Local Knowledge About Storage (Tanks And Cisterns)

Cisterns are storage tanks for rainfall that has been collected from a roof or some other catchment area. Although usually located underground, cisterns may be placed at ground level or on elevated stands either outdoors or within buildings. If the captured rainwater comes from a clean source like a metal or tile roof, the water can be used for other purposes than irrigation. In these cases, the storage containers should be watertight, have smooth interior surfaces, enclosed lids, and be large enough to provide adequate storage. They should be fabricated from non-reactive materials such as reinforced concrete, galvanized steel, and plastic. Concrete blocks or wood are sometimes used, but these are difficult to keep watertight. A roof washer traps the first flow from the roof and channels this dirty water away from the cistern. After the first flow, the water from the rest of the rainfall flows to the cistern. The roof washer should have a capacity of about 10 gallons for each 1000 square feet of roof area. For outdoor use only, a simpler form of storage can be used.