Water Tower

A water tower is an elevated structure that supports a water tank at a height sufficient to pressurize a water distribution system and to hold an emergency reserve for firefighting. The tower relies on hydrostatic pressure, roughly one kilopascal of pressure for every 102 millimeters of height, so a typical forty-meter tower produces about three hundred kilopascals, enough for most domestic water systems, and because gravity does the work, a water tower can keep delivering water even during a power outage, though pumps are still needed to refill it. Elevated water storage existed in antiquity, but the modern water tower emerged in the mid-nineteenth century as steam pumping and stronger pressure-rated pipes became available; early British installations used tall standpipes to relieve pressure and measure flow, and storage tanks were added to these structures by the late nineteenth century to meet growing urban water demand.