Make best use of rainwater now, says J Saravanan hydro-geologist

Chennai: As Chennai yearns for more water following insufficient rainfall, experts say making the best use of all the rainwater makes all the difference. There is a need to dispel the misconceptions among residents, most of whom feel that the construction of Rain Water Harvesting (RWH)  structures cost a bomb, they say.

The first time the  initiative was introduced in the state was in 2001, when the then Chief Minister J Jayalalithaa pushed for amendments to Section 215 (a) of the Tamil Nadu District Municipalities Act, 1920 and Building Rules 1973, and made it mandatory for all new buildings to install RWH facilities. However, 18 years later, the model used is outdated and not beneficial, experts say.

People in Chennai are entirely dependent on groundwater sources to meet their water demands. “Whenever the system fails, the  groundwater aquifers of Chennai only come to our rescue. For this, RWH is of utmost necessity to sustain our groundwater,” says J Saravanan, a hydro-geologist. 

The fact that the city is in the coastal area further reminds us of how precious fresh water is and how much we need to conserve it, he says. 

The benefits outweigh the costs of setting up an RWH structure. “A simple system includes a roof water diversion which led into already existing sumps in the residence and a recharge well of 3 to 4 feet diameter and 10 to 15 feet depth,” says Saravanan. 

These two elements can cost anywhere upwards of Rs 15,000, for both these elements. “The old models cost lesser because bricks or  pebbles were used as filters. now, we sell a specific filter, which runs on centrifugal force and does not require any electricity. This would cost Rs 8,500 for a 50-1500 sq feet residence,” M Jesudasan, Managing Director of J L S Traders, a company that sells the filters.In the absence of a borewell, water can be sent into the soil by digging apit to a minimum of 10 feet to 20 feet, depending on the soil type. The nature of the soil too, needs to be tested as the terrain in the city varies. 

Government buildings need to fall in line, says Saravanan. “When Rain Centre, an RWH information and assistance centre, conducted an assessment in the city, 90 per cent of the residences seemed to comply. They have done it properly and with good design. The major defaulters are government buildings,” Saravanan says. “These buildings need to practice, not simply preach,” he said.