United Utilities reveals significant reduction in storm overflow spills

United Utilities’ multi-million-pound investment plan to reduce spills from storm overflows is moving at pace across the North West. 

Despite more rainfall in 2024 and nine named storms, official figures released by the Environment Agency (EA) have today confirmed the company's annual event duration monitoring (EDM) submission reporting a 31% reduction in spill duration, with the number of spills from storm overflows falling by 20%.  That’s 19,720 fewer spills compared to the prior year.  

Over the next five years, United Utilities will undertake the largest ever investment in water and wastewater services in the North West, spending more than £13 billion to deliver for the environment, improve the health of rivers and seas and tackle leakage.      

As part of this investment, it will tackle more than 1,100 storm overflows and reduce activations by over 60% by 2030 delivering the step change people want to see. 

Matt Hemmings, Chief Operating Officer at United Utilities, said: “Our teams right across the North West have been working extremely hard to make the improvements that people want to see benefit their local rivers, watercourses and bathing waters. 

“From increasing storage on sites to looking at bespoke solutions such as sustainable drainage and new innovative ways of treating wastewater to even higher standards, we are starting to see the impact our investment is making, and this is helping us make great progress in reducing spills and improving river health. 

"We are now embarking on the largest ever investment programme in our infrastructure that will see the biggest overhaul of the region’s sewer network in a century.” 

Across the region, early investment at a number of sites is delivering benefits to spill reduction. Solutions have included new storage tanks, sustainable drainage solutions and significant network enhancements.  

Schemes include: 

Cumbria - Cartmel: The existing pumping station at Cark has been transformed into a self-contained wastewater treatment works. This means the wastewater that used to come into the pumping station, which was pumped uphill to Grange-over-Sands, is now biologically treated to the highest standards in Cark before being safely returned to the environment. 

Greater Manchester - Bury: A £2.5m scheme was completed last summer to install a new underground storage tank in Sunny Bank. The area is served by a wastewater treatment works at Blackford Bridge. The new storm tank now holds 500,000 litres and is helping to reduce the number of times the storm overflow operates improving water quality at the local Parr Brook and River Roch. 

Cumbria – Cargo: A new tank was installed to provide temporary storage for spills and an additional storm tank to add a further 75m3 capacity. Spills have since reduced from 343 a year to 1 since August 2023, dramatically improving performance and an equally dramatic reduction in the impact on the environment at this small wastewater treatment works servicing 254 homes. 

Lancashire – Burnley: A £77 million upgrade to Burnley’s Wastewater Treatment Works is reducing the number of times the storm overflows are operated enhancing the water quality in the River Calder. A major overhaul of the facility saw the introduction of new treatment processes and additional storm water storage.  

Last March, United Utilities published its sector-leading 25-year road map to deliver an ambitious programme to reduce spills across the region. By 2050 the goal is to ensure that storm overflows, the relief points that prevent sewers from backing up and flooding homes and businesses in heavy rain, each operate less than 10 times a year.