AECOM to Design £340m Upgrade of Thames Water's Oxford Sewage Works

AECOM has been appointed design partner for a £340 million upgrade of Thames Water's Oxford Sewage Treatment Works, a scheme intended to expand capacity and improve the quality of effluent discharged into the River Thames. The infrastructure firm was appointed by contractor Murphy as exclusive design partner for the project, part of Thames Water's capital works under the UK's current Asset Management Period, known as AMP8. The upgrade will increase treatment capacity by around 40 percent to support population growth in Oxfordshire while raising the environmental performance of the site.

The scheme extends beyond raw capacity. Alongside the treatment expansion, the works include upgrading power supplies, increasing storm tank capacity and raising sewage treatment flows, measures aimed at making the facility more resilient. Thames Water framed the investment as improving the long-term resilience and environmental performance of its wastewater network for a growing community.

The environmental dimension centres on what leaves the plant. By improving effluent quality at the end of the treatment cycle, the upgrade is designed to better protect the River Thames, and the expanded storm tank capacity is intended to reduce storm overflows. That focus is significant given the scrutiny UK water companies have faced over sewage discharges into rivers and waterways, which has made storm-overflow reduction a prominent environmental and regulatory issue.

 

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Thames Water's senior project manager, David Mayfield, said the upgrade represented a significant investment in the resilience and environmental performance of its wastewater network, and that working with AECOM and Murphy would deliver a future-ready facility that safeguards waterways and provides a resilient service with fewer storm overflows. The project builds on prior collaboration between the parties, including AECOM and Murphy's earlier work with Kier on Thames Water's Deephams Sewage Treatment Works, one of London's largest wastewater plants.

The upgrade forms one strand of a broader wave of UK water infrastructure investment under AMP8, the regulatory period during which water companies are required to fund improvements to service, resilience and environmental standards. Beverley Stinson, chief executive of AECOM's global water business, said the firm would draw on AI-enabled design tools to deliver more efficient and sustainable infrastructure, positioning technology as central to how the expanded capacity is delivered.