The cost of the supplying water consists to very large extent of fixed costs & only to small extent of variable costs that depend on amount of water consumed. Quality of drinking water has a dimension microbiological and physico-chemical. There are thousands of parameters for water quality. In public water systems, water must be disinfected at least - usually through the use of chlorination or the use of ultraviolet light - or it may be necessary to undergo treatment, especially in the case of surface water.