Eco Sustainable Village

Links to catching rain water

Catching the rain

Low-cost rainwater harvesting is ideal for poor families. SHREE PADRE on one such experiment in rural Karnataka.

NARAYANA is a poor radio mechanic who lives in Vittal, Karnataka, and has a four-member family. They live in Punacha, a village 12 km away. Their three-room house was built five years ago on five cents of land allotted by the Government.

Though 22 such sites were allotted in this locality, only two families went ahead with constructing their houses. As there is no water connection nearby, water had to be fetched from far-off.

Fortunately for Narayana, his neighbour had permitted him to draw water from his well. But there was a hitch. The well is nearly a furlong away. During the rainy season, the steep path turned slippery. Narayana's wife, Baby, was unable to fetch water.

It is then that the radio mechanic had a brainwave. As rain is bountiful here, why not hold a funnel to the sky? The next day, Narayana bought a polythene sheet from the town and built a pandal. Whenever it rained, the water collected on the sheet. Through a hole pierced in the centre of the sheet, water would trickle into the vessel kept beneath it.

A polythene sheet of the size eight feet by four feet costs Rs. 30. But it doesn't last even for a season as the sun destroys it. Because of this, two sets of sheets were required for a monsoon season. This year, Narayana decided to get a GI sheet instead of a polythene sheet. (If oil is applied on it as a coating, he hopes it can be used for a few more years.) But all the Rs. 404 got him was a smaller sheet — five feet by four feet. The family's "catchment area" had thus decreased.

A coastal district, Dakshina Kannada receives the highest amount — 3,500 mm — of rainfall in the State. "In a normal season," points out Baby proudly, "we get three kodas of water in an hour." The first three kodas are reserved for drinking and cooking.

The couple has two daughters, Priyanka (13) and Swathy (11). The family's daily requirement of water for other uses is about 15 kodas - 225 litres. Anything in excess of three kodas is stored for purposes such as washing clothes, bathing or cleaning the toilet. Their house has a tiled roof. A portion of the roof water is collected in a barrel. This comes in handy for non-potable uses. "On some days, after our daily quota is filled, we let out the rain water," says Baby. A few buckets, vessels and a barrel provide them a storage capacity of around 300 litres. In an average year, they have got their full or partial requirement of water this way for 80 to 120 days.

The poor couple's dream of an independent water source is still unrealised. They have spent Rs. 3000 and many man hours to sink a well. By the time it reached 13 ft, all their resources were exhausted. Elders say that to get water, the well has to reach at least 30 feet. Narayana has submitted representations to the panchayat to provide them some arrangement for water. And the response has been: "If and when houses that occupy around five cents of area are built, you will get the water."

Responding to the suggestion given by the Maitri Trust, an NGO based near Mangalore that is creating an awareness on rain harvesting, Narayana now diverts all the excess roof water and run-off from his house-site into the half-finished well. "Let somebody get the benefit, if not me," he says with a smile.

Another farm labourer, Narayana in Kepulakodi, about 20 km away, also follows the same system to help tide over his water problem. It's his wife Janaki's idea. They use an old sari in lieu of a polythene sheet. (Silpaulin, an ultra-violet stabilised tarpaulin sheet is available in the market in various grades of thickness. Though initially expensive when compared to a polythene sheet, it might last longer.)

This low-cost rain harvesting arrangement is ideal for poor families and those who have no other alternative but to use hard and contaminated water. An added advantage is that this system doesn't require water-filtering. It can be dismantled and stored during summer. As such, there is no wastage of space.

These poor families might not be aware of the by now popular phrase and concept called "rainwater harvesting". Nor did anybody teach them the technique. It's sheer commonsense that they have used.

Wells in our area average nearly 1000 feet deep. This is also "historical" water which will never be replaced. At today's prices, a well would cost in the neighborhood of $25,000 -- far in excess of our budget. Ever since we visited New Zealand almost 20 years ago, we have thought about catching and storing the rain from our roof. There we found New Zealanders, rich or poor, collected the rain from their roofs and stored it in barrels or tanks. Wells were the exception rather than the rule, municipal water system almost non-existent. Why not do the same thing in our part of the Sonoran Desert where rainfall averages about 12 inches per year?
 

Initially we used a 2500 gallon polyethylene storage tank to store the rain water from the greenhouse and trailer roofs. Now the roof of the new straw bale house also has collection gutters and pipes and a 15' above-ground swimming pool to add to our storage capacity. This is usually kept covered to keep the water from getting dirty and to avoid evaporation -- which is significant in the dry Arizona climate.

We have a standard pressure tank and a 1/2 horse power jet pump to bring water from the tank(s) and maintain constant water pressure in the house.

Now all roof surfaces of the new straw bale house are guttered and piped in to the existing pipes running to the storage tank from the roof of the greenhouse. Pipes running vertically to the ground are "roof washers" -- see the section further on about these..

Note the rain water gushing into our tank from the catchment pipes during a storm. The green material is a synthetic pad for an evaporative cooler (three layers) which we are using to filter out any of the more course particles of dirt or other debris which may have gotten past the roof washers. There is an additional filter for the finer particles located between the storage tank and the jet pump.

We have over 3000 square feet of roof surface to collect rain water between the greenhouse and new straw bale house. TO FIGURE HOW MUCH WATER IS COLLECTED: approximately 600 gallons of rain water is collected for every 1000 square foot of collection area for one inch of rain. Thus one inch of rain produces about 1800 gallons of water and comes close to filling the storage tank. The new above-ground storage pool will hold about 4500 gallons.

[ Home ] [ Links to catching rain water ]

Send mail to ghazi@wavepowerplant.com with questions or comments about this web site.
Copyright © 2006 Wave Power Plant Inc.
Last modified: 04/08/06