A simple water tank in a desert region
One of the main problems of the Thar Desert Region of southern Pakistan is a lack of a regular water supply. Poor women walk long distances to collect water, which is usually brackish, from deep borewells. Other problems are the shortage of fuelwood and the smoke created by cooking on open fires. The water problem can be alleviated to a large extent by providing families with a 2.4 m deep ‘urn-shaped’ tank below ground level with a capacity of 3,000 litres (nearly 700 gals). These will catch the monsoon rains and usually provide enough drinking water for families during six months of the dry season.
The internal shape of the tank enables it to be constructed using a very thin lining of cement /sand mortar.
How the tanks are constructed:
An urn-shaped hole is hand excavated to a depth of
2.4 m .
The faces of the hole are plastered with cement and water and then lined with a one and a half inch thickness of 1:4 cement/sand mortar.
After 12 hours the hole is filled with sand to enable slow curing. The sand iis then built up above the surface to form a turret.
The turret is plastered with a 75 mm thickness of mortar.
A 75 mm thick slab is formed around the tank to collect monsoon rainwater. (A small hole is made in the turret to channel water into the finished cistern).
The fill material is kept moist for 5 days and then removed
after 7 days.
Tank catchment 21 sq m
Storage capacity 3,000 litres
Costs in 2004:
Materials cost £12
Labour cost £7
Total cost £19