Chennai: "Around 95% of the rain that falls in our house is saved, harvested, and used. We do not depend on private water tankers," said Haris Sultan, a waterbody expert and resident of Korattur. "This is because we recharge rainwater from where we extract for daily use, throughout the year," he added.
Rainwater from his 600sqft terrace and 200sqft verandah finds its way via PVC pipes into his 30ft-deep, 3.5ft-wide open well. Before entering the well, it passes through a 3ft-high filter of gravel and sand separated by a filter net. He extracts water for his household from this open well. Earlier this week, his well was 80% full. "This will last us till the next monsoon," he said.
In most cases, however, rainwater harvesting structures are just a formality to get building plan approval from Greater Chennai Corporation or the Chennai Metropolitan Development Authority. Many houses only have pipelines from terraces inside recharge pits, and nobody desilts or checks if the pits recharge water or not.
A handful of residents, however, have implemented it so well that they do not rely on private water tankers, especially in areas without water pipelines. "Our groundwater is bad. So, we have a large underground sump to save and store rainwater," said Ramesh K from Perungudi.
Haris draws his water from the open well for consumption and temporarily stores it in a 1,000l tank and a 700l tank on his terrace. Both the tanks are connected now. "Since my open well is 30ft-deep, I have an iron filter because there could be more iron content in the water, especially after April when the water level reduced in the well," said Haris. Post April or May, they separate the tanks and fill them alternatively for the iron to oxidise and solidify as iron oxide.
But Haris' neighbour has a 20 ft-deep open well with barely any iron content. He also has a borewell and recharges around it too, so that the aquifer never goes dry. The cost can range from 10,000 to 30,000 to set up a rainwater harvesting structure around the open well or borewell, which also depends on the size.
"A TDS (totally dissolved solids) metre helps in checking water quality," said Haris. The TDS standard for drinking water is 500 ppm.