Thames Water Launches £5.7bn White Horse Reservoir Project in Oxfordshire

Thames Water has begun the procurement process for the construction of the White Horse Reservoir in Oxfordshire, a £5.7 billion project that forms the first of nine new reservoirs planned across the UK.

The reservoir, being developed in partnership with Affinity Water and Southern Water, will be located southwest of Abingdon and is designed to store 150 billion litres of water, supplying communities across Oxfordshire, Wiltshire, Hampshire, and London. The project is expected to create approximately 1,800 jobs during construction.

Thames Water will submit a development consent order application to the government later this year, with the reservoir expected to be operational by 2040 if approved. The company is responsible for overseeing the development phase, designing the commercial model, and running procurement processes to appoint both a main works contractor (MWC)and an infrastructure provider (IP) under the Specified Infrastructure Project Regulations (SIPR), a model first used for the Thames Tideway Tunnel.

An online briefing for interested contractors will take place on 11 February 2026, with registration open until noon on 10 February. Requests to participate in the tender process must be submitted by 24 April 2026, after which shortlisted organisations will be invited to submit detailed bids.

Thames Water CEO Chris Weston described the reservoir as “one of the most significant investments in water infrastructure in decades,” highlighting its role in supporting homes, development, and creating a community-focused natural space.

Southern Water’s Major Projects Director, Ben Ring, emphasised that the reservoir, combined with the Thames to Southern Transfer pipeline, would deliver up to 120 million litres of water per day during droughts, helping preserve Hampshire’s sensitive chalk stream rivers.

Ofwat Senior Director for Major Projects, Chris Taylor-Dawson, added that engaging contractors early in the project would encourage innovation and help lower costs while boosting resilience and long-term value for customers.