Rainwater harvesting is the principle of collecting and using precipitation (rain water) from a catchment surface.
Rainwater harvesting can be used for a number of applications including:
- Domestic use
- Use at schools, clinics and other public institutions
- Animal care
- Erosion control
- Flood control
- Aquifer replenishment.
In areas where there is reasonably good rainfall, Rainwater harvesting can be cost effective, easy to involve the beneficiary community in the setting up of the system as well as maintaining it. In general RWH does constitute simple and appropriate technology that does not require lots of technical input.
The main limitation of RWH is, the system’s dependence on the rainfall pattern of any particular area, and therefore, it is not always possible to depend solely on RWH for drinking water supply systems.
Mostly it is used as additional water supply source. On the other hand, for agricultural, and animal drinking water purposes, it is highly important and is considerably used.
Reasons to have rainwater harvesting as an alternative/additional water source are:
- Rainwater harvesting as a source of water supply is a system that can be addressed through community-based approaches in which ownership and sustainability of the system can easily be attained.
- Provided it is efficiently collected with the right technique, rainwater needs less work in terms of treatment to make it clean and potable.
- Current technological development in the use of tiles and corrugated iron sheet for roofing, fibreglass tanks for storage makes it an easy system to adopt.
- The shortage of water from other conventional sources such as wells, boreholes, springs rivers due to source depletion or drought makes it very necessary to resort to harvesting rainwater however intense or small the rainfall intensity is.
- Rainwater collection works best for schools and institutions with a large roof space and large storage tanks but is also effective for individual households or communal buildings where other sources are contaminated and it rains frequently.
- There should be a mechanism to prevent first rain run-off from entering the storage tank.
- In diarrhoeal outbreaks the storage tanks should be included in an emergency chlorination programme.
- There should be a cover on the rainwater collection tank to prevent contamination.