Storm Overflows

What are storm overflows?

Storm overflows operate as relief valves built into the combined sewer system. They discharge excess sewage and rainwater to rivers, lakes, groundwater or the sea, when the sewer system is under strain. This protects properties from flooding and prevents sewage backing up into homes, businesses and streets in response to rainfall or snowmelt. The Environment Agency sets strict protective permits to limit the impact of storm overflows on the environment.

(External link)Event duration monitoring (EDM)

This records the frequency and duration of storm overflow spills. They are the primary source of data(External link) on the performance of storm overflows.

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Storm overflows discharge reduction plan

Defra's storm overflows discharge reduction plan(External link) sets stringent targets to protect people and the environment.

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Tackling storm overflow discharges

In a sewer pipe on the River Tame in the West Midlands is a small blue box, a key piece in the puzzle to tackle sewage(External link) spills.

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