In Just 3 Hours Of Rain, Chennai Apartment Collects 1 Lakh Litres Of Water

The residents of a Chennai apartment complex have evinced the effectiveness of systematic rainwater harvesting by collecting around 1,00,000 litres of water in just three hours of rain, reported by The Times of India.
Fifty-six apartments in four blocks of Sabari Terrace Complex in Sholinganallur participated in the rainwater harvesting drive by channelising the rain pipes from their terraces into an underground sump or reservoir with an enormous storage capacity of 1 lakh litres. Beyond the expectations of the residents, the sump filled up to the brim in just a span of three days – from October 29 to October 31 – when the city registered a total rainfall of around three hours.

About the project

The residents of Sabari Terrace have been active crusaders of rainwater harvesting since 2017 when they have started constructing different RWH structures in phases. The plan for the massive sump has been on the cards for quite some time.
Explaining the structure to The Times of India, Harsha Koda, secretary of Sabari Terrace Residents’ Association, shared that the entire mechanism operates in two phases. In the first phase, the rain pipes from fifty-six terraces carry the rainwater into two tanks where sedimentation takes place, clearing the run-off water from dirt particles. These tanks deposit the water into the 1 lakh-litre underground sump which comprises the second phase. The water is then routed towards a treatment plant, where it is recycled and rendered safe for use, followed by redistribution among the local water sources.
Incidentally, the design for the sump was conceptualised by Prabha, wife of Harsh Koda, which was later finalised by experts from Rain Centre.
“Only last month all the four blocks were connected to the sump. In the three days cumulatively it would’ve rained for three hours. But that was enough to fill our sump,” Koda informed The Times of India.

Repleting the declining groundwater levels

The city of Chennai has been predominantly dependent on groundwater, whose levels are facing depletion due to unplanned usage. The Sabari Terrace sump also ensures the rise in the groundwater levels in the area. Four rain pipes originate from four corners each terrace, out of which three are connected to the sumo network while the fourth one drains the water into soak pits meant for recharging the groundwater table. In fact, sometimes excess water from the sump is also diverted towards the soak pits using valves.
Accounting the expenditure for the project, Koda reveals that out of the total Rs 2.5 Lakh spent over a year, water worth Rs 50,000 have already been recovered. The residents admit that the project has sufficiently minimised their dependence on Chennai Metrowater – the urban groundwater supply network of Chennai.
Dr Sekhar Raghvan from the Rain Centre has reminded that lack of proper maintenance can lead to clogging and failure of the system, which has yielded so much water as it is brand new. “A harvesting system has to be cleaned before every monsoon, if not twice a year. Or it would be useless as dirt and silt clog it,” he revealed.
Source: The Logical Indian
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