Ajayptp / Shutterstock.com

For the people of Kerala, in southern India, rain collected from rooftops has been a lifesaver.

In her prize-winning novel The God of Small Things, Arundhati Roy describes monsoon-struck Kerala, in southwestern India, with great lyricism:

The countryside turns an immodest green. Boundaries blur as tapioca fences take root and bloom. … Boats ply in the bazaars. And small fish appear in the puddles that fill the PWD potholes on the highways.

It is a bit shocking, then, to realize that although Kerala receives 10 feet of rain during the yearly monsoons, it typically faces a severe water shortage during the preceding summer months. This is partly due to its undulating topography, which helps water run off into the Arabian Sea.

Although Kerala receives heavy rains each monsoon season, it still faces water shortages. (Byelikova Oksana / Shutterstock.com)

But another reason, according to a report prepared by India’s Planning Commission (which doesn’t mince words), is “unscientific, uncontrolled, and unscrupulous” practices such as demolition of hills, excessive pumping of groundwater, water wastage, and sand mining from river beds. As a result, a sizable fraction of the state’s 4.5 million open wells have now either dried up or contain brackish water.

To meet the needs of the state’s 35 million people, a program called Jalanidhi, created by the Kerala government and the World Bank, has helped bring piped water to many households since 2000. People interested in digging new wells, drilling bore-wells, or building mechanisms to draw water from streams and rivers have received financial and technical aid.

Another approach, rainwater conservation, has become common in the last decade, even though it is not exactly a new concept. Large reservoirs made of mud were traditionally built to catch surface runoff, and Keralites use the collected water for irrigation.

Since the mid-2000s, NGOs and the Kerala government have been trying to popularize roof-water harvesting as a viable solution, one that allows people to use their dry or discarded wells for conservation and groundwater recharge.

When Kurian Baby was district magistrate in the Thrissur district between 2008 and 2009, he began to work on a scheme called Mazhapolima, which has popularized the concept of recharging wells through roof-water harvesting. A local newspaper launched a campaign to raise awareness.

Under this initiative, employees of about 100 NGOs received training to install roof-water harvesting systems. Mazhapolima gives subsidies to poorer households and in over-exploited groundwater blocks and areas with high salinity, but most households pay a standard installation cost of $100 or $75, depending on whether a sand filter is used.

Trained staff from an accredited NGO typically install a system that allows roof water to slide into a gutter that’s connected to a PVC pipe. The water then passes through a filter to the well. The filter is made of charcoal, pebbles, sand, and other locally sourced materials. For thatched roofs, a PVC sheet is spread over the thatch.

Roof-water collection actually helps recharge dry wells and can raise the water table. (Courtesy of Mazhapolima)

“The effect of well recharging is a cascading one,” Baby explains. “These wells tend to be in regions with laterite or sandy soil, and the bottom of the wells are not closed by concrete. When the water table is low, the water is retained in the wells for a while, and then gets pushed into the ground.”

So when multiple wells are recharged in an area, the groundwater table goes back up. “The wells tend to retain water better the second year, and by the third year, impurities and salinity disappear because freshwater pushes older water down,” he adds.

So far, about 100,000 people have benefited from the initiative in Thrissur.

Anthony Kunnath is executive director of an NGO called Planet Kerala, which introduced roof-water harvesting systems to two coastal areas. “In rural areas,” Kunnath says, “gram panchayats [village-level self-government organizations] had been spending a great deal of money obtaining drinking water through tanker lorries. They now spend some of their budget building roofwater harvesting facilities.” Seven or 8 percent of a gram panchayat’s budget is spent on water and sanitation, Baby estimates.

There are about 1,000 gram panchayats in Kerala. Baby’s hope is that the Thrissur model will be adopted by the majority of them in coming years, and representatives will reach out to every household. This work has already started. One gram panchayat won a national award given by the Indian president for recharging all the wells within its jurisdiction.  

In 2004, the government of Kerala made it mandatory for almost all new buildings to incorporate rainwater harvesting systems. Compliance is well below that target—in the city of Kochi, 30 percent of houses are now harvesting rainwater, according to a newspaper report, though that could be an optimistic estimate. Even so, Kunnath says there is anecdotal evidence that groundwater levels have risen in areas where rainwater harvesting is being practiced.

With climate change, population growth, and rapid urban development having an impact on virtually every region of the world, threats to water security will only increase. Thrissur and Kerala may turn out to be models in unlikely places. In 2010, members of the U.S. National Oceanic and Atmospheric Administration and other experts considered how roof-water harvesting could help California restore its salmonid fish population.

Top image: Ajayptp / Shutterstock.com

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