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Collective Wisdom

The Dewas experiment shows a way out of the crisis

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Collective Wisdom
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It may be the ultimate panacea for the recurring water problem in urban India. People have been talking of harvesting roof water for long but only now has the process been simplified, made loss-proof and hygienic. And it has been done by a non-geologist IAS officer, M. Mohan Rao, in Dewas district of Madhya Pradesh.

"I never realised water’s critical importance till I was posted here," says Rao, who is from Andhra Pradesh’s West Godavari district. It is not as if Dewas doesn’t get enough rain-it averages 100 cm every season-but the impervious black soil of the cotton-growing region and over-exploitation through tubewells has lowered the ground table to the extent that most of Dewas’ two lakh population has to struggle for water for at least three months a year. What alarmed Rao most was that the water level has gone down by over eight metres in the past five years alone. As a result, water which was available at a depth of 250 feet has dropped to below 500 feet.

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The technique developed by Rao and his team is simple and inexpensive. A PVC pipe attached to the drain in the roof is passed to a four-foot filter. At the other end, a packet of potassium permanganate is placed in a T-joint carrying the water straight to the well. It is calculated that on average, one lakh litres of water goes waste from a 1,000-sq ft roof receiving 1 cm of rainfall. If this is sent to the deep aquifers, the groundwater recharge is about 76 times greater than the natural method.

Some 21 roof water harvesters had been installed last year but their filter tank took up too much space. The latest tubular type is far simpler to install and use. And it costs under Rs 1,000. Its design is being patented as Dewas Roof Water Filter by the Bhoojal Samvardhan Mission under whose banner Rao has been operating.

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Developing the filter has not been Rao’s only achievement. He has also taken it upon himself to spread the message through street-corner meetings. A blanket ban has been imposed on drilling operations in the district. Waheed Rafiq was among the first to adapt the harvesting method last year. "There has already been a minor improvement as every year our wells used to run dry by mid-April. But this year, it appears we will have no problem through the summer," says Rafiq.

Rao feels expecting everything to change in a couple of seasons would be too much. "The groundwater has been exploited for the past so many years and aquifers will take time to recharge. By roof water harvesting, we’re trying to give back to nature what we owe it." He has already convinced nearly 2,000 homes to do so and will not stop till every tubewell owner adapts the Dewas roof water harvesting technique.

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