Rain Water Harvesting


“If there is a 3rd World war, it is said, the war will be for drinking water.”

Water resources are becoming scanty. Rain water harvesting is The solution to  his problem. We are specialized in both long term and short term Rain Water Harvesting projects. Roof Top Rain Water Harvesting is the short term and ground water recharging is the long term plan.

Rain Water Harvesting is the main programme under this sector. To assure drinking water to all, harvesting the abundant rain water is the ideal mechanism. We have constructed thousands of Rain Water Harvesting systems in various parts of country. Our projects are in state of Kerala, Andhra Pradesh, Karnataka and Tamilnadu.

Rain Water Harvesting

Kerala gets an average of 250 to 300 cm rainfall, annually. Due to the steep terrain, the major chunk of the rainwater falling reaches the oceans within a span of 48 hours. This rainwater if harvested, can be used for drinking and cooking purposes during the stringent summers. Rainwater is harvested from the rooftops of buildings by channeling through chutes then passing through layers of sand, gravel and activated carbon filters,  before it gets collected in the harvesting tank. It is a proven fact that rainwater thus collected and kept without contact with air or sunlight can be retained pure for a year. Thus collecting rainwater at every household is the most economical and feasible remedy for shortage of drinking water.

For an individual, per day, 20 liters of water is needed for cooking and drinking purposes. Thus for a family of 5, around 100 liters of water is needed per day. Hence 10,000 liters of rainwater can suffice the need for drinking water for a family of 5 for a period of three months. In a place, which gets an average 200 cm of rainwater annually, a surface area of 8 sq.m is enough to fill a harvesting tank of capacity 10,000 liters in 8 days. The cost per liter of Rain Water Harvested in a ferro-cement tank is around 6 to 7 rupees. Moreover, the technology is Eco-friendly. The cost is further reduced if the tank is built underground.

“Varsha” – Rainwater Harvesting Scheme

The project was undertaken by us under the aegis of Kerala Water Authority (KWA), Govt. of Kerala envisaging construction of ferro cement Rain Water Harvesting Systems in the Districts of Ernakulam, Alleppy, Kottayam, Thiruvananthapuram and Pathanamthitta. through this project we have covered more than 30,000 families. introduction of a new technology in Government sector-ferro cement technology-is one of the indirect advantages of the project. we have constructed Rain Water Harvesting systems in more than 500 Governemnt institutions and schools. the largest single rainwater system we have constructed is having 200000 ltr capacity

Other water management programmes we implement are WGDP (Western Ghatt Development Program), NWDPRA (National Water Development Project under Rain Fed Areas) and RAINS (Rain Water Harvesting Awareness Implementation Network System), Jalanidhi of KRWSA under the world bank project


  • Kerala Rural Water Supply & Sanitation Agency (KRWSA) – Govt.of Kerala
  • Kerala Water Authority (KWA) – Govt.of Kerala
  • Western Ghats Development Programme (WGDP) – Govt.of India
  • Local Self Government bodies
  • Department of Water Supply – Govt.of India

Watershed Management

The Andhyodaya’s one of the servicing area is the implementation of the watershed and its management. We have constructed many watersheds effectively, an example is Assamnnur Panchayat. A watershed is a basin like landform defined by peaks which are connected by ridges that descend into lower elevations and small valleys. It carries rainwater falling on it drop by drop and channels it into soil, rivulets and streams flowing into large rivers and in due course sea.

Watershed Management is the the process of creating and implementing plans, programs, and projects to sustain and enhance Watershed functions that affect the plant, animal and human communities within a satershed boundary. Features of a Watershed that agencies seek to manage include water supply, water quality, drainage, storm water runoff, water rights and the overall planning and utilization of  Watersheds.


Rain Water Harvesting is the technique of collection and storage of rain water at surface or in sub-surface aquifer, before it is lost as surface run off. The augmented resource can be harvested in the time of need. Artificial recharge to ground water is a process by which the ground water reservoir is augmented at a rate exceeding that under natural conditions of replenishment..


  • To overcome the inadequacy of surface water to meet our demands.
  • To arrest decline in ground water levels.
  • To enhance availability of ground water at specific place and time and utilize rain water for sustainable development.
  • To increase infiltration of rain water in the subsoil which has decreased drastically in urban areas due to paving of open area.
  • To improve ground water quality by dilution.
  • To increase agriculture production.
  • To improve ecology of the area by increase in vegetation cover etc.


