Unit Water Demand

When the proposed project is in a community with an existing water supply, the  historic records of water consumption provide the best estimate of water use. Conversion of total demand to per capita demand (liters per capita per day, Lpcd) allows for the separation of population growth from the growth in unit consumption. If the proposed project is to improve the water quality, consideration
should be given to the likelihood that unit demand will increase because of the improved water quality. In the absence of existing data for the community, nearby communities with similar demographics are a good alternative source. When the demographics differ in some particular aspect such as a higher or lower density of commercial facilities or a major industrial component, adjustment
in the total demand should be appropriately made.

Due consideration must be given to the following local factors that modify gross estimates:

  • Climate
  • Industrial activity
  • Meterage
  • System management
  • Standard of living

The extent of sewerage, system pressure, water price, water loss, age of the community, and availability of private wells also influence water consumption but to a lesser degree.

The Unit water demand for domestic, non-domestic and industrial purposes , as collected from different sources is as follows;

 

CPHEEO

The CPHEEO Manual for Water Supply & Treatment recommends following values for unit water demand for domestic & Non-Domestic consumers;

  • Towns with piped water supply but without sewerage – 100 LPCD
  • Cities provided with piped water supply with existing/contemplated sewerage system – 135 LPCD
  • Metropolitan & Mega Cities with piped water supply with existing/contemplated sewerage system – 150 LPCD

It further recommends that above figure exclude Non Revenue Water, which should be limited to 15%. These figures include water supply for commercial, institutional and minor industries. Any bulk supply to such establishments is required to separately assessed and included.

National Building Code, India

IS 1172:1993 – “CODE OF BASIC REQUIREMENTS FOR WATER SUPPLY, DRAINAGE AND SANITATION”  provides recommendations for values for water demand.

Domestic Water Demand

A minimum of 70 to 100 litres per head per day may be considered adequate for domestic needs of urban communities, apart from non-domestic needs as flushing requirements. As a general rule the following
rates per capita per day may be considered minimum for domestic and non-domestic needs:

a) For communities with population upto 20000 and without flushing system:
1) water supply through  standpost 40 lphd, Min
2) water supply through house service connection - 70 to 100 lphd
b) For communities with population 20000 to 100000 together with full flushing system - 100 to 150 lphd
c) For communities with population above 100000 together with full flushing system - 150 to 200 lphd
NOTE— The value of water supply given as 150 to 200 litres per head per day maybe reduced to 135 litres per head per day for houses for Lower Income Groups (LIG) and Economically Weaker Section of  Society (EWS), depending upon prevailing conditions.
Out of the 150 to 200 litres per head per day, 45 litres per head per day may be taken for flushing requirements and the remaining quantity for other domestic purposes.
Water Supply for Buildings Other than Residences
Minimum requirements for water supply for buildings other than residences shall be in accordance with Table below;
S.No. Type of Building Consumption per day, litres
1 Factories where bath rooms are required to be provided  45 per head
2  Factories where no bath rooms are not required to be provided  30 per head
3  Hospitat(includinglaundry):
a  Numberof beds not exceeding100  340 per head
b  Numberof beds exceeding100  450 per head
4  Nurses’homesand medicatquarters  135 per head
5  Hostel  135 per head
6  Hotel (Up to 4 Star)  180 per head
7  Hotel(5 Starand above)  320 per head
8  Offices  45 per head
9  Restaurant  70 per seat
10  Cinemas,concerthalts andtheatres  15 per seat
11  Schools:
a  Day Boarding  45 per head
b  Boarding School  135 per head

 

Water Supply Requirements of Traffic Terminal Stations
The water supply requirements of traffic terminal stations (railway stations, bus stations, harbours, airports, etc) include provisions for waiting rooms and waiting halls. They do not, however, include requirements for retiring rooms. Requirements of water supply for traffic terminal stations shall be according to Table below;
S.No. Nature of Terminal/Station Where Bathing Facilities are provided, litres/capita Where Bathing Facilities are not provided, litres/capita
 1 Intermediate stations (excluding mail and express stops)  45  25
 2 Junction stations and intermediate stations where mail or express

stoppage is provided
 70  45
 3 Terminal stations  45  45
 4 International and domestic airports  70  70

NOTES

1 The number of persons shall be determined by average number of passengers handled by The station daily, due
consideration may be given to the staff and vendors likely to use facilities.
2 Consideration should be givenfor seasonal peak requirements
Water Supply for Fire Fighting Purposes
1 The Authority shall make provision to meet the water supply requirements for fire fighting in the city area, depending on the population density and types of occupancy.
2 Provision shall be made by the owner of the building for water supply requirements for fire fighting purposes within the building, depending upon the height and occupancy of the building, in conformity with the requirements laid down in Part 4 ‘Fire and Life Safety’.
3 The requirements regarding water supply in storage tanks, capacity of fue pumps, arrangements of wet riser-cum-down-comer and wet riser installations for buildings above 15 m in height, depending upon the occupancy use, shall be in accordance with Part 4 ‘Fire and Life Safety’.