Editing Water tower (section)

== Design and construction ==
[[File:Shooters Hill.JPG|thumb|upright|[[Shooter's Hill]] water tower is a local landmark in [[London]], [[United Kingdom]]. Water towers are common around London suburbs.]]
[[File:Ross Barnett Reservoir water tower.jpg|thumb|upright|[[Ross Barnett Reservoir]] water tower in [[Mississippi]], an example of an older design of water tower]]

A variety of materials can be used to construct a typical water tower; steel and [[reinforced concrete|reinforced]] or [[prestressed concrete]] are most often used (with wood, [[fiberglass]], or brick also in use), incorporating an interior coating to protect the water from any effects from the lining material. The reservoir in the tower may be [[sphere|spherical]], [[Cylinder (geometry)|cylindrical]], or an [[ellipsoid]], with a minimum height of approximately {{convert|6|m|ft}} and a minimum of {{convert|4|m|ft|abbr=on}} in diameter.{{Citation needed|date=September 2011}} A standard water tower typically has a height of approximately {{convert|40|m|ft|abbr=on}}. <!-- and has an average of 2 million gallons. {{Citation needed|date=March 2011}} The largest wt in the world holds 1.2 million gallons, how can the average be 2 million??? -->

Pressurization occurs through the [[hydrostatic pressure]] of the elevation of water; for every {{convert|102|mm|in|3}} of elevation, it produces {{convert|1|kPa|psi|3|lk=on}} of pressure. {{convert|30|m|ft|2|abbr=on}} of elevation produces roughly {{convert|300|kPa|psi|3|abbr=on}}, which is enough pressure to operate and provide for most domestic water pressure and distribution system requirements.

The height of the tower provides the pressure for the water supply system, and it may be supplemented with a [[pump]]. The volume of the [[reservoir (water)|reservoir]] and [[diameter]] of the piping provide and sustain flow rate. However, relying on a pump to provide pressure is expensive; to keep up with varying demand, the pump would have to be sized to meet peak demands. During periods of low demand, [[jockey pump]]s are used to meet these lower water flow requirements. The water tower reduces the need for electrical consumption of cycling pumps and thus the need for an expensive pump control system, as this system would have to be sized sufficiently to give the same pressure at high flow rates.

Very high volumes and flow rates are needed when fighting fires. With a water tower present, pumps can be sized for average demand, not peak demand; the water tower can provide water pressure during the day and pumps will refill the water tower when demands are lower.

Using [[wireless sensor networks]] to monitor water levels inside the tower allows municipalities to automatically monitor and control pumps without installing and maintaining expensive data cables.