In Planning a water supply scheme, it is essential to first of all search a source of water in vicinity of the town or city for which the scheme is to be designed. sometimes, the water may be available nearby, and sometimes it may be far away. further it may be an underground well, or it may be a river, stream or a lake. it is therefore necessary to seek out all the possible sources and evaluate each in terms of quantity, quality and cost, and then to take a final decision regarding upon the availabilities of water in those sources and the demand requirements of the town or the city.
suitable systems should then be designed for collecting, transporting and treating this water. The treated water is finally distributed to the residents and industries depending upon their requirements, through a network of distribution system. The essential elements of a public water supply scheme may therefore consist of intakes and reservoirs, a water treatment plant having screening, sedimentation, filtration, disinfection units, etc. elevated tanks and stand pipes which provide storage to meet peak demands occurring for limited periods, valves which control flow of water in the pipe system, hydrants which provide a connection with the water in the mains for fighting fires, flushing streets etc, mains, sub-mains, and branch lines which carry the water to the streets, services which carry the water to the individual homes, etc. All these essentials and components of a water supply scheme are described in details in the subsequent chapters of this volume.