Rainwater harvesting is an extremely old method, used in many ancient civilisations, which involves collecting and storing rainwater for human use from rooftops, land surfaces or rock catchments. The collected rainwater can be used for household drinking water, agriculture, washing, or a backup supply of water during dry seasons or breakdowns of other water supply sources.
Interest in the method has been reviving in the mid-20th century due to many factors such as:
· Lack of ground and surface water availability and then poor quality of that water
· More and more pressure on water resources with growing population
· Use of materials like tile and iron roofs instead of grass/thatch, which makes it easier to direct the rainwater
· More effective and cost-friendly tank designs coming out on the market
Storage systems can range in complexity, from simple rain barrels to more complex systems such as pumps or larger tanks. The recommendation is to use “dry systems”, which are systems that do not hold any water in pipes after raining stops, to prevent the creation of breeding grounds for mosquitos and other insects. Wire mesh can be built on top of the pipes to prevent debris from entering the pipes and tank.
If rainwater is used for drinking water, it should still go through a treatment method such as flocculation, settlement, or chlorination.
· Convenience as water can be provided near the point where water is needed, saving time for women or water fetchers, or eliminating the need for complex and costly distribution systems
· Can complement other water sources, relieving pressure on limited water supplies, or during natural disasters.
· People have full control over their own catchment systems, improving household water security and minimizing operation and maintenance problems.
· Technology is very simple to construct, install, and operate, based on traditional methods
· Rainwater is free
· Rainwater often is usually superior in physical and chemical properties to surface and groundwater which may be contaminated.
· Since rainwater systems typically use existing structures like rooftops, they have few environmental impacts compared to other developments like dams or piped networks.
· Rainwater for domestic use emphasizes small-scale, community-based, self-help development.
Unfortunately, rainwater harvesting depends on the weather. During the wet seasons, rainwater harvesting will produce lots of water, but during dry seasons, another source of water is needed. Regular maintenance and cleaning are still required, storage tanks if not properly covered and maintained could become breeding grounds for mosquitos.
Source: Center for Affordable Water and Sanitation Technology (CAWST), Introduction to Household Rainwater Harvesting, November 2011 Manual, licensed under CC BY-SA 4.0
These are several examples of ways to self-supply water. Having a convenient supply of water means less stress in worrying about where water will come from, less wasted time water fetching and more time for productivity. Research has shown that water consumption increases two or three times when a water source is available on site, with the additional consumption likely to have been used for hygiene purposes and therefore able to increase health.