Event Duration Monitors - or EDMs - are located throughout our wastewater network at all points where spills are allowed to occur when there is too much wastewater due to excess rainfall, or blockages.

These monitors mesasure the levels of wastewater in our sewers at either two minute of 15 minute intervals and send that data to us either whenever a spill starts or stops, or once a day when ther have been no spills.


This provides us with an almost real-time picture of spills should they occur. This data is also useful for the Environment Agency to monitor the performance of all water companies when it comes to storm overflow activity. These monitors provide us with vital insights to understand how our sewers and treatment works are performing and more importantly, where improvements are needed.

The environment is at the heart of everything we do.

We take water from the environment and return it back to nature in the best possible condition.


We have set the ambitious goal of having the best rivers and beaches in the country in our operating area, and zero pollutions as a result of our assets and operations. 


We're well on our way to achieving that!

32 out of 34 bathing waters in our region are classed as Excellent or Good.


And we have some of the lowest levels of pollution events of water companies in England as measured independently by the Environment Agency.

What are storm overflows?

Storm overflows protect customers’ homes and the environment from flooding.


During heavy rainfall, storm overflows are like a relief valve on our network, and used only when it's completely necessary, releasing excess stormwater into nearby rivers or the sea. They're closely monitored and used in line with permits from the Environment Agency. 


As well as protecting customers’ homes and the environment, they protect our sewer network from intense demand, caused by heavy rainfall. A small amount of our network contents can be mixed into this overflow, but, due to the amount of rainwater, this will be significantly diluted down.


We've invested over £350 million into bathing water improvements. Thanks to this investment, our storm overflows should not affect bathing water quality in the bathing season, except during intense rainfall events.


Pollution incidents associated with SOs have fallen significantly through our industry-leading monitoring and pollution management approach. 

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