Thames Water has announced the completion of a £9.7 million upgrade to Benson Sewage Treatment Works, boosting its capacity and improving environmental outcomes.

The project, which began in June 2022, was finished at the end of 2023 and has increased the site's treatment capacity by 29%, from 58 to 75 litres per second.

The enhanced capacity will significantly reduce the risk of storm overflows during periods of heavy rainfall, a key step in Thames Water's broader strategy to improve wastewater management and protect waterways. The upgrade also introduces an additional treatment stage to improve the quality of effluent released back into the river, contributing to better ecological health.

Recently, Freddie van Mierlo, MP for Henley and Thame, local councillors and Thames 21 were invited to visit the site, 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.