This handbook on roofwater harvesting by the IRC International Water and Sanitation Centre has been written to assist NGO and government staff responsible for implementing domestic roofwater harvesting systems or programmes. It is also meant to serve as a source of material for rainwater harvesting associations preparing national design guidelines in local languages. Finally, it could be used by individual householders or masons literate in English to design single roofwater harvesting systems.
Domestic roofwater harvesting (DRWH) provides an additional source from which to meet local water needs. In recent years, DRWH systems have become cheaper and more predictable in performance. There is a better understanding of the way to mix DRWH with other water supply options, in which DRWH is usually used to provide full coverage in the wet season and partial coverage during the dry season as well as providing short-term security against the failure of other sources.
Interest in DRWH technology is reflected in the water policies of many developing countries, where it is now cited as a possible source of household water. Rainwater systems deliver water directly to the household, relieving the burden of water-carrying, particularly for women and children.
Part A is aimed at those with responsibility for choosing technology – for example managers of NGO and governmental water programmes. The rest of the handbook, Part B, is aimed at those implementing DRWH programmes and concentrates on which of the many forms of DRWH should be used in particular circumstances. The handbook is primarily focused on ‘low-cost’ DRWH in the ‘humid tropics’. It is deliberately specialised in geographical scope and target group, and quite prescriptive. The manual has illustrated practical examples from around the world, including India.