We’re proposing to build a new reservoir near Abingdon in Oxfordshire.
We’ve now published our Consultation Feedback Report that provides a summary of the feedback we received during the summer 2024 public consultation. Alongside this we’ve also published our Summary Brochure and Statement of Response, showing how your feedback is playing a vital role in helping to inform the next stage of the design process.
We're confirming several changes to our proposals, based on your feedback, ongoing investigations and design work which are summarised below. During July 2025, we’re hosting a series of public information events, which will provide an opportunity to view the latest project plans and speak with the project team. To help us manage numbers, we'd be grateful if you could register your attendance in advance using the event booking link below.
Changes to our proposals
Master plan: We’re developing our master plan for the proposed reservoir site, to achieve the best balance between its operational requirements (in other words, storing and transferring water), and its future use for recreation, relaxation and as a place for nature to thrive.
Rail sidings: We’ve been engaging closely with Network Rail, whilst updating our proposals for new rail sidings to the south of the site, connected to the Great Western Main Line, which would be used to support construction of the proposed new reservoir.
Water treatment works: Working closely with Southern Water, we’ve confirmed a proposed location for a water treatment works on the site.
Intake/outfall structure: We’ve confirmed the location of the proposed intake and outfall structures on the River Thames riverbank near Sutton Courtenay.
Emergency discharge system: We’ve confirmed our preferred option for the reservoir’s emergency discharge, which is a tunnel from the reservoir to the River Thames.
Wilts & Berks Canal: We’re proposing to include a channel within the reservoir site, running along the proposed Wilts & Berks Canal alignment to make room for the future restoration of the Canal.
At the end of August 2024, we secured government approval for our Water Resource Management Plan (WRMP) and we published our final plan on 18 October 2024. We remain on track to submit an application for development consent to the Planning Inspectorate in 2026, seeking the powers to build the new reservoir.
As part of one of the early steps in the Development Consent Order process, on 28 August 2024 we requested an Environmental Impact Assessment (EIA) Scoping opinion from the Planning Inspectorate (PINS), who are acting on behalf of the government (Secretary of State for Environment, Food and Rural Affairs). EIA Scoping is an important stage in the development consent process. PINS provided their Scoping Opinion on 8 October 2024, and we are now undertaking our environment assessments based on this Scoping Opinion. You can find out more about the EIA process here.
The reservoir would be filled with water from the River Thames in the winter, when there is plenty available. When river levels drop, or demand for water increases, water would be released from the reservoir back into the river for re-abstraction downstream.
The proposed new reservoir would supply water to local customers, as well as homes and businesses across London and the South East. As well as providing a resilient water supply for the South East, the reservoir would also provide opportunities to create new habitats and increase biodiversity, as well as providing new leisure and recreation facilities. The reservoir would provide water to customers across the South East, including customers served by Affinity Water and Southern Water.
Our proposals for the new reservoir have been overseen by RAPID (Regulators’ Alliance for Progressing Infrastructure Development), a consortium of water industry regulators. RAPID has implemented a ‘gated’ regulatory process to ensure that all new strategic water supply options are considered in a fair, consistent and transparent way, and that our customers’ money is spent wisely.
More information about RAPID and the gated process can be found here, where you will also find the technical reports, additional information provided to RAPID and feedback from RAPID relating to the project.
We intend to submit an application for a Development Consent Order (DCO) in 2026, seeking permission to construct and maintain the new reservoir. If granted, construction is forecast to begin in 2029 with the reservoir planned to begin operating in 2040. The planning process will allow people to have their say on the proposed new reservoir before a final decision is made by the Secretary of State. Demonstrating that we have had regard to local and regional concerns is an important part of the DCO process. Before formally applying for a DCO, Thames Water must carry out a public statutory consultation and consider feedback.
Find out more about the DCO process in our factsheets. More information is also available on the Planning Inspectorate website.
We’ll continue to carry out more surveys and assessment work to help us refine our proposals for the reservoir. Before the submission of Development Consent Order application, there will be another opportunity to share your views on our plans.
We’re planning to hold our statutory consultation later in 2025, where we’ll be asking you for feedback on our detailed proposals.
You can stay up-to-date on all our latest news and important information relating to the project in our Document Library.
If you have any questions, please contact us.
