Chennai’s three working seawater desalination plants can together produce 350 million litres a day (MLD): 100 MLD at Minjur in the north and 100 MLD plus 150 MLD at Nemmeli on the East Coast Road. A fourth plant, 400 MLD at Perur on ECR, was about 60% complete in February 2026 and is due to be commissioned by March 2027, Metro Water managing director T.G. Vinay told DT Next. When it is running, desalination capacity will more than double.
On 2 September 2026, Chief Minister C. Joseph Vijay also announced a second 400 MLD plant at Minjur, estimated at Rs 4,800 crore, to serve north Chennai, Avadi, Ponneri and Minjur, DT Next reported from the Assembly. It is part of a roughly Rs 7,000 crore water and sewerage package for the state’s cities, which also includes Rs 500 crore for round-the-clock supply in Avadi and Rs 236 crore for drinking water and sewerage upgrades in Perambur, Kolathur, Villivakkam and Egmore, according to a second DT Next report. Here is where each plant’s water goes and why it matters during dry spells.
The plants at a glance
| Plant | Capacity | Status | Main areas served |
|---|---|---|---|
| Minjur | 100 MLD | Operating | North Chennai |
| Nemmeli I | 100 MLD | Operating | South Chennai |
| Nemmeli II | 150 MLD | Operating since February 2024 | South Chennai |
| Perur | 400 MLD | Under construction; target March 2027 | South-west Chennai, Tambaram and 20 panchayats |
| Minjur II | 400 MLD | Announced September 2026 | North Chennai, Avadi, Ponneri, Minjur |
Capacity is the most a plant can produce. Actual daily output varies with maintenance and demand. For comparison, the Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) was supplying about 1,230 MLD in total from its lakes and desalination in early 2026, according to the same DT Next report.
Minjur: the north Chennai plant
The city’s first desalination plant, at Minjur on the northern coast, produces 100 MLD and was built at a total cost of about Rs 500 crore, DT Next reported during a 2024 ministerial inspection. Its water feeds several areas of north Chennai. The new 400 MLD plant announced this September would be built in the same area; no construction timeline has been given yet.
Nemmeli: two plants for the south
Nemmeli, on ECR south of Kovalam, has two plants on the same site. The newer 150 MLD unit was inaugurated in February 2024, DT Next reported. Nemmeli water supplies residential areas in south Chennai. You can see how far it reaches from the notices Metro Water issues when the plant shuts for maintenance. During one such shutdown in 2024, alternate-day supply was announced for the Teynampet (9), Adyar (13), Perungudi (14) and Sholinganallur (15) zones, covering 38 areas including Mylapore, Triplicane, Besant Nagar, Mandaveli, Velachery, Neelankarai, Palavakkam and Madipakkam, plus parts of Tambaram Corporation, according to DT Next.
Perur: the big one coming in 2027
The Perur plant is being built with loan assistance from the Japan International Cooperation Agency (JICA). Its estimated cost has risen to Rs 6,078.40 crore. When the foundation stone was laid in August 2023, the estimate was Rs 4,276 crore and the plant was billed as the biggest of its kind in Southeast Asia, DT Next reported. Key features, from the February 2026 progress report:
- two seawater intake pipes about 1.1 km long and a 756 m brine outfall, all laid under the seabed;
- pretreatment with clarifiers, dissolved air flotation and dual media filters, followed by reverse osmosis;
- a 59 km pipeline to Porur, of which only 4.1 km had been laid at the time;
- about 22.67 lakh people to benefit across the Greater Chennai Corporation, Tambaram and 20 neighbouring panchayats.
The pipeline is the piece to watch, because the plant cannot deliver water to homes until it is laid. The ₹3,108 crore Ring Main System launched in October 2026 is meant to let Metro Water move water between sources, which should help distribute Perur’s output.
Why desalination matters for residents
Desalinated water does not depend on the monsoon, so it is the most reliable part of the supply when reservoirs run low, as in summer or a weak monsoon year. The trade-offs are cost and energy: reverse osmosis uses a lot of power, and the salty brine must be discharged carefully to protect fishing grounds and marine life. If your tap supply drops suddenly, check whether a desalination shutdown has been announced. Metro Water posts supply notices and takes complaints through its website, including its Dial for Water service.
Quick answers
How many desalination plants does Chennai have?
Three operating plants with a combined capacity of 350 MLD, at Minjur and Nemmeli. Perur, 400 MLD, is due by March 2027.
Which areas get Nemmeli water?
Mainly south Chennai, including the Teynampet, Adyar, Perungudi and Sholinganallur zones, and parts of Tambaram.
When will Perur desalination plant be ready?
Metro Water has targeted commissioning by March 2027.
Is a new Minjur plant planned?
Yes. A 400 MLD plant costing about Rs 4,800 crore was announced in September 2026.
Information checked against official sources on 18 October 2026. Fees, dates and rules can change; confirm on the linked official pages before acting.
Sources
- Perur desalination plant to add 400 MLD to Chennai’s water supply by 2027 (DT Next)
- Minister K.N. Nehru inspects 400 MLD desalination plant in Perur (DT Next)
- CM Stalin lays foundation stone for seawater desalination plant (DT Next)
- Maintenance at Nemmeli desalination plant to affect supply to four zones (DT Next)
- AIADMK, DMK councillors clash over credit for Nemmeli plant (DT Next)
- CM Vijay announces urban infra projects including 400 MLD desalination plant (DT Next)
- Rs 7,000 crore water projects for metro cities (DT Next)
- Chennai Metropolitan Water Supply and Sewerage Board