  • The cost of recharge to sub-surface reservoir is lower than surface reservoirs.
  • The aquifer serves as a distribution system also.
  • No land is wasted for storage purpose and no population displacement is involved.
  • Ground water is not directly exposed to evaporation and pollution.
  • Storing water under ground is environment friendly.
  • It increases the productivity of aquifer.
  • It reduces flood hazards.
  • Effects rise in ground water levels.
  • Mitigates effects of drought.
  • Reduces soil erosion.


The important aspects to be looked into for designing a RainWater Harvesting system to augment ground water resources are:-

  • Hydrogeology of the area including nature and extent of aquifer, soil cover, topography, depth to water level and chemical quality of ground water.
  • The availability of source water, one of the prime requisite for ground water recharge, basically assessed in terms of non-committed surplus monsoon runoff.
  • Area contributing run off like area available, land use pattern, industrial, residential, green belt, paved areas, rooftop area etc.
  • Hydrometerological characters like rainfall duration, general pattern and
  • intensity of rainfall.


  • Where ground water levels are declining on regular basis.
  • Where substantial amount of aquifer has been de-saturated.
  • Where availability of ground water id inadequate in lean months.
  • Where due to rapid urbanization, infiltration of rain water into subsoil has decreased drastically and recharging of ground water has diminished.


The methods of ground water recharge mainly are:

Urban Areas

Roof Top Rain Water / storm run off harvesting through

  • Recharge Pit
  • Recharge Trench
  • Tubewell
  • Recharge Well

Rural Areas

Rain Water Harvesting through

  • Gully Plug
  • Contour Bund
  • Gabion Structure
  • Percolation tank
  • Check Dam / Cement Plug / Nala Bund
  • Recharge shaft
  • Dugwell Recharge
  • Groundwater Dams / Subsurface Dyke We started implementing ‘VARSHA’ a Kerala Govt. program of Roof Top Rain Water Harvesting using ” Ferrocement technologies” in the year 2002 by now we have covered nearly 30,000 families in the state.


This technology is an economical, efficient, and easily adoptable one depending on the topography of the location where it is implemented. The word ‘Ferro’ is coined from Ferrous (meaning Iron). This technology took its birth in the year 1848 in the hands of Joseph Louis Lambert, a French Engineer. He designed a boat by cement-plastering both sides of thin iron wiremesh. Being found the boat strong and useful, this technology perpetuated as Ferro Cement technology. The exercise of this technology has now become very common. Using this discipline, houses, wardrobes, tables and chairs, water tanks etc. are being constructed now.

Ferro Cement technology is presently being widely used in the construction of water tanks. Majority of the tanks built using this principle is circular in shape. The average thickness of the wall will vary between 3cm and 10cm. The wiremesh used in these structures distribute the hydro pressure to the entire structure thereby reducing the weight. This system has set its root in Kerala also. In Kerala, ferro cement tanks are used mainly for Roof Top RainWater Harvesting.

The Andhyodaya is one of the pioneers in the country in implementing organized Roof Top Rain Water Harvesting Programme. ‘VARSHA’, a Kerala G ovt.sponsored Programme was a success only because of the intervention of our organization. Under ‘VARSHA’ rooftop Rain Water Harvesting in Ferro cement tanks was implemented in 4 districts of the state viz, Ernakulam, Alappuzha, Kottayam and Trivandrum. This project was launched by the state Govt. in collaboration with Kerala Water Authority implemented by our organization in the year 2002. Ferro cement tank of 5000 and 10000 liter capacities were constructed under the programme for the benefit of Below Poverty Line (BPL) families. These Rooftop Rain Water Harvesting Ferro cement systems have a capacity to harvest about 3 cores liters of Rain Water during rainy week. That means, in a rainy season, these systems can harvest a minimum of 15 cores litters of Rain Water. Besides VARSHA, we are also undertaking rooftop Rain Water Harvesting for the Govt. buildings and institutions.

We have a trained and effective infrastructure to take up any size of Rain Water Harvesting projects anywhere in the World. Comprising of Engineers, Co-coordinators, Supervisors and Technicians.

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