Chennai: Catering to the needs of 22.67 lakh people and touted as a step towards a “greener, more sustainable future”, Chennai’s fourth desalination plant will come up in Perur on East Coast Road.
On Monday, Tamil Nadu Chief Minister M.K. Stalin laid the foundation stone of the plant, which will convert seawater into drinking water. It will cater to areas falling under Tambaram Corporation, Greater Chennai Corporation, and 20 village panchayats near the city.
Posting on X, Stalin said the plant, to be completed by December 2026, would “fulfil the long-felt water supply needs of OMR (Old Mahabalipuram Road), ECR (East Coast Road) and GCC (Greater Chennai Corporation) areas in South Chennai. Together, we are shaping a greener, more sustainable future!”
To be built by the Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) with funding support from the Japan International Cooperation Agency (JICA), the project’s estimated cost is Rs 4,276.44 crore. It will treat 400 million litres of seawater per day (MLD), according to the government statement.
However, environmentalists in the state have questioned whether the project really is “greener”. They say that Chennai does not require another desalination plant, and that there will be a severe environmental impact.
“The plant will be a high energy guzzler, and will require at least 100 megawatts of power to desalinate the water. For a 400 MLD plant, approximately Rs 2.5 to 3 crore will be spent daily,” said G. Sundararajan, climate activist and environmentalist.
In a rain-sufficient city like Chennai, environmental experts suggest an alternative plan of rejuvenating and increasing the capacity of the existing water bodies in the city for better storage and use of rainwater.
Residents of OMR, who have been dependent on private water tankers, are not sure if the new plant will cater to their needs. “For over a decade, residents of OMR and ECR have been dependent on tankers, private lorries…Even the Nemmeli (desalination) plant is just 6 km from OMR, but does not supply to the region. It caters to the needs of Central Chennai…,” said Harsha Koda, co-founder, Federation of OMR Residents Associations (FOMRRA), an apex body of OMR residents’ associations.
ThePrint tried reaching Municipal Administration and Water Supply Department secretary D. Karthikeyan via calls and text messages but did not receive a response. The report will be updated if and when a reply is received.
Chennai’s desalination plants
The DMK government has backed desalination plant initiatives in the state. In Chennai, there are currently two plants operational, one to be inaugurated soon, and the foundation stone has just been laid for the fourth.
Work began on the capital city’s first desalination plant in February 2007, when Stalin was the rural development and local Administration minister in the then DMK government. The project in Minjur, with a capacity to treat 100 MLD of seawater, was completed in July 2020. The plant helps to meet the water requirement of nearly 10 lakh people in the north Chennai region.
The Nemmeli desalination plant, which caters to the needs of close to 9 lakh people, has a capacity of 100 MLD. Its foundation was laid in 2010 by the DMK government and it was inaugurated in 2013 by J. Jayalalithaa when the AIADMK was in power.
The work on the third desalination plant, also in Nemmeli, is in its final stage. Once operational, it will have a capacity of 150 MLD, with 23 treatment plants. It will provide water to more than 9 lakh people in areas including Ullagaram-Puzhuthivakkam, Velachery, Madipakkam, Kovilambakkam, Nanmangalam, Kilkattalai, Moovarasampettai, and Pallavaram.
With a water requirement of approximately 1,400 MLD, Chennai curently has a supply of 1,060 MLD — including the regular supply from groundwater and water tankers. The new desalination plant is expected to make up for the shortfall.
But environmentalists urge the government to look at alternative measures. Speaking to ThePrint, S. Janakirajan, a former professor at the Madras Institute of Development Studies (MIDS), said the state uses only 1 percent of the rainwater it gets. All water needs can be by using just 2 percent, he asserted.
“Twenty-five TMC (thousand million cubic feet) is the rainwater requirement of Chennai and the neighbouring districts of Tiruvallur, Kanchipuram, and Chengalpet. Desilting and increasing the capacity of the 4,000-odd lakes in the region would mean sufficient storage,” he said.
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Water woes
In the OMR region in south Chennai alone, there are more than 1 lakh apartments that require close to 4,000 tankers in total for their daily needs. Residents’ welfare associations in the area allege that pipeline work for both water and sewage lines is pending in many places.
“There has been no proper city planning. We just have people who are fixing specific complaints, putting one stormwater drain here, a small patchwork there,” Koda said, adding “For several years, people in OMR have been waiting for the last leg of the pipeline to be laid for water supply.”
Jankarajan said, “Average annual rainfall for Chennai and the three adjoining districts, what you would call the Chennai Metropolitan Area, is about 1,400 millimetres. Seawater desalination plants in a Middle Eastern country or in a water-scarce area makes sense. But you are in an area where rainfall is quite high.”
Echoing Sundararajan, he said that a plant of this capacity will have high power demand. The demand would be met with fossil fuel-based energy, which would lead to greenhouse emissions.
Janakarajan warned of the impact that such plants may have on the coastal ecosystem. “Four hundred MLD of potable water generation every day means it will have to suck in eight or 10 times that volume of raw seawater and release brine back into the sea, which will have a very high TDS (totally dissolved solids) level.”
“Its impact will be manifested in reduced fish catch. Small fisherfolks will be the worst affected. Also, the life system on the shore, backwater canals, creeks, lagoons, estuaries, coastal wetlands etc. will be badly affected, and such areas may become dead zones after a few years,” he added.
According to media reports, the TDS level of water piped from the Nemmeli plant to Thiruvanmiyur has been found to range from 700 to 1,000 ppm (parts per million), way above the safe limit of 500 ppm. But officials of Chennai metro water department have said that this reading was incorrect.
With high TDS in water from one of the two functional desalination plants, environmentalists say such water cannot be consumed directly, stressing the need for fresh water.
“For the amount to be spent on this plant, there are so many other alternative measures that can be taken, such as rainwater harvesting and desilting lakes and ponds to increase their capacity. There are close to 4,000 lakes that can become storage systems,” said Sundararajan.
Meanwhile, Koda said, “This government has been engaging with experts and has been collecting reports and information on our requirements. We have to wait and see how the execution part of it goes. The moment water comes in our tap lines, we will believe the government’s promise.”
(Edited by Smriti Sinha)
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