The White Horse Reservoir (formerly known as SESRO)
Thames Water is proposing a new large reservoir on land west of the A34, Abingdon.
The proposal, now titled the White Horse Reservoir (formerly known as the South East Strategic Reservoir Option, or SESRO), is considered a ‘Nationally Significant Infrastructure Project’, which means it will be determined by a government appointed Planning Inspector.
The South Oxfordshire is impacted proposal. Whilst the main body of the reservoir is sited in neighbouring Vale of White Horse district, some parts of the Draft Order Limits which cross into the district around Culham.
Current status
The next major milestone for the proposed reservoir is the submission of Thames Water’s Development Consent Order (DCO) application to the Planning Inspectorate, which is currently expected in November 2026.
- The project is currently in the pre-application stage.
- Once the DCO application is submitted, the Planning Inspectorate has 28 days to decide whether to accept it for examination.
- If accepted, the project moves into the Pre-Examination phase, when local authorities, parish councils, community groups and residents can formally register as Interested Parties and submit representations.
- This will then be followed by a detailed public examination before a recommendation is made to the Secretary of State.
You can find further information on the developer’s project website.
Publications
South Oxfordshire District Council submitted its consultation response on Thames Water’s proposed South East Strategic Reservoir Option (SESRO) in January 2026.
South Oxfordshire District Council also set out its objections in a formal letter to the Secretary of State for Environment, Food and Rural Affairs in December 2025. The letter from the Council Leader, Cllr Maggie Filipova-Rivers, called for clarity regarding how emergency discharge from the proposed Abingdon reservoir will be managed. Cllr Filipova-Rivers also called for a firm commitment to providing the resources necessary to deal with any such discharge before the government considers any further consent to the project.
The letter followed a debate on the topic at the full council meeting on Thursday 11 December – where a motion was raised and approved expressing concerns about the proposed reservoir’s Emergency Discharge facility.
Press releases
December 2025: https://www.southoxon.gov.uk/sesro/council-leader-calls-for-answers-on-emergency-discharge-from-the-proposed-abingdon-reservoir/
March 2022: https://www.southoxon.gov.uk/planning/reservoir-plans-should-be-urgently-reviewed/
