What is Water supply system?
A '''water supply system''' or 'water supply network' is an engineering system which provides a supply of [[fresh water|water]]. A water supply system typically includes: # A supply of pure water for drinking and other uses. That is why almost all large cities are are on or near to rivers. However, water can be moved distances along pipes or [[aquifer]]s. # Water storage facilities such as [[reservoirs]], [[water tank]]s, or [[water tower]]s are necessary. Smaller water systems may store the water in [[cistern]]s or pressure vessels. Tall buildings may need to store water locally in pressure vessels in order for the water to reach the upper floors. # Water pressurizing by such as [[pumping station]]s are usually needed at the outlet of underground or above ground reservoirs or cisterns (if gravity flow is impractical). # A pipe network for distribution of water to the consumers (which may be private houses or industrial, commercial or institution establishments) and other usage points (such as [[fire hydrant]]s). The second part of the system is dealing with the [[sewage]] and waste water which is eventually put back or comes back into the system.<ref> Crittenden, John C. et al (eds) 2005. ''Water treatment: principles and design''. 2nd ed, Hoboken, NJ. Wiley. ISBN 0-471-11018-3</ref> If this' waste water' is not purified, [[cholera]] and [[typhoid]] [[epidemics]] will occur, and still do occur, in cities where the water engineering has not kept pace with [[population growth|population increase]].<ref>Neumann H. 1981. Bacteriological safety of hot tap water in developing countries. ''Public Health Rep''. '''84''':812-814.</ref> # [[Water purification]] facilities. After any solids in the water have settled out, the water is aerated. This is done by running it slowly over an aerated pebble bed, or through a sand bed. The oxygen in the water kills off the bacteria which are [[anaerobic]]. Sometimes poisonous [[red algae]] survive, and if so these are killed by adding [[chlorine]] to the water. The water is the