Thames Water is carrying out a £400m upgrade over the next seven years to improve Coppermills Water Treatment Works in Walthamstow, London.

The upgrades will improve the site’s capacity to meet the needs of customers, with the site responsible for supplying water to Londoners. Work scheduled to begin in spring 2026.

The site is an integral part of Thames Water’s supply network to London, and this significant upgrade will enhance the site’s efficiency, reliability and ability to serve London’s growing population.

 Upgrades include a new high-lift pumping station, a new slow sand filter recirculation system and improved power supply through a new electricity substation.

Mark Gelinski, senior project manager at Thames Water, said: “Our purpose is to deliver life's essential service, so our customers, communities and the environment can thrive.

“As custodians of important infrastructure, we need to ensure that our sites are resilient to the pressures of London’s growing population and climate change.

“Upgrading and investing in our assets is essential to this and this project will mean improved water security for Londoners as we continue to deliver a secure supply of high-quality drinking water for customers across the capital.”

 Thames Water is also upgrading Hampton Water Treatment Works to future-proof London’s water supply and the full programme of work is due to finish in 2032.

The work will be carried out by ACCIONA, which will build a new pumping station, design a new filtration system to ensure water quality and improve the electrical systems.