Work is on in full swing to construct Chennai's fourth desalination plant at Perur along the East Coast Road (ECR). Civil work has begun to build the facility at Perur, which may be the largest desalination plant in South-east Asia.

Excavation work to build various units, such as intake sump and treated water storage system, has started. Moreover, work to build a compound wall and provide separate access roads to two burial grounds on the site is also in progress. The new plant will have various components such as lamellar clarifier units, dissolved air flotation, and gravity dual media filters (GDMF) to separate total suspended solids in the seawater. The project is likely to be completed by December 2026. 

The seawater reverse osmosis (RO) desalination plant will have two 200-MLD units, with capacity to treat 400 MLD in total. This will ensure that the plant produces 200 MLD of treated water at any given point of time, as per Chennai Metropolitan Water Supply and Sewerage Board. The Rs 4,276-crore plant will also incorporate the recommendations of the National Institute of Ocean Technology (NIOT) on environmental impact, including an erosion management plan. Units will be added for post-mineralisation of treated water before supply. 

The site is a few km from the existing plant at Nemmeli, where the third desalination plant, with a capacity to treat 150 million litres of seawater a day at Nemmeli, is likely to be inaugurated soon.

The work is being executed as a joint venture between VA Tech WABAG and Metito Overseas, and is funded by the Japan International Cooperation Agency (JICA). The treated water will be supplied through a 59-km pipeline to a new pumping facility at Porur, from where it will be distributed to other areas. Nearly 22.62 lakh people, including those in the Greater Chennai and the Tambaram Corporations, will benefit from this plant.