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United Utilities has marked a significant milestone in its £50 million modernisation of Southport's Wastewater Treatment Works.
Construction and installation of the reinforced walls for a large stormwater storage tank are now complete on site. Testing and further engineering will continue through the summer, ahead of the tank entering service in late 2026.
The tank can hold up to 4,500m³ of stormwater during heavy rainfall—equivalent to 2.5 Olympic-sized swimming pools or 30,000 bathtubs—bringing phase one of the scheme to a close.
A second phase, expected to be finished by summer 2029, will further increase the site's capacity to treat more wastewater during periods of intense rain.
The upgrade is designed to enhance water quality along the Sefton Coast by reducing how often storm overflows operate during wet weather.
Steven Kenyon, County Business Lead for United Utilities in Merseyside, said: "We are committed to continuous improvement to our infrastructure, and upgrades to Southport's wastewater treatment works are a priority.
"From increasing storage on site 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. This is helping us make great progress in reducing spills and improving water quality.
"We continue to review our network and sites across the county to identify where we can make further improvements that help reduce the number of times storm overflows need to operate."
The Southport scheme forms part of United Utilities' £13 billion Big North West Upgrade. Over the next five years, this investment programme will deliver new infrastructure, improve water quality, replace ageing water pipes, reduce leakage to its lowest-ever level, and protect more than 500km of rivers and bathing waters—cutting the use of storm overflows by 60% over the decade to 2030.
The project is being delivered through United Utilities' Enterprise delivery model, which brings together seven design and construction partners, plus United Utilities, into one integrated team.
