Water is used for industrial and municipal purposes. The largest water requirement is for municipal use but the standard of purity required for this purpose is quite different from that demanded for industrial and commercial use.
In industry more than half the water is used in chemical plants for the purpose of cooling. A large volume of water is also used for the purpose of dilution and making solutions. While for the first purpose the composition of cooling water is of no importance, in the second, the water used should be reasonably pure.
The availability of water, both in quantity and quality, is one of the prime factors in deciding the growth of towns and cities as well as industries. For chemical industries, the available water must be as near as possible to the factory site and should also be soft. Otherwise the manufacturing cost will increase.