The tender notice has been published for the White Horse Reservoir in Oxfordshire, which is the first of nine new reservoiurs that are planned for the UK.
Thames Water is leading the development of the new reservoir project, in partnership with Affinity Water and Southern Water.
The company is now seeking a main works contractor to design, build, test and commission the reservoir, which would be situated southwest of Abingdon. The proposed reservoir would have capacity to hold 150 billion litres of water and supply water across Oxfordshire and Wiltshire, through to Hampshire and London.
The reservoir is expected to generate around 1,800 jobs during construction.
Thames Water plans to submit a development consent order application to government later this year. Should the project be approved, water is set to be available for use from 2040.
Thames Water is responsible for delivering the development phase, developing the commercial model for the project and for running the procurement processes to appoint the project's main works contractor (MWC) and later, the appointment of an infrastructure provider (IP).
Thames Water is delivering the project under the Specified Infrastructure Project Regulations (SIPR) that were established and first used for the Thames Tideway Tunnel project. Under this approach a new regulated entity, known as an IP, will be established to finance and deliver the project, holding a project licence granted by Ofwat, the water industry regulator.聽Following the approach taken on the Thames Tideway Tunnel project, the MWC and IP contracts are being procured separately.
Thames Water is hosting an online applicant briefing for contractors on 11th February 2026 regarding the request to participate stage and the main works contract opportunity. Applicants wishing to attend the briefing by 12 noon on 10th February 2026.
Interested organisations then have until 24th April 2026 to submit a request to participate in the tender process. Shortlisted applicants will then be invited to submit detailed tenders.
For details see
Thames Water chief executive Chris Weston said: 鈥淭he 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.
鈥淐areers will be made and built through the reservoir鈥檚 construction with thousands of jobs created, supporting families and communities across the southeast.鈥�
Southern Water major projects director Ben Ring added: 鈥淲hite 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鈥檚 rare and sensitive chalk stream rivers 鈥� the Test and the Itchen.鈥�
Chris Taylor-Dawson, senior director for major projects at Ofwat, said: 鈥淜ick-starting the procurement process to select the main contractor is a significant milestone in the development of this important project 鈥� critical for securing our future water supply in the southeast of England.
聽鈥淏uilding 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.
聽鈥淓ngaging contractors at an early stage in the development of reservoir will tap into specialist expertise and innovative solutions 鈥� all of which can help lower costs in the longer term.鈥�
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