- Government approves national planning route for essential Oxfordshire reservoir.
- The project will secure water supply for 15 million people across the South East, including Thames Water, Affinity Water and Southern Water customers.
- The reservoir’s vital role in national water security means planning approval will sit with the Secretary of State, rather than the local planning authority.
- The decision means an independent company will be appointed to deliver the project, creating cost-savings for Thames Water customers.
- Next month Thames Water will host four community information events to share updates and speak to local people about the project.
The UK’s largest water company has secured Government backing to progress a planning application, for its 150 billion litre (150 Mm3) reservoir, situated near Abingdon in Oxfordshire.
Environment Secretary, Steve Reed, directed that the South East Strategic Reservoir Option (SESRO) project be recognised as nationally significant. Under the Planning Act 2008, Thames Water will need to seek planning approval at national level, submitting an application for a Development Consent Order in 2026.
This direction reflects the project’s national significance in securing water supply for 15 million people, with climate change and population growth all increasing pressure on water demand. The reservoir will also unlock economic growth, support new housing and infrastructure development, and create around 1,000 jobs during its construction.
The decision also enables the company to deliver the reservoir through a proven competitive financing and delivery model, building on the success of the Thames Tideway Tunnel. An independent company will be competitively selected to finance and build the reservoir, with costs recovered through customer bills over the asset’s lifetime, delivering better value for money.
Nevil Muncaster, Strategic Water Resources Director, Thames Water said: “While we've always known our proposed reservoir is of national importance, the Government’s recognition of its significance brings us one step closer to securing water supply for 15 million people across the South East.
“The right planning process and finance model is fundamental to securing our water future, delivering a cost-effective project for customers and safeguarding the environment.
"Although this project has achieved national significance, local communities remain at the heart of our plans. We're committed to engaging with local people throughout the process, which is why I'd encourage everyone to attend our information events this summer. These sessions provide the perfect opportunity to learn more about our proposals, understand the benefits and to speak to the team."
Water Minister Emma Hardy said: “South East England is projected to face water shortages by 2030. That is why the Government is intervening in the public interest to speed up the planning process and unblock new reservoirs.
“This Government will secure our water supply for future generations while protecting the environment and unlocking the building of thousands of homes as part of the Plan for Change.”
With the Environment Agency predicting more frequent and severe droughts in the UK and the Met Office confirming that spring 2025 was the warmest and sunniest on record and the driest in over 100 years for England , the country cannot afford to delay this essential water security infrastructure any longer.
The South East is already one of the most densely populated parts of the country, and population growth continues rapidly. In the last decade alone Thames Water has seen its water customers rise by a million and expects this number to climb to nearly 13 million by 2050. In addition, it’s critical that the company protects the environment, reducing the amount of water taken from precious chalk streams and aquifers, with the reservoir set to support this aim.
Without action the company forecasts a shortfall of 1 billion litres of water each day for its customers by 2050.
Community information events
Following on from its public consultation last summer, Thames Water is also set to host four community information events across Oxfordshire this July, where people will have the opportunity to meet the team, ask questions, and find out more about the project, including the planning process.
Event attendees will also be able to see a large-scale model of the reservoir and find out about the potential opportunities for communities, including, walking and cycling trails, bridleways, areas for sailing, swimming and fishing, as well as plans for new nature habitats such as seasonal wetlands, woodlands and grasslands.
The company will also hold a statutory consultation later this year, ahead of its submission for Development Consent next year.
Upcoming community information events
Wednesday 2 July 2025, 14:00 – 20:00
Milton Hill House, Milton Hill, Steventon, Oxfordshire, OX13 6AF
Saturday 5 July 2025, 10:00 – 15:00
Sutton Courtenay Village Hall, Hobbyhorse Lane, Sutton Courtenay, Oxfordshire, OX14 4BB
Thursday 10 July 2025, 14:00 – 20:00
Marcham Centre, Barrow Close, Marcham, Oxforshire,OX13 6TY
Tuesday 15 July 2025, 14:00 – 20:00
East Hanney Royal British Legion, Mill Orchard, East Hanney, Oxfordshire, OX12 0JH
To learn more about SESRO and the ongoing engagement programme and the company’s upcoming statutory consultation visit the Thames Water website.
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