Water Cistern Construction

Water cisterns may be constructed of precast concrete, cast-in-place concrete, polyethylene or fiberglass. Cistern capacity, site topography, and the availability of the different types of cisterns will help determine the most economical type of water cistern for each application.

Usually, a local precast concrete company will manufacture each precast cistern “to order”, casting-in the appropriate size(s) of connection fittings, access(es), overflow(s) and vent(s). The cistern will then be shipped to and installed at its final location. Cast-in-place concrete contractors will also build cisterns “to order”; however, the cistern will be built in-place. Generally, cast-in-place concrete cisterns are most cost effective in capacities greater than 5000 gallons.

Polyethylene water cisterns can be cost effective for small capacities (less than 1500 gallons) and for applications in remote areas. Polyethylene cisterns are usually purchased locally; however, they are not made to order. Fiberglass cisterns are cost effective for large capacities (2000 gallon to 30,000 gallon) and can be made to order.

All cisterns must be vented to allow the free flow of air into and out of the cistern as the water level inside the cistern changes. The vent must extend to the surface and above the expected snow level. The vent opening must be turned down and must be screened with 24-mesh screen cloth to prevent the entry of insects, birds and other animals.

It is convenient to have a drainpipe and a“Direct-Bur” rated valve to empty the cistern, especially for cleaning) Such a drain can be installed if there is sufficient slope to the ground so the drainpipe daylights to the surface, as for instance on a hillside or bank of a nearby coulee or ravine. This pipe must slope slightly away from the cistern, and must be at least two foot in diameter. It must be set so the cistern will drain completely. The drain or overflow pipes should discharge over a drainage inlet or splash pad to prevent erosion and promote proper drainage away from the cistern. No drain or overflow may be connected directly to a sewer or a storm drain. All overflow pipes shall be located so that any discharge is visible. The overflow pipe shall open downward and be screened with 24-mesh non corrodable screen to prevent entry by insects, birds, and other animals.

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