Tiempo Climate Cyberlibrary

Rainwater Harvesting


About the Cyberlibrary

The Tiempo Climate Cyberlibrary was developed by Mick Kelly and Sarah Granich on behalf of the Stockholm Environment Institute and the International Institute for Environment and Development, with sponsorship from the Swedish International Development Cooperation Agency.

While every effort is made to ensure that information on this site, and on other sites that are referenced here, is accurate, no liability for loss or damage resulting from use of this information can be accepted.


The Intermediate Technology Development Group (ITDG) South Asia describes a rainwater harvesting project, designed to help people adapt to climate change in Sri Lanka and elsewhere.

ITDG is an international development agency with the vision "a world free of poverty and injustice in which technology is used to the benefit of all." ITDG South Asia currently works in the areas of energy, transport, manufacturing, agro-processing, disaster mitigation and natural resource management.

The Intermediate Technology Development Group (ITDG) South Asia began its rainwater harvesting pilot demonstration projects with financial assistance from the European Community and the Department of Agriculture in Sri Lanka. Support from the Fulmer Trust also allowed ITDG to strengthen its Livelihood Options for Disaster Risk Reduction (LODRR) Project by including work on rainwater harvesting. The LODRR project began in 2001 with assistance from the Conflict and Humanitarian Affairs Department of the Department for International Development in the United Kingdom. The LODRR project took a regional approach to the issue of disaster risk reduction. But at the individual country level, emphasis on implementing project components such as research, pilot demonstrations, capacity building and advocacy varied, depending on country needs.

Work on rainwater harvesting began in the Moneragala District of Sri Lanka. Pilot demonstration projects were then established in Usgala Village of Sooriyawewa Divisional Secretariat Division in Hambantota District, and in Mahameddawa Village in Nawagaththegama Divisional Secretariat Division in Puttalam District. All community participants were from economically marginalized sections of society. They had been subject to four or five seasons of crop failure resulting from bad climatic conditions. Drought was increasing in their areas. The unavailability of good quality water for drinking and other domestic purposes meant that diseases such as diarrhoea were common amongst community members.

The concept of rainwater harvesting

In Sri Lanka, drought occurs as a result of monsoon failure or reduced precipitation. Two thirds of Sri Lanka is categorized as a dry zone, and is prone to long dry spells and frequent droughts. Some parts of Sri Lanka's dry zone receive only 1000 to 1250 mm of rainfall per year. Most people in this area rely on irrigated paddy cultivation and subsistence farming, and drought affects the livelihoods of these people. An inability to store enough rainwater for use in the dry months means that many farmers have to survive with just one annual crop cycle. Water security is eroded and some villagers find themselves having to travel almost ten kilometres in search of potable water. Production decreases and incomes decline during drought periods. Project areas in other countries are also dry. For example, intervention areas in Pakistan have less than 400 mm of rainfall per year.

Rainwater harvesting tank

Above-ground rainwater harvesting tank

© ITDG South Asia

Rainwater harvesting is not a new idea for Sri Lankans - they have used the concept since ancient times. But modern rainwater harvesting technologies needed a 'testing time'. This was mainly due to technical deficiencies and a lack of awareness about the operation and maintenance of rainwater harvesting tanks. Focus was placed on developing technologies to suit the local conditions and on creating awareness among village level practitioners about best operational and maintenance practices. As a result of continuous effort to develop appropriate technologies, and with assistance from various government and non-government institutions, ITDG and its partner organizations were able to develop appropriate rainwater harvesting techniques.

In the past, many organizations built and promoted the use of underground tanks to harvest rainwater. But the proliferation of plant roots damaged the tanks making maintenance expensive. Promotion of the above-ground Ferro cement domestic rainwater harvesting tanks used by the ITDG projects successfully solved this problem. Many other institutions have promoted above-ground rainwater harvesting structures, but due to various deficiencies in their planning, construction and maintenance, most communities considered them less successful.

