Chennai: a pioneer in rainwater harvesting, failure in saving water
Across Chennai, there is a lack of awareness on the importance of a sustainable rainwater harvesting model that can save the city from such a crisis.
“Chennai has never faced such a situation. This is like being married for the first time. Everything is new,” said Sekhar Raghavan, Director of Rain Centre on a call. His phone rings incessantly much like the unsettled panic over the water crisis in the city.
Tamil Nadu was the first state to make rainwater harvesting (RWH) mandatory for all buildings in 2003. A report with data from the Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) shows that Chennai has 8.15 lakh RWH structures. If this data is accurate, the 8.09 lakh buildings would not be facing the acute water shortage.
To make things worse, nearly 90 per cent of 88 wells -- monitored by Rain Centre, a not-for-profit service organization -- in and around Chennai have gone dry. “Last year, only 10 per cent were dry. In just one year, here we are,” said Raghavan. How did it go wrong for Chennai, a pioneer in RWH in India?
Turns out, a written proof that shows a building is equipped with a RWH system is not enough. But the efficiency factor of the implemented system is neglected. Among the RWH systems, two are widely implemented, namely, percolation bore pit and recharge well. While the former is popular, the latter is efficient.
The percolation bore pit has a single PVC pipe lodged under the ground. Due to the pipe’s small diameter size, it cannot collect large quantities of water. On the other hand, a recharge well is 15 feet in depth and three to five feet in diameter, making it a compelling option for storing water as a RWH system. Moreover, the PVC pipe in the pit clogs easily as it carries all the dirt washed with the rains. Cleaning it is a herculean task and people often ignore unclogging it for that reason. A recharge well is large enough for a man to step in and perform desilting.
“During audits, we found that many buildings across Chennai did not construct recharge wells,” said Raghavan. They opted for the percolation bore pit. But why do people choose an inferior water-storage system for a superior one? The answer is quite simple.
People prefer the percolation bore pit for multiple reasons. It is cheaper to construct a pit than a recharge well. To construct a recharge well is often three times more expensive than constructing a pit. Additionally, plumbers are more accessible and construct these pits quickly. “People lack awareness and some that are aware often settle for low-cost systems without thinking about the consequences,” said Raghavan.
A man inspects a percolation bore pit installed in Mandaveli, Chennai
Newly constructed buildings across the city get a nod from ignorant CMDA officials who are approving inefficient RWH structures across the city. “The CMWSSB that is in charge of monitoring these RWH structures cares for numbers more than it does for sustainability,” said Raghavan. A recharge well lasts up to 15 years whereas a percolation bore pit lasts less than three years. “The government must educate people and look into implementing the correct system,” said Raghavan.
There is a growing need to monitor not just the amount of groundwater but also its fluctuation rates. It is not too late to begin implementing the correct mechanism as RWH is the best option that can save the city from such a crisis.