected 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 consumption wrtpopulation and sewerage

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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 isslightly different from the sources noted below. Daily

max can range from 1.8x daily average (SKG) to 2.5times daily average (KND).

Generally two peaks in a day: higher peak in morning

(0500 to 1100) and (1700 to 2300) and lowest flow(2300 to 0500) based on VW, SKG and AWWA (nodefinitive information). Specific and average trendscan be different for all the reasons discussed

previously. 14


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Per capita water supply in Indian cities

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Ch1 Water Supply