Previously known as South East Strategic Reservoir Option (SESRO)
Since our statutory consultation, which ran from October 2025 to January 2026, we've been reviewing the feedback and have continued to develop our reservoir designs. We’ve also carried out more detailed planning to understand how the reservoir could be built, including the types and quantities of materials needed, where different construction activities would take place, when they would happen, and how workers, equipment, and materials would move around the site.
We’re engaging with local authorities and National Highways to develop mitigation measures for construction traffic where practicable and this work will feed into our traffic and transport assessment. The final traffic forecasts and assessments will be included in our Environmental Statement which will be submitted with our Development Consent Order (DCO) application later this year.
During our statutory public consultation, we also proposed relocating three solar farms, currently located on land that would be needed for the reservoir, to the west of the reservoir site. We've considered all of the feedback received, carried out further engagement with stakeholders, and have decided to remove this proposal from our plans. We will continue to include floating solar on the reservoir itself, as previously planned. You can read more on project progress in our latest newsletter below.
We’re proposing to include additional access points around the site (up from six to 17) to carry out construction and environmental mitigation works (such as new habitat creation) in specific areas.
As well as engaging with National Highways and statutory authorities on these, we're also carrying out a targeted consultation with affected parties. The feedback we get, along with feedback gathered during our statutory public consultation last year, will help inform our reservoir proposals as we prepare to submit our application for development consent later this year. You can read more about our proposed changes to construction access points in our factsheet and map book below.
As our reservoir proposals have evolved, so too has their potential legacy. The proposed reservoir is a critical drought insurance policy for the next century and beyond, while also being designed as a place for people to use and enjoy for many years to come.
White Horse Reservoir would help supply water to around 15 million people across the South East. It would play a critical role in tackling expected water shortages and would also bring lasting local benefits, including new spaces for nature, leisure, and community use.
The name, White Horse Reservoir, gives the project a new identity that better reflects the crucial role it would play in shoring up water supply, as well as the wider benefits it would deliver for future generations.
It is the same project, with the same vision, but with a name that will help people recognise it more easily. The name White Horse Reservoir roots the project in local heritage and the natural world around us. Just as importantly, the project's strapline - " a space for nature, a place for people" - highlights where its strengths lie, reflecting our ambition to create a reservoir that benefits both the environment and local communities. Further information about the project can be found below and in the document library.
Thanks to everyone who shared feedback during our statutory public consultation which ran from 28 October 2025 to 13 January 2026. Over 1,200 of you attended our nine events, both in person and online. We’re grateful to everyone who took the time to give feedback - it really does make a difference. We’ve carefully analysed all the feedback received during the consultation, and your views are helping us refine the proposed design and shape any mitigation measures.
We’re preparing a consultation report which will summarise the feedback we have received from stakeholders and outline how the proposals have developed as a result of engagement and consultation activities, as well as ongoing design development. This will be submitted, alongside all other relevant documentation required to support our Development Consent Order (DCO) application, in late 2026. This application will be made to the Planning Inspectorate, which will examine the application on behalf of the Secretary of State for the Department for Environment, Food and Rural Affairs (DEFRA).
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, including technical reports, additional information provided to RAPID, and feedback from RAPID relating to the project can be found here.
Our presence on and around the site has increased as we continue our programme of ecology, archaeological surveys and ground investigations. These surveys are an essential part of understanding the local environment and helping to shape the project design. Together, this work is building a robust evidence base to guide the next stages of assessment, mitigation planning, and the Environmental Statement that will support our Development Consent Order application in late 2026.
For the latest updates on the White Horse Reservoir project you can sign up to receive our e-newsletters below.
We’re planning to submit our application for a Development Consent Order (DCO) later in 2026, seeking permission to construct and maintain the new reservoir. If granted, the main phase of 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. Find out more about the DCO process in our factsheets. More information is also available on the Planning Inspectorate website.
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