Dwr Cymru Welsh Water
Combined Sewer Overflows & Event Duration Monitoring

At Welsh Water, we are proud to provide over three million people with a reliable source of drinking water whilst protecting public health and the environment by removing and treating wastewater safely and responsibly.

This is a big responsibility and as a company owned on behalf of its customers, we are determined to use the trust placed in us to do the right thing when looking after the environment—both for today’s customers and future generations.

One of the most important things we do is protect public health by taking away wastewater—which can include foul sewage and rainwater from roofs, gardens, and roads—from homes and communities to be treated and returned safely to the environment.

Combined Sewer Overflows

Sometimes, particularly during very heavy rain or storm conditions, we have to prioritise protecting our customers and their homes and businesses from any flooding from our sewers

Event Duration Monitoring

We need to understand how often our CSOs operate and, since 2013, we have invested in Event Duration Monitoring (EDM) systems.

CSOs with EDM systems

Blue Flag Beaches


To find out more about the water quality in your area, please visit our water quality page, its only a click away! Full PDF print outs are available if required.

Check My Water Quality