Rooftop Rainwater Harvesting

Rural Schools in Rajasthan
The Barefoot College Experience¹

Taken From Best Practices in Water Management-Case Studies from Rural India-2005 German Agro Action, 2005

Bunker Roy, Laxman Singh

Rainwater Harvesting (RWH) from roofs is a simple low cost technique that has been practiced for hundreds of years in the desert areas of India. For over two decades, the Barefoot College has provided drinking water in remote rural schools in 15 states for about 32 million people by collecting rainwater from rooftops of the schools and storing it in underground tanks. Barefoot College regards RWH is not only an alternative, but often as the only viable solution.

Rooftop Rainwater Harvesting is recognized as not only a simple and low cost traditional technique but as a permanent sweet drinking water source for school children in the rural areas. In remote villages where access to drinking water is a major problem, RWH structures serves two purposes:

• a source of potable water, especially during the dry season (4- 5 months)
• year-round water provision to improve hygiene, e.g. low-flush public toilets.

Applying local techniques, particularly in rural areas, directly benefits vulnerable groups in the society in several ways, such as:

• A direct effect of providing water in schools is evident in an increased attendance of children, particularly girls. Water scarcity and trekking long distances for collecting water, specially during dry periods increases the burden on women and girls, as a result education of the girl child is neglected. Collecting water for domestic use is usually the responsibility of women and girls. The hours they spend fetching water is time that is not available for childcare, productive activities and schooling.
• More children can concentrate on reading and writing in schools instead of spending hours fetching water.
• The availability of fresh drinking water and water for sanitation also reduces the incidence of waterborne diseases.
• Connecting rainwater harvesting structures to primary schools and other community places has an immediate capacity building effect and can be linked to environmental education programmes and education for improved hygiene and nutrition.

• By utilising other small-scale water harvesting systems in combination with rooftop water harvesting, irrigation water for vegetable gardens can also be nurtured.
• Access to safe drinking water in remote rural areas also enhances food security, nutrition, health and hygiene

In addition to this, the Barefoot College felt that working at the community level to resolve problems by using indigenous institutions and knowledge creates other positive outcome such as employment generation, participation and empowerment, capacity building of local organizations and communities, decentralized low-cost solutions and transparency and accountability.

Rain Water Harvesting ( RWH) Project for School

In 2003, a pilot project to harvest rainwater in 100 rural schools across 13 states was sanctioned by the Ministry of Water Resources, Government of India. This was the first time that an activity of this nature had been approved by the Ministry. The project was undertaken through 20 village Community Based Organizations (CBOs).

The aim of the project was to provide adequate water for drinking and sanitation by collecting rainwater from the roof tops of school buildings and storing this in underground water tanks. The RWH structures offer permanent rainwater storage of one million liters for drinking and sanitation.

The target group for the project were marginalized families including women and children who had to walk up to 10 km to collect water for their daily needs. This was particularly true for the children who often had to forego school in order to collect water.

Example of ifferent RWH designs used in Rajasthan. This technology can also be transferred to hilly areas.

Rainwater Harvesting Tank in School

The rural poor communities have addressed their own water needs by applying traditional knowledge, skills and using locally available raw materials to construct the rainwater harvesting tanks in schools and other community centers in the desert area of Rajasthan and in the Himalayan states.

The project successfully improved the quantity and quality of the collected rainwater by applying the principles of ecological engineering to traditional rainwater harvesting techniques. Additionally, it developed innovative filtration systems to reduce sedimentation (from collected water) and mitigate contamination (from stored water).

The Process of Construction of RWH

Why are underground tanks built for rainwater storage?

• Only an underground tank built in lime or local material can keep rainwater fresh till the next rainy season.
• This is a natural water storage device - providing warm water in winter and cold in summer.
• Underground tanks are more durable and maintenance free unlike the above ground level tank.

Selection of schools

Make a list of schools/community centers where drinking water is a problem due to:

• low seasonal rainfall in tropical zones
• high salinity in ground water
• high grade toxic mineral contamination
• lack of surface water source - pond, river, tanks
• bacterial presence in the existing surface water sources

Water Resource Mapping

• A water resource mapping (basic information of rainfall, existing water sources in the village) survey should be carried out in the beginning of the project
• Collect general infor-mation of all types of existing water sources (wells, hand pumps, piped water supply, ponds, rivers, streams, brooks etc.) in a village and its maintenance pattern
• Seasonal availability of drinking water from all the sources, quality of water, an approximate idea of the community demand for drinking water (total population) to be collected for generating reports on water resources
• Survey can be conducted by village people/teachers/ students, community contribution/ demand etc.

General Information

• Available area of rooftops of school/community building (in sq mt. /ft.)
• General gradient/ trend of  rooftop (flat  cement concrete roof and galvanized tin roof)
• Type of vegetation around the building/area
• Average annual rainfall data
• Drainage pattern of rooftop through drain pipes up to ground or open flow for direct runoff of rainwater.

Types of soil

• On the basis of the hardness of soil, generally soft and hard formations of soil are determined. The soil categories vary from sandy soil, clay mixed with lime  kankers
• Muram (white limes with small size gravel)
• Conglomeration of all
• Hard rocks (sedimentary/metamorphic)
• Weathered formation of hard rock

Location of Tank

• Tank should be close to the main building with an easy access for school children.
• The distance of tank from the building depends upon the area: 3 to 5 feet in hard subsurface in soft formation, distance should be more (10 ft.)
• Minimum length of pipes should be used to avoid chances of blockage. Large diameter pipes (at least 4 inches) are suggested to connect rooftop to tank.
• If subsurface is hard, do not try to dig a pit too deep. A tank can be raised 1/3rd above the ground surface and 2/3rd in the ground

Material for Construction

• Local building material (bricks/ stones)
• Lime/cement
• Water proofing powder (gypsum)
• Coarse sand
• Roofing material (Ferro cement/sandstone slabs) depends upon area.
• Transportation.

The shape of the tank depends upon the soil type. The basic traditional designs are rectangular and cylindrical (round).  A rectangular tank is good for hard rock area. The technique is simple: Dig a pit and cover it with a roof made of local stones. The rooftop tank can be used for holding classes in winter or as a stage for the school. Capacity: 42 cubic meters The cylindrical design is particularly suitable for the desert area. The knowledge of traditional and inexpensive construction technique of water structures is with the village community of the Thar Desert. It is incredible but true that local village masons and architects can construct cylindrical tanks and deep wells of upto 100 mts deep using locally available material.  These cylindrical tanks are a challenge to build even for trained civil engineers. Capacity: 39.6 cubic meters

We would like to thank German Agro Action for very kindly sharing the case studies for the portal.