Many communities rely on large storage tanks for their water supply system. Some tanks are made of glass fused to steel and have aluminum tank covers. Others are concrete, wood, galvanized steel or fiberglass. They often are lined with an interior coating or material approved for potable water. Most are built on site because of their size. Elevated water tanks, or water towers, need to be located where they will not be adversely affected by high winds, earthquakes or freezing temperatures. Open tanks, called cisterns, built with part of the tank in the ground and part above, cannot be used where flood water might enter. With proper maintenance, a large storage tank may last up to 100 years. Wooden tanks usually last 25 to 50 years. The lifespan of a concrete or fiberglass tank may reach 80 years, while the useful life of a metal tank ranges from 50 to 100 years.
Tanks that provide enough water for one residence are typically prebuilt. They may be made of coated metal with an inner lining, or they might be polyethylene. Polyethylene tanks often are colored to prevent light from reaching the water, thus reducing the formation of algae. The polyethylene is UV stabilized so it won't break down from exposure to ultraviolet rays. Polyethylene tanks are unaffected by soil chemicals and do not rust. Water barrels made of heavy-duty food-grade polyethylene can serve as storage tanks to keep an emergency supply of water.To store water that will be used strictly for irrigation or fighting fire, consider a concrete tank reinforced with steel. The tank is placed underground, with access provided by pipes extending to or above ground level. Requirements for other tanks placed underground vary. Some must be kept at least one-fourth full, while others suffer no harm by remaining in the ground empty.
Residential hot water tanks store a limited amount of water. The water is heated by electricity, propane, natural gas or the sun. Electric hot water tanks can be installed indoors, while natural gas and propane tanks require a special compartment that isolates the tank from living quarters and protects it from outdoor elements. Solar hot water tanks are often installed indoors but may be installed above the solar collector on the roof in mild climates.
Store water for emergency use in a cool, dry location unaffected by weather.
If well water is stored for more than 72 hours before use, boil or chemically treat it, following the Environmental Protection Agency recommendations or those of local authorities.