Treated waste water may cater to most of Chennai’s needs

While water managers are struggling to meet the needs of the metropolis, lakhs of litres of sewage water is still being let into the sea without being treated. If the sewage is treated, Chennai may  not require desalination plants or water being transported by trains.

As per the Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) claims, the board is supplying around 525 MLD (million litres per day) of drinking water on every alternate day. 

On the other hand, there are four sewage treatments plants (STP) operated by the board with a combined recycling capacity of 727 MLD every day. If the board treated all the sewage water which is generated in the city, Chennai’s rivers would not have been polluted and overflowing with waste.

Even most of the city residents remain oblivious towards the importance of sewage treatment plants. Notwithstanding the building rules mandate sewage treatment plants at multi-storeyed apartments, the majority of apartments in the core city lack suchplants. Residents’ welfare associations in Adyar and T Nagar said that none of the apartments in their locality has sewage treatment plants.

Left without water and sewage connections, apartments along Old Mahabalipuram Road (OMR) are the only ones who follows the rules and have operational sewage treatment plants.

KP Ramalingam, the president of Natural Water Resources Protection Movement said that the residents are hesitant to use recycled water. “So, the government should treat all sewage water and let it into lakes which are being used for agricultural purposes. This would also recharge the groundwater levels,” he added.

Apart from Chennai, Ramalingam also insisted sewage treatment plants in all the urban local bodies, so that not a single drop of sewage water enters rivers. “We need long term vision and more awareness. This would provide continuous supply for irrigation,” said Ramalingam.

Cooum and Adyar rivers discharge an average of 200 to 300 cusecs and 300 to 400 cusecs of sewage water into the sea every day. If this sewage water is recycled, Chennai could have clean rivers and interminable water supply, even without desalination plants.

“Metrowater ought to treat all the sewage generated in the city. As per world standards, sewage should enter treatment plants and treated before letting into drains. But, Metrowater continuously hoodwinks us,” M Karthi, a resident alleged.

Meanwhile, S Janakarajan, former professor of Madras Institute of Development Studies (MIDS) said that sewage water that is treated up to second tertiary level could be stored in major lakes such as Chembarambakkam, Poondi, Puzhal and others.

“It would cost Rs 36 per kilolitre (1,000 litres) to treat sewage water to near potable condition. Setting up of STPs in individual houses is expensive and Metrowater should expand its recycling capacity,” he added.

When asked Janakarajan about the possibility of letting the treated water directly into rainwater harvesting pits along OMR where the residents dump treated water into water bodies, he said that it could be done. But, the groundwater level in Sholinganallur area is high and already saturated. Even though groundwater is saline, we could not send all the treated water into the ground.

Despite, the several apartments in the locality have STPs, private sewage lorries collect around 700 loads of sewage water every day to be dumped elsewhere.

An apartment in Sholinganallur has set an example for Chennaiites and the government over its use of water as it treats all its sewage before letting it off the drains.

Sabari Terrace apartment in Sholinganallur has a sewage treatment plant that has a recycling capacity of 57,000 litres per day (57 Kilolitres). “There are 56 flats in the apartment and the treated water is being used for toilet flush and gardening,” Harsha Koda, secretary of Sabari Terrace Apartment Owners’ Association, said.

Denied sewage connection by the Metrowater, the residents of the apartment built the plant at a cost Rs 5 lakh.

Harsha Koda added that the recycled water, after used for flushing toilets, is being sent out using private sewage tanker lorries. “We send around 40,000 litres of recycled water by hiring tanker lorries every day. We pay Rs. 800 per load and we send four loads out,” he added.

Like many apartments in along Old Mahabalipuram Road, Sabari Terrace also buys freshwater from private tanker lorries and depends upon borewells.

When asked T Prabhushankar, executive director of Chennai Metropolitan Water Supply and Sewerage Board, whether the water manager would create awareness on setting up sewage treatment plants in apartments and effectively using recycled water, he said that the board is focussing on the drought situation as of now.

There is a common perception that recycled sewage water only can be used for flushing toilets and gardening. But, at the time when the water scarcity hit construction industry, reputed builders have been endorsing recycled water for construction purposes.

P Manishankar, the state president of the Federation of Tamil Nadu Flat and Housing Promoters Association, said, “Using recycled water for construction purposes is need of the hour, however apprehension among the builders. But, the usage of recycled water will increase in the future.”

According to Manishanker, constructing one square foot requires around 100 litres of water for curing of concrete and other purposes and the builders are procuring 12,000 litres of freshwater for Rs. 5,000 to Rs. 6,000. However, he pointed out that the government should certify quality recycled water to clear apprehensions.

Meanwhile, S Sridharan, executive committee Confederation of Real Estate Developers’ Association of India – Chennai, also endorsed the usage of recycled water for construction purposes.

“However, recycled water should be tested for its quality before usage. Recycled water with substandard quality cannot be used,” he added.

The builders also pointed out that the construction activity has come down due to the water scarcity.

“Major construction activities have been stopped and only minor works are going on,” Manishankar said.

A multi-storeyed gated community in Pallikaranai that has a sewage treatment plant within its premises has been supplying water to the Forest department.

S&S Sarvam apartment has a sewage treatment plant that was installed when the apartment was constructed. The apartment with around 200 families uses recycled water for flushing toilets and washing common areas apart from watering the garden.

“The capacity of the plant is around 130 kilolitres per day. Of the total recycled water, we use 40 per cent. For several months, we were dumping all the recycled water into drains using private sewage lorries. We came to know that the Forest department creates a walkers’ garden in Pallikaranai and we approached them to take our water for watering purpose. 

Now, they take 36,000 litres every day,” B Vijayalakshmi, former secretary of Sarvam Apartment Owners’ Welfare Association, said.

She added that the sewage treatment plant and distribution of water to the forest department has offset the maintenance cost that increased due to water scarcity. Earlier, residents of the apartment were hiring more private sewage tankers to dispose of their excess recycled water.

“Now, private tanker lorries charge more due to the scarcity, resulting in higher maintenance charges. However, we are saving on the hiring of sewage tankers,” she said.