Roof Rain Water Harvesting Structures (RRWHS) are used mainly for domestic purposes. They enable the rainwater that falls on the roofs of people’s houses to be collected in a range of different types of tank, either above or below ground level. Since the water that is collecting is generally free from soil pollution, it can be used for drinking after passing through a filter.
Once the rainfall falls on a roof with a gentle slope, it passes into a pipe and is directed through to the storage tanks. The pipework includes provisions for filtering out larger debris, grains of sand and other contaminants.
The size of the storage tanks can be adapted to the needs of the family, the average quantity of rainfall and the catchment area that surrounds it. Normally, a tank that holds 21,000 litres of water is enough to provide year-round drinking water for a family of 6 people, in a region with an average rainfall of 250mm.