Published Monday 17 November 2025
The Leader of Vale of White Horse District Council, Cllr Bethia Thomas, has written to the Secretary of State for Environment, Food and Rural Affairs, calling for urgent action on Thames Water’s controversial South East Strategic Reservoir Option (SESRO).
SESRO would create a reservoir of unprecedented scale in Oxfordshire, near Abingdon, covering up to 6.7 square kilometres and holding 150 billion litres of water. The council has previously argued the plans fail to fully consider the long-term impacts to the local community and the environment, both during a decade of construction and the irreparable damage to the countryside.
Any reservoir would also come at the expense of significant carbon emissions which the council argues would impact the district’s ability to become carbon neutral by 2045.
The letter follows a unanimous council vote on 22 October, following a motion on the growing concerns around the proposal. The letter outlines the serious concerns about spiralling costs, flawed assumptions, and the failure to properly consider alternative solutions.
When Thames Water’s Water Resources Management Plan was approved in September 2024, SESRO was costed at £2.7 billion. In its recent submission to the regulatory authority, that figure has soared to an astonishing £6.6 billion—more than double the original estimate. Cllr Thomas argues this “grotesque understatement” fatally undermines the case for SESRO and demands a full reassessment of strategic water options, including the Severn to Thames Transfer (STT) scheme.
Cllr Thomas has requested a meeting with the Secretary of State and local MPs to discuss these concerns and will continue to press for a public inquiry into SESRO.
Cllr Bethia Thomas, said: “This cost explosion changes everything. SESRO was approved on assumptions that Thames Water itself now admits were wildly inaccurate. Continuing down this path without a full reassessment would be reckless and could leave taxpayers footing the bill for a project that fails to deliver.
“Our previously expressed concerns around the safety of the proposed reservoir, the associated flood risk, and its environmental impact have still not been adequately addressed.
“We are calling on the Secretary of State to intervene, direct Thames Water to prepare a new plan with accurate financial modelling, and ensure that alternatives like the Severn Thames Transfer are properly considered. Our residents deserve transparency, accountability, and solutions that protect both their future and our environment.”
Public Consultation
Thames Water has now launched its statutory public consultation on SESRO, which runs for 11 weeks from 28 October 2025 to 13 January 2026. Residents are encouraged to have their say on the proposals.
Ends
