Water is our business and our passion. In total we take 1 billion litres of used water away from homes and businesses every day, including drainage from roads, highways and public spaces.

 

​Climate change, population growth and an increase in hard landscaping – such as paved driveways - are contributing to more intense rainfall, more runoff and more sewage, increasing the pressure on the sewer system.

 

How our network works​
Our combined sewer systems transport rainwater runoff and wastewater, including sewage, in a combined pipe to a sewage treatment works. This network is designed to accommodate some storm-water runoff, but when larger amounts enter the system, storm overflows act as safety valves to prevent homes and properties being flooded and this excess water is allowed to be discharged into nearby rivers and streams.​ 
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Storm Overflows are vital in protecting people from flooding and are widely used across the UK. And to ensure they are working correctly we monitor them through Event Duration Monitors (EDM). The data is used to track their performance and allow us to respond to any issues quickly. If we find they are operating more frequently than we would like or having a detrimental impact on the environment, we undertake a series of investigations to understand how we can put things right. Read more about how we are assessing performance here. ​
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Our commitment ​
Storm Overflows are only responsible for 1-4% of reasons why the rivers in England aren't rated healthy to swim in. But we fully recognise that while they have an important job to do, they aren't the answer to dealing with overloaded sewers. And we understand our customers concern around storm overflows and the impact they can have on our rivers and wider environment. ​
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Find out more about our commitments to provider healthier rivers and inland bathing water sites here ​and explore our storm overflow map and spill data here.