Teddington Direct River Abstraction (TDRA)
A drought resilience project for London.
South East Strategic Reservoir Option (SESRO)
We’re proposing to build a new reservoir near Abingdon in Oxfordshire.
Take a tour of our proposed new reservoir
Project update
Thank you to everyone who took part in our summer 2024 public consultation on our emerging proposals for the new reservoir.
Customer and community feedback is at the heart of our plans. We're engaging stakeholders and local communities as we go, to understand priorities and gather important information and feedback which will all be considered and will help to shape our proposals.
We had over 1,500 responses to our summer 2024 consultation and more than 1,200 people attended our programme of local community information events. The feedback gathered, which is being independently verified by Ipsos, will play a vital role in helping to inform the next stage of the design process.
We will provide a formal response to the public consultation early next year, and local communities and stakeholders will be invited to have their say on the revised proposals for the reservoir next summer.
At the end of August 2024, we secured government approval for our Water Resource Management Plan (WRMP). 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 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. You can find out more about the EIA process here.
Why do we need a new reservoir?
Our water resources are under pressure. For the sake of the environment and our future water supplies, we must start planning to address those risks.
We’ve assessed a wide range of options, including tackling leaks, making the best use of our water resources and developing new sources of water including water recycling, regional water transfers and reservoirs. Given the scale of the water resources shortfall, we’ll need a combination of demand reduction and new water sources.
Working with Water Resources South East (WRSE), the technical assessments and modelling that have been carried out show that a new reservoir forms an integral part of the proposed plan for the South East region.
We’ve taken into account feedback from regulators, stakeholders and our customers and carried out further modelling work. This has concluded that a 150 million cubic metres (Mm³) reservoir is a best value solution.
The Secretary of State for Environment, Food and Rural Affairs, the Rt Hon Steve Reed MP, approved our Water Resource Management Plan (WRMP) in August 2024. The decision to approve the plan follows extensive public consultation over a two-year period. On reaching the decision to approve our plan, the Secretary of State concluded that there is a strategic need for SESRO.
How would it work?
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.
Developing our proposals
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.
Securing planning consent
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 public consultation and consider feedback.
Find out more about the DCO process in our factsheets in the Document Library.
More information is also available on the Planning Inspectorate website.
What’s happening next
To inform the design proposals for the reservoir, we’re carrying out a range of surveys to build a thorough understanding of the local geology. This includes ground investigations and a clay compaction trial to understand how the strength and water content of the local Kimmeridge clay changes when it’s compacted.
In March 2024, we were granted consent by the Vale of White Horse District Council to carry out the clay compaction trial on land to the south of Hanney Road, at Cow Common (OX13 6AP).
We started work on site in July 2024, and depending on the weather and ground conditions, our work will take up to six months. The first phase of our work saw the creation of a temporary access road from the Hanney Road to reach the site, the removal of site topsoil and the erection of a welfare unit and site cabins.
During September and October 2024, we’ll be excavating the clay from the site which will be used to create test embankments up to three metres high. This will help to inform our understanding about how the strength and water content of the local clay changes when compacted.
Once completed, we will dismantle the embankments, and the ground will be reinstated.
You can find out more about the clay compaction trial and our ground investigations here.
Other projects
Water transfer projects
Considering water transfer options.