by Murray Burt.
In rural areas, the main water sources are normally groundwater borewells or surface water, rivers and lakes. However, an often overlooked, easily accessible and sustainable source of safe drinking water during the wet season is rain. In tropical and sub-tropical climates the quantity of water collected from rainfall can be substantial.
There are clear advantages to rainwater harvesting at home:
- improved health
- easy access
- low cost
- it is easy to manage.
Traditional rainwater harvesting
Traditional methods of rainwater harvesting used in Uganda and Sri Lanka include rainwater collection from trees, using banana leaves or stems as temporary gutters. Up to 200 litres may be collected from a large tree in a single storm.
Rooftop rainwater harvesting
Very low cost domestic rainwater harvesting systems can be easily installed on most corrugated iron or clay tile rooftops in rural and urban areas, using various forms of guttering, first flush diverters and plastic or ferro-cement tanks for collection and storage.
Very low cost rooftop rainwater harvesting using corrugated iron roof, hard plastic pipes and ferrocement jars for storage at a home in Cambodia. Photo: Murray Burt/Tearfund
Rainwater harvesting without rooftops
However, in some rural areas most people live in simple thatched roof structures, which are not suitable for traditional rain - water harvesting. Tearfund has therefore researched and tested an innovative and simple ‘ultra low cost’ way of harvesting rainwater without using rooftops.
Rainwater harvesting off the roof of a latrine in Cambodia, using an old soft drink bottle, hard plastic pipe, corrugated iron and a brick storage tank. This concept is especially useful as it provides water for hand washing right at the door of the latrine. Photo: Murray Burt/Tearfund
Using plastic sheeting
Ultra low cost rainwater harvesting system in Southern Sudan, using a plastic sheet, wooden poles and plastic jerry can. Photo: Murray Burt/Tearfund
In many populations on the move, especially in emergency and postemergency situations, plastic sheeting is a basic commodity that many households own. It is either given through distributions at refugee camps or camps for internally displaced persons, or purchased on the local market. Plastic sheets are used for many purposes including as shelter for homes or shops. They can also be used for rainwater harvesting. Calculations based on rainfall data from Colombo, Sri Lanka, show there would be an average daily yield of more than 60 litres over six months of the year from rainwater harvesting using an 8m² plastic sheet for collection.
Designing your own rainwater harvesting system
Using plastic sheeting is one option for rainwater harvesting without using a roof. Other locally available materials can also be successfully used, such as single corrugated iron sheets and cloth.
There are no rules for construction. Think of new ideas using whatever materials you have available to catch and collect the rainwater. The principle is always the same:
Catch the rainwater on a clean surface before it hits the ground, and channel into a clean collection container.
It is easy to scale up rainwater harvesting systems. In emergency situations, rainwater harvesting can be made available to all and can even contribute as a significant water source in large communities and camps. Remember to promote good hygiene at the same time, making sure that each part of the system is clean. Cover the water container and make sure the stored water is not removed by dipping hands or scooping using dirty cups or other dirty items. Rainwater which has been stored for a long period may require disinfection. Protect water containers with a screen to stop mosquitoes breeding and keep out sunlight to prevent the growth of algae.
DFID WASH Programme Manager
PO Box 76184-00508
What people said
‘Rainwater tastes clean; it has no smell.’ (Agul Tour, 19 years, at Omdurman Market demonstration)
‘We are coming out of war … we are happy to learn how to harvest water … we are open to new ideas.’ (Marc Tuc, 60 years)
‘I tasted the water at the church. It was good – it is the kind of water that does not make one sick.’ (Nyibol Ngor, 17 years)
‘The community is happy about rainwater harvesting as they now will have more water to use, especially during the dry season.’ (Daniel Aleu, 25 years)