RAIN WATER HARVESTING NEEDS A NEW THRUST, SAYS NGO

As the monsoon hits the city, metro water authority and NGOs alike press for maintenance and optimisation of harvesting facilities.

26-10-10

Chennai: Severe water woes maybe a thing of the past for many of the city’s inhabitants but the policy that brought about the transformation- compulsory rain water harvesting- begs for rejuvenation, says Sekhar Raghavan, who heads Rain centre, a Santhome based NGO working to spread awareness about rain water harvesting and provide technical know-how on harvesting methods to Chennai citizens.

 Rain water harvesting was implemented widely in Chennai when it was made a compulsory requirement for gaining water and sewerage connections in Tamilnadu in October 2002. The government had then ordered that rain water harvesting be implemented in all buildings- residential and commercial, by August 2003. But after the initial excitement died down, few attempts have been made to create awareness about the importance of proper construction and maintenance of rain water harvesting facilities, alleges Sekhar Raghavan.

Chennai has an average annual rain fall of 1.2 metres, making it possible for the city to meet a large part of its water needs merely by collecting and storing rainwater underground. Rain water collected on rooftops and catchment drains around plots is usually diverted into recharge pits and wells to replenish ground water which is later extracted using bore wells. It is also stored in tanks after passing the water through a simple filter for immediate use.  Those wishing to construct harvesting facilities can contact Rain centre to gain guidance and to find trained plumbers (044- 24616134)

This year, the metro water authority has also opened a help line (044-28454080) to guide those in doubt about how to maintain existing facilities. Before the rains set in, the rain water harvesting wells and pits must be cleaned to remove silt and accumulated debris like leaves or paper that prevent water percolation, said M. Soundara Rajan, head of the Hydrology department at the Chennai Metropolitan Water supply and Sewerage Board. According to him, nearly 98% of the buildings in Chennai are equipped with rain water harvesting facilities.

But Mr. Raghavan disagrees, pointing to a survey conducted by Rain Centre in 2003 among the residents of Gandhi nagar in Adyar. It found that only a little more than 50% of the residents had put harvesting systems in place. Even this level of implementation had tremendously beneficial impact on water quality and availability in the city. After the law was implemented the water table in Chennai rose by 6 metres and wells which had run dry due to years of over exploitation of ground water achieved healthy levels again. But now, with rampant corruption leading to shoddy implementation of building regulations and a lack of awareness on proper harvesting methods, the practice has taken a hit, says Mr. Raghavan. Re-charging of ground water, which is Chennai’s primary source, through rain water harvesting needs renewed attention if the gains made earlier are not to be lost he says.

The reason for a lack of focus on rain water harvesting is due to fact that Chennai now has access to many new water sources. If the city once depended primarily on four sources: Red hills lake, Cholavaram lake, Poondy lake and Chembarambakkam lake, it now receives water from Veeranam lake which supplies 180 Million Litres per day (Mld) to the city. The recently commissioned desalination plant at Minjur in north Chennai which cost 600 crores to build and is spread over 60 acres, also supplies 100 Mld of water. The plant, a private venture, supplies water to the Chennai Metropolitan Water Supply and Sewerage Board at a cost of Rs 48.74 per 1,000 litres, a rate which will be revised after 25 years.  Chembarambakkam also has a desalination plant. One more is currently being built at Nemmeli.

This obsession with expensive, inefficient methods of water supply with little attention paid to maximising the potential of freely available rainwater will end up costing Chennai much, says the Rain Centre.