Rainwater can be collected from the rooftops of houses, schools or other buildings. Roofs with galvanized iron sheets work best for collection, but tiles and sheets are also acceptable. Applicable above 200 mm precipitation per annum, but long dry periods will necessitate an alternative water source. Risk of contamination with suspended solids.
Usually, roofs are already in place. If not, investment is needed for adequate roofing. If yes, these costs (6-12 USD/m2) might be prohibitive for household(s). Additional costs may occur in the form of household treatment or storage/conveyance facility construction.
Optimal decentralized method; can be managed at (shared) household-level. More facilities may prompt establishment of local water committee to optimize managing. Resilience can be improved by organized - professionalized, regional-level - monitoring. Proper (micro-)credit scheme is essential for local dissemination.
Good solution if sufficient rainfall and no other good quality water sources. Often insufficient for year-round consumption. This may require alternative water source development. Water quality might be problematic: roof corroded or contaminated with dust, leaves, insects, bird droppings, etc.
Maintenance is simple but requires regular and careful attention. Roof should be frequently cleaned, ideally after every dry period exceeding one month. The initial precipitation is not for storage, but for flush-cleaning system. Large-scale roof repairs can be executed by local craftsmen.
Requires an awareness-raising campaign to acquaint potential users with this solution. Periodically, people might use unimproved sources if water yield is insufficient. Mostly used for drinking water only, because of low yield. In schools often used for hygiene and gardening.
No relevant remarks for Rooftop rainwater harvesting.