Homes and public buildings in a London borough are set to benefit from lowcarbon heating, thanks to a unique project to recover energy from treated wastewater at a Thames Water Sewage Treatment Works.
With wastewater from around 2 million people processed at the Mogden site each day, renewable heat will be supplied to the first phase of the Hounslow Heat Network.
Heat networks supply energy from a central source via insulated underground pipes carrying hot water, offering a highly efficient alternative to traditional heating systems.
While wastewater heat recovery is relatively new in the UK, more than 500 sites worldwide already use the technology, particularly in Northern Europe and Scandinavia where heat networks are well established.
Thames Water is one of the UK’s largest producers of renewable energy from waste. In 2024/25, the company generated 475.3GWh of renewable energy, meeting 25.8% of its total energy needs.
Across London and the Thames Valley, up to 10TWh of low carbon heat could be recovered from wastewater – enough to heat more than 800,000 homes – highlighting the technology’s huge, untapped potential.
Dejan Vernon, Energy Technical Manager at Thames Water, said: “Our purpose is to deliver life’s essential service, and the heat recovery scheme at Mogden sewage treatment works will deliver real benefits for the Hounslow community.
“By capturing heat from wastewater, we can help provide low-carbon heating for public buildings, homes and essential services across the borough, demonstrating how the water sector can support the transition to net zero while delivering for customers and the environment.”
The phase one network in Hounslow has the potential to supply heat to up to 3,000 homes, as well as hospitals and NHS buildings, libraries, schools, commercial premises and other public buildings across the borough.
Heat will be distributed through approximately 8.8km of underground pipes, providing clean, reliable heating without the need for individual boilers or electric heaters.
Initial construction is expected to begin in 2028. Once operational, the scheme is projected to deliver 50GWh of low carbon heat each year, reducing annual emissions by around 6,690 tonnes of CO₂e – equivalent to removing more than 3,800 petrol cars from the road.
As well as cutting carbon, the Network will support local supply chains and create new green jobs, showing how water sector innovation can help deliver a more sustainable future for local communities.
Hounslow Borough Council secured £10.55 million in government funding from the Green Heat Network Fund (GHNF) to support the project.
A local councillor said: “We look forward to the opportunity to partner with Thames Water to utilise the heat recovery scheme in our borough to accelerate our climate ambitions.
“Cleaner energy benefits everybody in Hounslow, cutting carbon emissions while protecting residents from future price shocks.”
