Rainwater harvesting in South Asia

Author: Suma Mathews and S. Sreekumar, SEUF, December 2005

Quality assurance: Jo Smet and Kristof Bostoen

History

In Hindu mythology water is considered as sustainer and purifier. In ancient days water was treated with reverence, with mechanisms to preserve and judicial consumption being practised in most parts of India. The early Hindu texts written around 800-600 B.C. reveal some knowledge of hydrological relationships (the philosophical reflections of Vedas and Upanishads). Evidence of water supply for domestic use and irrigation with water harvesting systems can be found in Kautilya’s Arthasatra written in 3rd century B.C. Records show that people knew about rainfall regimes, soil types and irrigation techniques, dams, canals, tanks and embankments. They developed a range of techniques to harvest every possible form of water. These included technology for spring water systems with split bamboo pipes, catchments basins and traditional water harvesting tanks such as tankas and kundis. Traditional techniques varied from state to state and even region to region because of diverse patterns of monsoon and terrains of the country. In the hills and areas with high rainfall, rooftop collection and storage by constructing dug-cum-embankment types of structure were used. In the foothills, the flow of springs and streams were arrested and stored. And in the desserts surface rainwater collection was preferred. From those early days effective systems of water management had been established and operated by small communities in many regions of the country.

Water Situation in India

India is blessed with good quality rainwater, average 1220 mm/year or about 400 million-hectare meters  (= 4,000 billion m3) of rain annually over a geographical area of  3,290,000 km2. If rainwater is properly conserved it can be used to fulfil all water needs in the country.

Nowadays, 85% of the drinking water in India originates from surface and groundwater. However, massive exploitation of groundwater has led to lowering of water tables and depletion of aquifers. In 1996, there were 65,000 villages in India without water sources. Changes in life style increase water demands, and consumption, population growth etc. make effective rainwater harvesting a necessity.

See also the WELL Global Domestic Rainwater Harvesting Fact Sheet: http://www.lboro.ac.uk/well/resources/fact-sheets/fact-sheets-htm/drh.htm

Frequent droughts in Southern Africa are threatening availability of food and food security in the region.  Much of the response by governments of the countries in this region have tended to be on developing water resources mainly through construction of dams and irrigation schemes. This option often involves water transfer from one catchment to another, which besides being expensive to implement and to maintain, has a negative effect on the environment. One answer to the current crisis might lie in the promotion of rainwater harvesting techniques, especially as a source of water for domestic use and for agriculture between dry spells.

The Water Situation In Kerala

Kerala, the most southern state in India, has 44 rivers, 29 fresh water lakes and perennial springs and the highest well density in the world (250 open wells/km2). Despite the fact that most of these sources of water are used for piped water supply schemes, Kerala is facing acute water scarcity in summer months. The density of population in this state is very high. In many coastal areas saltwater intrusion renders the groundwater brackish and therefore unsuitable for drinking. Although Kerala gets an average rainfall of 3,000mm/year, most during monsoon, and because of geographical conditions, most runs off to the sea within a short time. The improper management of storm water causes floods and droughts every year in the country.  Harvesting and conserving this rainwater for domestic and small-scale irrigation use is the most promising practice to solve these problems. Rainwater harvesting is particularly important in arid and semi arid regions, in remote isolated habitations in difficult terrains, and where chemical contamination makes existing water sources unfit for domestic water use.

 Thousands of Indian villages still do not have a local potable water source within one kilometre or groundwater within 15 meters. These villages are treated as problem villages. In many parts of India water quality is very poor due to chemical and bacteriological contamination, presence of germs etc.

Reservations against Rainwater

People in many parts of the world are reluctant to use rainwater as drinking water for a variety of reasons. For instance traditionally in Kerala people believe that only well water is good for drinking because it tastes good. They also believe that water in wells should get sunlight. Stored water is not pure water, and hence people in Kerala prefer open contaminated wells. Rainwater harvesting is not viewed as a modern technique. Furthermore, rats (may cause leptospirosis) and droppings of birds on the roof may raise fear and doubts on the water quality.

