Estimation of water quantity for a Town: Quantity of water can be estimated from following two factors:1. Rate of Demand2. PopulationThe requirements of water for various uses are properly analyzed and the rate of consumption per head is worked out. The number of persons to be served by the scheme are calculated and estimate of future population is worked out with the help of suitable method.

Rate of demand:A small quantity of water is required by a man under normal conditions for his personal use. But his demand of water for other purposes will naturally depend upon the standard of living and degree of culture. The demand for various purposes is divided into:1. Domestic purposes2. Civic or public purposes3. Industrial purposes4. Business or trade purposes5. Losses & wastages

1. Domestic Purposes: It is about 40% to 50% of total water requirement per capita (person) per day. It can be subdivided as follows:(i) D2. 3.