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TN Man’s Car Parking Space Doubles Up As a Rainwater Harvesting System. Here’s How!

Eco-warrior Kandasamy Subramani also pays no electricity bills, thanks to a simple solar plant and a roof garden that keeps his house cool!

TN Man’s Car Parking Space Doubles Up As a Rainwater Harvesting System. Here’s How!

Kandasamy Subramani, a doctor who heads the intensive care unit at the Christian Medical College, Vellore, pays no electricity bills! Yes, you read that right. And it is all because of the five kW solar plant that supplies electricity to his entire house. He also has a roof garden that keeps his home cool but the rainwater harvesting tank underneath his car parking slot is definitely catching people’s attention.

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Around 10-12 years ago, Subramani’s gated community started facing water issues and began to think of ways of conservation.

The car park before the sump was built

One day, when he was walking in the rain along the paved path in his society’s grounds, Subramani noticed that all the rain water was running into the drains. Though this was not something new and had been going on since the apartment came up, watching the fresh water going to waste like that made Subramani think of ways to stop it.

“We put speed breakers on the roads and constructed structures to recharge groundwater. We even took water from the roof of the clubhouse and put it into the recharging pits,” he told us. The speed breakers slowed down and diverted the flow of water through a casing pipe into the recharge pits dug 30 feet deep into the ground.

This exercise was at the community level.

However, working at a personal level, Subramani constructed a rainwater harvesting system in his house around four years ago.

In progress

With the help of his friend, a civil engineer, Subramani procured the required materials, referred to the Centre for Science and Environment (CSE) Delhi and various other internet sources to help clear the technicalities. Subramani managed to have the system built for Rs 4 lakhs. He says that now, the construction cost would be Rs 10 lakhs.

The two friends monitored the rain patterns for four years and collected the data to assess what the capacity of the tank should be.

They then built a 60,000-litre sump underneath the car park. But why the car park? Subramani is a firm believer in not wasting, and that includes space. He decided that the area under the car park, which would normally remain unused, was perfect for this structure.

First, they dug out a cavity in the car park for the tank. They then built a two-tier filtration system whose first level is charcoal and gravel. The second level consists of three layers of gravel and one layer of river sand to deal with organic matter and microbes and to check the odour respectively. A pipe connects the rooftop to the filtration unit, and another connects the filtration unit to the sump. The sump is covered by a slab of concrete that can easily hold up to 3 tonnes of weight. Subramani says he can park three cars on top of it. As no sunlight enters the sump, it eliminates the chances of algae formation, and the water remains clean.

When it rains, the water from the rooftop is directed through the filtration system into the sump. This filtered water is then pumped into the tank on the terrace for daily use.

60,000 litres sump with space for two cars on top

The collected water is sufficient for about eight to nine months of use, depending on the number of people consuming it. The water is used for cleaning, bathing, and almost everything else except in toilets, for which Subramani still uses borewell water since he feels that if the harvested water is used for flushing toilets, then it would deplete very fast.

Subramani purifies the same water with an RO filtration system before drinking and cooking purposes. The conscientious doctor says that the complicated designs for rainwater harvesting systems that builders give are not required. He designed this system with the help of a few friends and resources from the internet, proving that we can do anything we put our minds to.

The Facebook post he put up after his rainwater system started working garnered an overwhelming response which he had not expected. “I never expected it. I posted it on a Facebook page called Tamil Nadu Weatherman intending to help people who wanted to do the same, but this received a much bigger response than I had expected,” smiles Subramani.

He hopes his post will encourage more people to adopt sustainable environmental practices like rainwater harvesting.

Subramani has a message for all citizens: “We create the problems we face, and the solution is not difficult. People hesitate to spend money to save water but spend to buy water. You don’t have to have anything complicated – a simple pit will do,” he adds.

(Edited by Saiqua Sultan)

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