Thames Water has hosted a visit by Freddie van Mierlo, MP for Henley and Thame, local councillors and Thames 21 to view a recently completed £9.7 million upgrade project at its Benson Sewage Treatment Works.
The upgrade has increased the site’s capacity by 29% which will reduce the need for storm overflows during heavy rainfall and produce a higher quality of effluent.
The project is part of Thames Water’s plan to upgrade 250 of the company’s wastewater sites to help manage demand due to population growth and climate change.
Work on the project, which began in June 2022 and was completed at the end of 2023 , has increased the site's capacity by 29% from 58 to 75 litres per second. The increase in treatment capacity will greatly reduce the risk of storm overflows during spells of heavy rainfall. The upgrade also includes an additional stage in the treatment process which will help to return a better quality of effluent to the river.
Thames Water invited Freddie van Mierlo, MP for Henley and Thame, local councillors and Thames 21 to visit the site to showcase the improvements and demonstrate the process of treating wastewater every day.
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.”
Freddie van Mierlo MP for Henley and Thame said:
“I’m grateful to Thames Water for showing me around Benson Sewage Treatment Works and walking me through the upgrades that have taken place there. 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”.
The upgrade of Benson STW is part of Thames Water’s plans to improve 250 of its wastewater sites to help manage the effects of population growth and climate change. These include nearby sites at Cholsely and Dorchester and others in Oxfordshire including its sites in Witney and Oxford.
With the UK government demanding a 50% reduction in storm overflow spills by 2029, the era of reactive management is over. Speaking in the House of Commons on 21 July 2025, then environment secretary Steve Reed said, “This Government will cut water companies’ sewage pollution in half by the end of the decade.”
ERG, the leading supplier of odour control systems and industrial gas cleaning & thermal systems, has been awarded the coveted King’s Award for Enterprise.
Welsh Water’s new artificial intelligence-driven tool, ORAI, has been shortlisted for three categories at the prestigious British Data Awards 2026 – underscoring the company’s commitment to using cutting-edge technology to deliver better outcome for customers.
Barhale has completed work on two separate Rapid Action Taskforce Spills projects it is carrying out for Severn Trent.
Hear how Scottish Water has completed its £235 million Ayrshire Glasgow Resilience Project - customers across Greater Glasgow, Ayrshire and East Renfrewshire will now benefit from a more secure and resilient water supply.
Hear how United Utilities is accelerating its investment to reduce spills from storm overflows across the Northwest.
Find out more about the remarkable career opportunities on offer at WSP - scroll down to watch the inspirational video.