Water tank



Water tanks are storage containers for water, these tanks are usually storing water for human consumption. The need for water tanks is as old as civilized man. Water tanks provide for the storage of drinking water potable, irrigation agriculture, fire suppression, agricultural farming and livestock, chemical manufacturing, food preparation and many other applications.

Various materials are used for constructing water tanks: plastic, polyethylene, polypropylene, fiberglass, concrete, steel (welded or bolted, carbon or stainless). Earthen ponds designed for water storage are also often referred to as tanks.

The water tanks in the picture are located in a municipal water system: "Hydro-pneumatic water tank", an AWWA lined carbon steel pressure vessel is designed to provide pressurized water to the distribution system. "Chemical contact tanks" of FDA and NSF polyethylene construction allow retention time for water and chemicals to be in contact and mix. "Ground water tank" is made of lined carbon steel, it may receive water from well or surface water allowing a large volume of water to be placed in inventory and used during peak demand cycles. Very large water tanks may be "Elevated Water Tanks", by elevating the water tank, the increased elevation creates a distribution pressure at the tank outlet of 1 psi per 2.31 feet of elevation, thus a tank elevated to 70 feet creates about 30 psi of discharge pressure, 30 psi is sufficient for most house hold requirements.

The profile of water tanks begins with the application parameters, thus the type of material used and the design of the tank was dictated by these variables:

1. Location of the water tank (indoors, outdoors, above ground or underground)

2. Volume of water tank will need to hold

3. What the water will be used for.

4. Temperature of area where water will be stored, concern for freezing.

5. Pressure required to deliver water

6. How is the water to be delivered to the water tank.

7. Wind and Earthquake design considerations allow water tanks to survive seismic and high wind events.

Throughout history, wood, ceramic and stone have been used as water tanks. These were all naturally occurring and manmade and some tanks are still in service.

The Indus Valley Civilization (3000–1500 BCE) made use of granaries and water tanks. Medieval castles needed water tanks for the defenders to withstand a siege. A wooden water tank found at the Año Nuevo State Reserve (California) was restored to functionality after being found completely overgrown with ivy. It had been built in 1884.

Vertical cylindrical dome top tanks may hold from fifty gallons to several million gallons. Horizontal cylindrical tanks are typically used for transport; this low-profile transport storage creates a low center of gravity helping to maintain equilibrium for the transport vehicle, trailer or truck. Hydro-pneumatic tanks are typically horizontal pressurized storage tanks. Pressurizing this reservoir of water creates a surge free delivery of stored water into the distribution system.

There are many custom configurations that include various rectangular cube shaped tanks, cone bottom and special shapes for specific design requirements.

A functional water tank/container should do no harm to the water. Water is susceptible to a number of ambient negative influences, including bacteria, viruses, algae, changes in pH, and accumulation of minerals. Correctly designed water tank systems work to mitigate these negative effects.

Articles and specifications for Water Tank applications and design considerations: American Water Works Association The AWWA is a reservoir off water tank knowledge; the association provides specifications for a variety of water storage tank applications as well as design. The AWWA's site provides scientific resources with which the reader will be able to develop an informed perspective on which to make decisions regarding their water tank requirements.

NSF International writes standards, inspects and confirms that manufactured products that come into contact with air, food, consumer goods and water are suitable for human consumption.

The Food and Drug Administration approves materials for use in storing water and food materials. Consult the Code of Federal Register for more details on water tanks.

Other uses
Space flight simulator Flight simulators use elaborate water tanks for the simulation of weightlessness. Water tanks fabricated to resemble space craft interiors are suspended in large swimming pool like environments, giving astronauts the feeling approximating zero gravity.

The Airline industry uses elaborate water tanks to simulate, aircraft emergency water landings and the performance of the airplane upon entry to the water.