Rainwater Harvesting for Domestic Water Supply in Kisii, Kenya

Abstract

Although the term Rainwater Harvesting includes the collection of natural precipitation from various prepared watersheds, I have only confined my discussion to the collection of precipitation from roof catchments. An assessment of the current water resources in Kisii Districthas been carried out and the position of Rainwater Harvesting as certained. The current state of some Rainwater Harvestinq systems has been examined. In general many of the systems are not well maintained and managed. It has been observed that storage tanks are under designed in some cases while many households cannot raise money to buy gutters and storage tanks. Water samples have been collected from these systems and other traditional sources and analysed. The results show that the rainwater is generally of good chemical and bacteriological quality; whereas the water from other traditional sources is not as good in many cases. Corrugated galvanized iron roofs were found to offer the best catchment. Run off is good from such roofs and they have no bad effects on water quality. Cheap but durable storage facilities like granary basket tanks have been recommended for small households, while the more expensive but strong concrete-block tanks or sub-surface tanks can be used for large volume storages for communities. Finally a comparative cost analysis between Rainwater Harvesting and other sources of water supply has been carried out. The results show that Rainwater Harvesting as a source of domestic water supply is feasible in the district since it hasan average annual rainfall or over 2000 mm. /Kir09