Storm overflows have been part of the sewer system for generations.  Originally designed to protect homes and businesses from flooding during heavy rainfall. Our long-term aspiration is a future where we will no longer need to use overflows. 

Our five year Business Plan sets out our £1 billion investment to reduce storm spills ahead of the government's 2050 deadline. To protect our environment and support growing communities, we’re already making upgrades to all our storm overflows as outlined in our Storm Overflow Action plan, built together with The Rivers Trust, Natural England and the Environment Agency. We’re also creating nature-based solutions, such as wetlands and sustainable drainage, as well as building more storm tank capacity to reduce the pressure on sewers – all whilst improving monitoring to predict and prevent spills.

The work we’ve completed so far is already making a real difference. In 2025, our storm overflow performance reached its best level yet, with spills down over 60% and total duration of all spills reduced by over 80% compared to 2024. Drier weather helped, but even compared to 2022, when rainfall was similar, results are better showing our efforts are creating change.