Therefore, awareness raising of the advantages of rainwater harvesting is needed to create demand and to motivate people to get them involved in the whole process. Rainwater harvesting can be most successful in areas facing water problems due to scarcity and contamination.

Rainwater Harvesting in Kerala

The collection and storage of rainwater can be in man-made structures or natural depressions. Catchment areas can be rooftops, compounds, rocky surfaces or hill tops. Rooftop harvesting structures on islands like Lakshadeep and in the North Eastern Provinces are very successful.

The most popular means of collecting rainwater for individual households is from the roof tops. Another method of harvesting rainwater is collection of runoff rainwater in abandoned dug wells, recharge pits and recharge trenches. These methods are for groundwater recharge, which eventually helps in raising the water table. For instance in Chellanum Grama Panchayat in Kerala roof water is harvested around the dug wells to recharge the well and reduce the salinity intrusion.

Rainwater can be collected from large roof surface areas to underground sumps. From the sumps water can be pumped to overhead tanks. After proper water treatment this drinking water can be supplied to institutions. Rainwater from clusters of households can also be collected in large storage tanks and after suitable treatment the drinking water can be distributed.

The Kerala government is implementing such projects in Varsha Scheme. Varsha is a project of Kerala Water Authority to construct rainwater harvesting structures for low income families. The beneficiaries contribute 10% and the government 90% of the total cost. This project is implemented by experienced agencies.

Nation-wide Initiatives

The Union Ministry for Urban Development in India has asked the State Governments to take legislative steps to ensure maximum possible collection of rainwater. Many State Governments have already taken steps in this direction, such as Tamil Nadu, Karnataka and Kerala.  Legislations and amendments to building rules have been passed in different States in India since 2000. Rainwater harvesting was made mandatory in all new buildings in Kerala, Tamil Nadu, Karnataka, Uttar Pradesh, Andhra Pradesh, Haryana, Gujarat, and Rajasthan. There is no unified specification in these States about the plot size or area of building etc. and differences exist between States in enforcement of rules.

The Local Self Government institutions are asked to adhere to rainwater harvesting rules while issuing building permits.  Special rules are issued to construct rainwater harvesting structures in houses,  building complexes, schools and government buildings depending on the plinth area of the buildings.

The Government declared 2004 as the “Year for Rainwater Harvesting”.  With the objective of promoting rainwater harvesting, the Kerala Government has set up a Rain Centre under the nodal agency- Kerala Rural Water Supply and Sanitation Agency. They are functioning as resource centre, coordinating the Government and non-government agencies (NGOs) as well as conducting information and education campaigns.

Rain Centres have been established in Chennai , Meerut and Trissur by the initiative of NGOs to demonstrate different working models and to provide assistance to the public for designing rainwater harvesting, locating masons, materials etc.

Only the 10,000 litres rainwater harvesting tank designs have been approved by the Government Departments. Larger tanks are commonly constructed but no standard designs have been approved.

The relationship between health and water quality should be imparted to the community through water literacy campaigns. Health and hygiene promotion should be an integral part since behavioural changes associated with water use, proper maintenance of systems and sustainability of facilities and behaviour change are the key issues. In short, “water should be everybody's business!"

References

1. Anil Agarwal, Sunita Narain and Indira Khurana (2001). Making water everybody’s,  Business  Centre for Science and Environment (CSE)
2. RGNDWM (1998) Handbook on Rain Water Harvesting
3.  Dwijen Mallick (2001) Safe Drop - the safer sources. NGO Forum for Drinking Water Supply and Sanitation, Dhaka, Bangladesh
4. Socio Economic Unit Foundation, Training handouts Thiruvanthapuram, Kerala,  India
5. Anil Agarwal and Sunitha Narain (2001)  Dying wisdom Centre for Science and Environment (CSE), New Delhi, India
6. CSE-Rainwater Harvesting Organisation: http://www.rainwaterharvesting.org/ and http://www.cseindia.org/ 

This Region Specific Annex has been prepared by Suma Mathews and S Sreekumar from the Socio-Economic Unit Foundation (SEUF), Kerala, India

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