Southern Water confirms real progress on sewage storm overflows in Sussex – for cleaner rivers and coastlines
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“Communities across Sussex have been clear: they want cleaner rivers and coastlines, and they want to see real, sustained progress.”
These are the words of Nick Mills, Director of Environment & Innovation, Wastewater, Southern Water, who says the company is delivering real progress on tackling the root causes of storm overflows, and has given this update below.
We know trust has to be rebuilt, and we’re determined to take on the challenge and set Southern Water on a path to help create cleaner rivers and healthier seas. That’s why we’re taking urgent, practical action to reduce storm overflows and protect the places we all care about. At Southern Water, we’re now one year into our £1.5 billion Clean Rivers and Seas Plan. This investment is focused on tackling the root causes of storm overflows, preventing rainwater and groundwater from entering the sewer network in the first place, so that we can make lasting improvements.
And whilst there is still a long way to go, early results show that this approach is working - over the past 12 months, more than 700 storm overflow releases have been prevented across our region.
In Sussex, we will invest more than £300m over the next five years, focusing on some of the most environmentally sensitive areas. Most of our programme is a hybrid mix of catchment solutions optimising existing systems, new green infrastructure and upgrading of assets. These are designed to reduce the use of storm overflows, support biodiversity and create more resilient local environments.
In West Sussex, we’ve completed 16km of sewer sealing, the largest volume delivered in any county. Our Lavant wetland, installed in 2024, has ensured all overflows from site are treated. We’ve also surveyed a further 4,456 properties across Burgess Hill, Bognor Regis and Hurstpierpoint, with community engagement now underway to support future roof separation schemes. This is about precision as much as pace – using data and local insight to apply the right solution in the right place.
Across East Sussex, we are focusing on early-stage assessment and targeted groundwater reduction in the areas most at risk. In Fairlight, we’ve completed 2km of sewer sealing, reducing groundwater infiltration into the network. We’ve also surveyed 685 properties in Hailsham, creating a strong evidence base to inform future roof separation delivery.
There is no one-size-fits-all answer. Every catchment behaves differently, which is why we have invested over the past two years in pathfinder projects to test a wide range of interventions. We now know what works best in different environments and we are scaling those solutions accordingly.
This is a complex, nationwide issue made more challenging by climate change and population growth. But early results demonstrate that sustained action is beginning to shift the dial.
There is much more to do, and we are clear about the scale of the task ahead. By accelerating delivery and working collaboratively across the region, we are building the long-term resilience needed to create healthier waterways for our customers and communities.
Discover more
Find out more here: Clean Rivers and Seas Plan | Southern Water