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Tuesday, 2-Jan-2007 13:23 Email | Share | Bookmark
A Water Reservior - Qazvin

The height of Dome is 50 meters
Cisterns are built by digging a hole in the ground to form a tank, with a single opening in the top to allow access. The walls of a cistern must be watertight in order to retain moisture. In the early 1900s cisterns were often made with a cement floor and dirt walls that had been coated in plaster. Modern-day cisterns may also be made from above-ground tanks, made of plastic. Cisterns usually have a lid covering their openings to prevent dirt, animals, insects, and other things from getting into the water.

Cisterns are commonly used in areas where water is scarce, either because it is rare or because it has been depleted due to heavy use. Early on the water was used for many purposes, including cooking, irrigation, and washing. Present day cisterns are often only used for irrigation, due to concerns over water quality. Cisterns today can also be outfitted with filters or other water purification methods when the water is meant for consumption. A few people leave their cisterns open to catch rain, or have more elaborate rain-catching systems. It is recommended in these cases to have a system that does not leave the water open to mosquitoes or algae, which are attracted to the water and then carry disease to nearby humans.

Some cisterns sit on the top of houses or on the ground higher than the house, and supply the running water needs for the house. They are often supplied not by rainwater harvesting, but by wells with electric pumps, or are filled by manual labor or by truck delivery. Very common throughout Brazil, for instance, they were traditionally made of concrete walls (much like the houses, themselves), with a similar concrete top (about 5 cm. thick), with a piece that can come out for water filling and be re-inserted to keep out debris and insects. Modern cisterns are manufactured of plastic (in Brazil with a characteristic bright blue color, round, in capacities of about 10k and 50k liters). These cisterns differ from water tanks in the sense that they are not completely enclosed and sealed with one form, and rather they have a lid made of the same material as the cistern, which is removable by the user.

To keep a clean water supply, the cisterns must be kept clean. It is recommended to inspect them regularly, keep them well-enclosed, and to occasionally empty them and clean them with an appropriate dilution of chlorine and to rinse them well. Well water must be inspected for contaminants coming from the ground source

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