A sewage treatment works in south Oxfordshire has been given a £9.7 million revamp to reduce untreated water from being discharged in the river and to meet growing demand.

Thames Water says that the upgrade to Benson Sewage Treatment Works will reduce the need for storm overflows during heavy rainfall and produce a "higher quality of effluent" – untreated water that is discharged into the river.

The site near Wallingford has increased its capacity by 29 per cent, from 58 to 75 litres per second.

This is part of Thames Water’s plan to upgrade 250 of its wastewater sites, including those in Oxford, Witney, Cholsely and Dorchester, to help manage demand due to population growth and climate change.

It comes as the water company has been under fire for sewage spills and for being heavily indebted. 

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Liberal Democrat MP for Henley and Thame Freddie van Mierlo, councillors representing Benson & Crowmarsh Ward and the Thames 21 charity were invited to visit the site.

Mr van Mierlo said: “I welcome all investment in the constituency to increase capacity to handle sewage and decrease storm discharging.

“Clearly far more needs to be happening across Henley and Thame, and I will be working actively with partners to achieve that”.

District councillor Andrea Powell, who represents the Benson & Crowmarsh ward, said: “It was very interesting and reassuring to see the significant investment made by Thames Water in Benson Sewage Treatment Works.

“We know how much local people care about river pollution and the effective treatment of increasing levels of sewage caused by major housing developments in the area.”

District councillor Sue Cooper said: “Having visited the Benson Sewerage Treatment Works almost 40 years ago it was really interesting to see the extra capacity and level of sophistication.

“I know our local residents are keen to know that there is sufficient capacity there to cope with all the new housing in our area so it will be good to be able to reassure them.”

The upgrade began in June 2022, and was completed at the end of 2023.

Awwab Abbasi, project manager at Thames Water said: “We are pleased to have completed our upgrades at Benson sewage treatment works to improve our site for residents, businesses and the environment in the area.

"As custodians of this important infrastructure, we need to ensure our sites are resilient to the pressures of climate change and population growth so we can continue to provide reliable services to our customers.  

“This upgrade to our network will help protect customers and the health of the rivers and waterways.

"We believe all discharges are unacceptable and we are committed to seeing healthy and thriving waterways, however we can’t do it alone.

"While we play an important role in this, we aren’t the sole custodians of river health. We need everyone working together to help our waterways thrive.”  

South Oxfordshire District Council voted unanimously to declare no confidence in Thames Water and called on the government to bring the company into special measures at its last council meeting on Thursday, October 24.

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About the author  

Esme is a Local Democracy Reporter covering politics, planning and council meetings across the county. 

She joined the Oxford Mail in October 2024 after completing a Master's in Journalism at the University of Sheffield.

Esme achieved a BA in History at Cambridge University before going down the journalism path.

She can be found on X by searching @esme_kenney.