Sunday, August 25, 2013

Introduction to Water Demand

Types of Water Demands:
1. Domestic Water Demand:
As per IS 1172: 1983 as well as National Building Code, domestic consumption under normal condition in an Indian city is expected to be around 135 lpcd (litres/capita/day).
Various domestic uses are Drinking - 5 lpcd, Cooking - 5 lpcd, Bathing - 55 lpcd, Washing clothes- 20 lpcd, Washing utensils - 10 lpcd, washing and cleaning of residences and houses - 10 lpcd, Flushing of toilets etc- 30 lpcd. So total is 135 lpcd.

2. Industrial Water Demand (50 lpcd):
Per capita consumption for industrial needs of a city is generally taken as 50 lpcd.

3. Institutional and Commercial Water Demand (20 lpcd):
20 lpcd is considered sufficient for the institutional and commercial uses but this demand can go as high as 50 lpcd for highly commercial cities.

4. Demand for Public uses(10 lpcd): 10 lpcd is sufficient for the public uses.

5.Fire Demand(1 lpcd) : Fire hydrants are generally provided along the mains at a distance of 100 to 150 meters apart. So this demand is generally ignored while computing the per capita demand of a city and if it is included in the total demand then this total demand is known as co-incidental demand.


Factors affecting per capita demand:
(1) Size of the city
(2) Climatic conditions
(3) Types gentry and habits of people
(4) Industrial and commercial activities
(5) Quality of water supplies.
(6) Pressure in the distribution system.
(7) Development of sewerage facilities.
(8) System of supply
(9) Cost of water
(10) Policy of metering and Method of charging.

To read for the different formulae used to calculate various water demands please this article :  visit Various Types Water Demand Formulae.

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