CHENNAI: Chief Minister C Joseph Vijay’s announcement of 400-million-litre per day (MLD) desalination plant at Minjur, at an estimated cost of a Rs 4,800 crore, could help Chennai substantially reduce its dependence on the monsoon for drinking water, with another 400 MLD plant under construction at Perur near Nemmeli.
The two projects, together capable of producing 800 MLD, will take the city’s total desalination capacity to 1,160 MLD, almost matching the 1,160 MLD supplied by Chennai Metro Water Supply and Sewerage Board (CMWSSB) to domestic consumers.
On September 2, CMWSSB supplied 1,245.97 MLD, including 1,160 MLD to domestic consumers. Of the total supply, 1,035 MLD came from surface-water sources, 154 MLD from desalination plants, 27 MLD from groundwater and 19 MLD from quarries.
The Minjur plant will cater to North Chennai, Avadi, Ponneri, Minjur and surrounding areas. The Perur plant is expected to be commissioned in October 2027.
With the two projects becoming operational, desalination could emerge as a major pillar of Chennai’s drinking-water supply, providing a dependable source when monsoon rains fail and reservoirs run low.
The CMWSSB has 3 desalination plants at Minjur (100 MLD), Nemmeli (110 MLD) and Nemmeli (150 MLD), with a combined capacity of 360 MLD. The Minjur plant is being renovated and is likely to resume partial production of 20 MLD in October, with full-capacity production expected by the end of this year, a CMWSSB official said.
Chennai depends primarily on surface water stored in the Poondi, Puzhal, Cholavaram, Chembarambakkam and Kannankottai-Thervoy Kandigai reservoirs. Supplies are also supplemented by the Veeranam source in Cuddalore district and the Kandaleru reservoir under the Krishna Water Supply Project.
The city has no perennial water source and its water availability is largely dependent on the monsoon. Delayed or deficient rains can quickly put pressure on reservoirs and force CMWSSB to augment supplies from alternative sources.
The State government has consequently made desalination an important component of its long-term water resource augmentation strategy, aimed at improving drought resilience and ensuring a more reliable source of drinking water.
CMWSSB also extracts around 13 MLD of groundwater from aquifers at Thamaraipakkam, Magaral and Minjur. Borewells in the added areas contribute another 14 MLD, while quarry water provides about 19 MLD.
A senior CMWSSB official said, “Augmentation of water sources through the proposed desalination plant will ensure adequate and reliable water supply to the city and adjoining local bodies.”
Total supply: 1,245 MLD
Surface water: 1,035 MLD
Desalination plants: 154 MLD
Groundwater: 27 MLD
Quarry water: 19 MLD