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An Inside Look #2: Thames Water's 25 Year Drainage and Wastewater Management Plan

Updated: Jun 20, 2023

Thames Water has recently published its drainage and wastewater management plan for the next 25 years, which will see the adoption of a nature-based approach to tackling sewage discharge and flooding.

Thames Water’s Drainage and Wastewater Management Plan 2025-2050 (DWMP) outlines the water company’s proposals for reducing the risk of sewer flooding to homes and thereby, reducing the likelihood of storm discharges.

The DWMP prioritises nature-based infrastructure and aims to deliver sustainable drainage systems (SuDS) to over 70km2 of land in London.

In the city, Thames Water has elected for a “SuDS first” approach to give preference for nature-based infrastructure to be installed across the capital, ranging from water butts to collect rain from roofs and installation of swales and ponds in parks as well as wetland creation and river restoration.

For Thames Valley, the water company is seeking to remove unwanted flow specifically to target the elimination of additional water that flows into the sewers. This can come from places such as misconnected plumbing, groundwater infiltration and surface water drainage.

The population in the Thames Valley region is predicted to grow by 2.5M by 2050, while extreme weather events resulting from climate change, the loss of green areas and reduced amounts of ground which can absorb water is expected to put extra pressure on the company’s wastewater and drainage services.

Thames Water estimates £31.9bn is required over the next 25 years to overcome these challenges, within which £10.9bn will focus on storm overflows as part of the company’s ongoing plans to protect and enhance the health of rivers and streams.

Thames Water CEO Sarah Bentley said: “To protect against the challenges ahead of us, from climate change and population growth, we need to work together to provide a resilient and sustainable wastewater service for the next 25 years and beyond.

She said: “We’re committed to delivering positive outcomes for our customers, the communities we serve and the natural environment across our region. From creating more spongy and green spaces to helping prevent flooding in peoples’ homes, we want to take action to stop rainwater getting into the sewers in the first place.

“However, there are no quick fixes and this plan is the start of our journey to ensure we have systems which are fit for the future. Working collaboratively with our partners will make a big difference to wastewater activities for future generations and our precious environment.”

The company will update its shared plan every five years, working with customers and stakeholders as part of the process. The next DWMP will be published for public consultation in 2027.


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