Here in the South we’re feeling the impact of dramatic changes in climate. In many areas, we’ve experienced the driest summer for 50-years, followed by unprecedented rainfall and stormy weather this autumn. Some areas, including Shanklin on the Isle of Wight and Odiham in Hampshire, had their wettest November day on record on 2nd November and many of us have experienced more rainfall in the last week than we would normally expect to see during the entire month.
The nation’s combined sewer overflows (CSOs) have been activated more frequently this month to avoid flooding because of the significant heavy rainfall and high volumes of surface water.
This is how CSOs are designed to work. When there’s rainfall, our network has to cope with rainwater run-off from roads, roofs, driveways and hard surfaces. Storm overflows are there to help protect our homes, businesses and schools from flooding. They are effectively a pressure release valve, activated when the system’s capacity is exceeded to allow excess flows - typically made up of up to 95% rainwater - to enter rivers and the sea. This is permitted by the Environment Agency specifically to prevent flooding, and outfalls are located up to 5km out to sea to minimise any impact to bathing waters.
Although this is meant to happen, we know that any untreated sewage going into our seas and rivers is not acceptable. Moving away from this nationwide system of storm overflows will take time but we are committed to making change happen. We’re investing £2 billion between 2020-25 to improve our performance over the next 3-years.
What we’re doing
The most efficient and environmentally beneficial way to reduce the use of storm overflows is to redirect or slow the flow of surface water which enters the sewer. We are working with partners including local authorities such as county councils, highway authorities, communities and developers to find smarter, more innovative ways of running our network and making it fit for the future. We are also working with our customers to shine a light on the actions that everyone can take to help such as installing water butts to recycle rainwater or reducing the amount of paved areas in gardens and driveways.
Our Clean Rivers and Seas Task Force is piloting many of these innovative and collaborative ideas through our pathfinder projects. For example, we are working closely with the Isle of Wight community and council, the Environment Agency and sustainable drainage system specialists to reduce storm overflow use while simultaneously reducing the risk of surface water flooding.
We also know how important it is to provide transparent and clear data around pollution incidents and we are leading the industry with how we share storm release data using Beachbuoy, our 24/7 365 near real time reporting service. This information is live on our website and shared directly with key stakeholders and bathing water users.
We are working hard, investing heavily and taking real action to reduce the use of storm overflows to create healthier rivers and seas, and we know it will take time. Our clear improvement plan, supported by the passion and dedication from our Southern Water team, will make these vital changes happen and create a water system fit for the future. The positive effects will not all be felt immediately, but we will continue to monitor and be fully transparent, reporting regularly on progress.