Why desalination plants are not the solution to Chennai’s growing water needs
As Chennai gets ready to welcome its fourth desalination plant, experts warn that the costs may be terrible in the long run and say the solution lies elsewhere
Chennai, faced with an ever-expanding population and water shortages, is about to get a fourth desalination plant, touted to be one of the largest in Asia.
As Tamil Nadu’s capital city grows more and more dependent on desalination plants, environmentalists say the answer to its water crisis lies not in these but in desilting and deepening existing water bodies.
Double whammy
Chennai currently operates three desalination plants. The fourth one is being constructed in the suburb of Perur.
Interestingly, the Chennai Metro Water Board had to rely on desalination plants to meet the city’s water needs this summer even though the city experienced intense rains from Cyclone Michaung in December 2023.
So, Chennai seems to have landed in a difficult situation — battling floods during rainy season and depending on desalination plants to meet its water needs in summer.
Experts are now asking whether Chennai is becoming too reliant on desalination plants, neglecting the implementation of action plans to revive existing water bodies for sustainability even as the city’s population grows and expands into suburban areas.
Water sources
According to the Chennai Metro Water Board, the city requires 1,000-1,070 million litres per day (mld) of water. Currently, water is drawn from six major sources: Poondi, Cholavaram, Puzhal, Thervoi Kandigai, Chembarambakkam and Veeranam lakes.
However, Veeranam lake, a major source for Chennai, dried up this year, prompting the city to turn to desalination plants. A quarter of Chennai’s water needs — 250 mld — were met through the plants.
The upcoming desalination plant, estimated to cost Rs 4,276.44 crore, can treat 400 million litres of seawater a day. It is expected to be ready by December 2026.
Water scarcity
A senior Chennai Metro Water Board official said: “For several years, the three desalination plants met emergency requirements, which typically do not exceed 150 mld. But this year, a quarter of the total supply — 250 mld out of 1,000 mld — was addressed through three desalination plants.”
According to the official, the fourth plant will play a key role in averting water scarcity.
Activist’s warning
However, environmentalists like G Sundarrajan argue against building new desalination plants, warning they could attract floods and lead to environmental damage. He emphasizes the importance of desilting and deepening existing water bodies to meet the city’s needs.
The upcoming desalination plant, estimated to cost Rs 4,276.44 crore, can treat 400 million litres of seawater a day. It is expected to be ready by December 2026 | Representative image: Wikimedia Commons
“The amount of money and energy utilized to filter water in these plants is quite high. This would actually force us to rely on thermal power plants over the years,” he said.
According to him, Chennai and neighbouring towns like Chengalpet, Kanchipuram, and Arakonam had a chain of water bodies whose desilting and deepening would dramatically improve the water situation.
Environmental damage
He added that brine water released from the desalination plants would erode the seabed.
“The wastewater from these plants is let out into rivers and the sea, which would affect the marine ecosystems beyond repair,” Sundarrajan warned.
“Considering the number of floods and droughts in recent years, the state should move towards a sustainable green model, which will be a permanent solution,” he added.
“Invitation to disaster”
Renowned water conservationist Rajendra Singh also criticized the addition of desalination plant projects in Tamil Nadu, given the surplus rains and frequent floods.
He highlighted the need for conservation and flood management strategies in various cities which would contribute to sustainability.
“Desalination plants might seem like a solution now, but they are an invitation to disaster. The city has witnessed floods once every 10 years in the past 50 years. With extreme weather events becoming more common, conservation and flood management designs are needed for the city,” Singh added.
Examples abroad
Singh said countries like France and Mexico were focusing on the conservation of water bodies and community-driven initiatives to prevent natural calamities and design sustainable water supply systems.
“France is focusing on well conservation, water-efficient farming practices, and ensuring supply through a public firm in Paris. In Mexico, several water bodies are being revived,” he pointed out.
“These sustainable projects would act as solutions. Reviving and protecting Chennai’s rivers and water bodies would be the only solution to combat calamities and ensure sustainable water supply,” he said.
Official viewpoint
Chennai Metro Water Board officials say their focus is solely on avoiding water scarcity. Maintaining and reviving water bodies fall under the purview of other departments.
“Our focus is solely to avoid water scarcity. Believe it or not, several IT firms have moved from water-starved Bengaluru to Chennai because of (our) desalination plants,” the official told The Federal.
“We are focussed on the growth of the city and want to avoid water scarcity situations like in the early 1990s and in 2019.
“During those times, we transported water from Vellore and Erode to Chennai through trains and trucks. Now Chennai is known as the desalination capital of India and promises water supply without fail.”
