Thames Water has launched a £5.7 billion tender notice for its proposed White Horse Reservoir in Oxfordshire.
The 150 billion litre reservoir represents the largest water infrastructure investment in a generation, providing up to 271 megalitres of water per day during drought (equivalent to around 3 million baths).
It’s one of nine new reservoirs earmarked to provide water security for the UK in terms of housebuilding, economic growth and resilience against climate change.
The company is seeking a Main Works Contractor to design, build, test and commission the new White Horse Reservoir south-west of Abingdon. Water would be supplied locally in Oxfordshire and Wiltshire, through to Hampshire and London.
Mohit Farmah, Head of Procurement & Supply Chain, Thames Water, said: “We’re seeking a contractor with the vision, capability and track record to deliver one of the UK’s most significant infrastructure projects, ensuring value for money for our customers.
“This project would secure water supply for millions, protect the environment and create a space that people can enjoy for generations to come.”
Significant impact
Chris Weston, CEO, Thames Water, said: “The reservoir represents one of the most significant investments in water infrastructure the country has seen in decades.
“Once built it would be one of the largest in the country, providing water to millions, supporting new homes and development, and creating an exciting new destination where people can unwind and connect with nature.
“Careers will be made and built through the reservoir’s construction with thousands of jobs created, supporting families and communities across the South East.”
Ben Ring, Major Projects Director, Southern Water, added: “White Horse Reservoir is an essential part of our plan to keep taps and rivers flowing in Hampshire.
“Combined with our Thames to Southern Transfer pipeline, it would supply our customers with up to 120 million litres of water a day during a drought, meaning the same amount can be left in Hampshire’s rare and sensitive chalk stream rivers – the Test and the Itchen.”
Stephen Plumb, Asset Strategy and Capital Delivery Director, Affinity Water, said: “As an industry it is crucial that we are planning for resilient water supplies in the future.
“Along with reducing leakage and helping customers to reduce their demand for water we are working together, across company boundaries, to ensure there are a range of schemes to deliver and support water resources in the UK.”
Chris Taylor-Dawson, Senior Director for Major Projects at Ofwat, said: “Building on the success of the Thames Tideway project, using a competitive third-party delivery approach will boost resilience in the sector and deliver better value for customers.”
Leisure and tourism
To reflect the heritage and history of the reservoir’s location the company also unveiled its new name: White Horse Reservoir, replacing the name South East Strategic Reservoir Option (SESRO).
Beyond water storage, the reservoir aims to attract visitors and boost tourism, supporting the regional economy.
Jobs and skills
It’s anticipated around 1,800 jobs will be created, from apprenticeships to skilled trades, including ecologists, engineers, electricians, and park rangers. Thames Water is already connecting with schools, colleges and training providers to develop a ‘reservoir-ready’ workforce.
Tender notice process
Feedback gathered during Thames Water’s statutory consultation will shape its reservoir plans and inform its Development Consent Order application, ahead of submission to government later this year.
If approved, water will start flowing from the reservoir in 2040.
Details on the tender notice process and how to sign up to the Applicant Briefing can be found on the gov.uk website.
Interested organisations have until 24 April 2026 to submit a request to participate; shortlisted applicants will then be invited to submit detailed tenders.
