Southern Water submits Portswood upgrade plan for March 2030

southern water has submitted a screening opinion application to Southampton City Council for major proposed work at Portswood Water Treatment Works off Kent Road in St Denys. The company says the upgrade is needed to increase treatment capacity and improve process resilience.

The plans cover new and upgraded treatment and pumping infrastructure, electrical systems, access improvements, and the removal of redundant plant. Completion is not anticipated until March 2030.

Portswood Water Treatment Works

A screening application is a technical step that decides whether a full environmental assessment is needed. Southampton City Council’s planning portal holds further details and allows comments to be lodged on the proposal.

John Savage, the Portswood councillor and cabinet member for environment and net zero, said he welcomed investment at the site but raised concerns about the scale and timing of the work. “It’s an antique, that site, and it’s about time we got some decent investment,” he said.

He added: “But it’s also a very cramped site, and it’s going to take an awful long time to do.” Savage also said: “a miserable four years or so for local residents and harmful to the environment.”

John Savage and Satvir Kaur

Savage said there was no mention of final UV treatment at the site. Satvir Kaur, the MP for Southampton Test, said she had requested a meeting with Southern Water’s chief executive to find out what the company will do to mitigate any adverse impact on residents.

The planning filing leaves residents facing a long project window if the work goes ahead, with the site upgrade described in documents as a major change to existing treatment operations. The practical next step for anyone affected is to review the application through Southampton City Council’s planning portal and submit comments there.