As evidence of this success, the initiatives taken by Care International and World Vision (as well as many other local non-government organizations) using ITDG pilot demonstration projects for their educational programmes can be cited. The National Disaster Management Center also implemented a special programme to provide tiles for all villagers with roofs thatched with cadjan leaves in Usgala Village, so that villagers could practice rainwater harvesting. The second Water and Sanitation Project of Puttalam District also constructed 100 rainwater harvesting tanks for the villagers of Mahameddawa. This provided all village households with rainwater harvesting tanks for use in their own houses. This initiative was a direct result of information sharing and advocacy activities carried out by the ITDG project with the help of the relevant authorities.

Livelihood improvements

A rainwater harvesting tank with a capacity of 5000 litres allows people to harvest a minimum of 25,000 litres of water in a normal year. Households in Mahameddawa Village used this water for eight months during the drought period. Without this water, villagers could have suffered severe hardship, especially in a drought year like 2001 when they might have had to have walked two or three kilometres to fetch water. Ms Jayasingha of Mahameddawa Village stated that "thanks to rainwater harvesting tanks, now we can live with peace of mind. Even though we may not have anything to eat due to the drought, we know that we have at least good quality water at our doorstep to drink."

Rainwater harvesting

Rainwater harvesting

© ITDG South Asia

With improvements introduced by ITDG, Sri Lanka now promotes the construction of aboveground Ferro cement tanks with a capacity of 7500 litres. Rainwater harvesting is also used to support village livelihood options based on agriculture. Simple drip irrigation systems are fitted to above-ground rainwater harvesting tanks. The pressure created from the water in the tank is all that is needed for irrigation - pumps and other mechanical devices used for drip irrigation elsewhere are not necessary. Drip irrigation supports the growth of crops for which there is a high market demand. Another simpler type of drip irrigation system - the bucket kit method - is also used to cultivate high value crops.

'Run off rainwater harvesting' is mainly used for agricultural purposes. This method collects free flowing groundwater in tanks with a capacity of 5000 to 12,000 litres. Some 30 to 35 perennial crops can then be grown in half an acre of land. To maximize the efficient use of available water, 'pitcher (pot) irrigation' is used coupled with mulching and other best agricultural practices. A 7500 litre aboveground domestic water tank costs around 20,000 Rupees (about US$200). A run off agricultural rainwater harvesting tank with a capacity of 10,000 litres will cost around 12,000 to 15,000 Rupees (US$120 to US$150), depending on whether or not construction materials are available locally. In all instances, the community contributed around 45 to 50 per cent of the costs. ITDG and its partner organizations always emphasize the importance of community contributions, as this gives a sense of ownership to the project participants.

The approach

The technology itself is a package comprising 'hardware' and 'software'. The 'hardware' includes the technology and the physical project components. The 'software' includes community mobilization, participatory development of the technology itself, and capacity building for the use of the technologies. The contribution and participation of communities is an important component of project sustainability. Giving training on the technology to the local masons and providing knowledge on the operation and maintenance of the technology to other community members enhances the quality of the water they will receive.

Large-scale replication

Replication of the project by other agencies started before the project was completed. Replication of the total approach and its various components was done by government agencies in Sri Lanka and Pakistan, international donors such as the Disaster Preparedness Programme of the European Commission Humanitarian Office - South Asia, and international non-governmental organizations such as the United Nations Development Programme, OXFAM Pakistan, Plan International Sri Lanka, and Care International Sri Lanka.

Further information
Rohana Weragoda, ITDG South Asia, No. 5 Lionel Edirisinghe Mawatha, Kirulapone, Colombo 5, Sri Lanka. Fax: +94 11 2 856188. Email: rohanaw@itdg.slt.lk. Web: www.itdg.org.

On the Web
The Tiempo Climate Cyberlibrary presents a listing of websites covering rainwater harvesting.

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Updated: May 15th 2015