Thames Water has today launched an 11-week public consultation as it progresses plans for a nationally significant reservoir that will secure water supply for the South East of England, including 15 million Thames Water, Affinity Water and Southern Water customers.

With a 150 billion litre capacity, the South East Strategic Reservoir Option (SESRO) would be situated near Abingdon, providing up to 271 mega litres of water per day during drought.

Image: illustration of the proposed new reservoir in Oxfordshire

The public consultation will run for 11 weeks, from 28 October 2025 to 13 January 2026, providing a formal opportunity for people to share their views and to help shape plans. Seven in-person and two online events will take place throughout November, where communities can meet Thames Water’s team of experts to find out more and ask questions.

The consultation represents a critical step for the project, with responses directly informing the application planning consent via a Development Consent Order whichThames Water will submit to Government in Autumn 2026. Should consent be granted, water would be available for use from 2040.

The consultation follows the hottest summer on UK record and England’s driest spring in over 100 years, underpinning the urgent need for new water infrastructure.

Leonie Dubois, Head of Engagement, Land and Consents at the water company said:

“The need for this reservoir has never been more urgent. Year after year, we're witnessing more frequent droughts and prolonged dry spells across the UK, and this summer was no exception.

“Our proposed reservoir is one of the most vital infrastructure projects in the country. It will safeguard water supply for millions of people across the South East, including local communities, protecting our precious rivers and groundwater sources in the process.

“The statutory consultation is the most significant milestone in our reservoir journey to date. Public feedback will shape our application for planning consent, which we will submit to Government next year. I’d encourage everyone to look at our latest plans, attend our events and speak to the team to see what the reservoir means for them.”

Climate change is already affecting water supply. Despite recent rainfall, millions of Thames Water customers remain under a hosepipe ban as the environment recovers from the effects of prolonged dry weather.

As demand grows and more extreme weather continues, a new place to store water will be essential. In the last decade, the number of water customers Thames Water serves increased by 1 million, to over 10 million and the company forecasts a further 2 million customers by 2050.

While the water utility has committed to halving leakage in the next 25 years and plans to roll out over a million more smart meters in the next five years, Thames Water says this alone will not be enough. Without new infrastructure, the company anticipates a shortfall of 1 billion litres of water each day by 2050.

Latest proposals for the reservoir include:

• The company has enlarged the tunnel that will run between the River Thames and proposed water pumping station which would be used to transfer water in and out of the reservoir
• Is building a new lined water channel to allow for the future provision of a navigable canal.
• Plans to introduce floating solar panels within the reservoir site, which will help to reduce the emissions associated with treating and distributing water,
• Exploring potential locations for re-provision of solar farms currently situated on the reservoir site
• Identifying locations for moving species and creation of priority biodiversity areas
• Creating around 100 km of paths, bridleways, tracks and cycleways connecting local villages.

Key design features and benefits of the project

• Local supply: the reservoir would secure water supplies across the Oxfordshire and Swindon supply area, as well as regionally to London, the Thames Valley, Hampshire and Berkshire.
• Recreation: water sports, swimming, cycling, walking trails, fishing, birdwatching and nature exploration proposed on site.
• Nature: Providing over 500 hectares of green space where people can connect with nature, establishing new woodlands, wetlands and diverse habitats to enhance biodiversity.
• Economic: create opportunities for local businesses throughout construction, creating around 1,000 jobs and apprenticeships.
• Transport: building a new 3km access road to the reservoir which will link to the A415 and a new and improved road between East Hanney and Steventon.
• Water: extensive flood management features to ensure local flood resilience is not compromised and where practicable enhanced.

Thames Water is encouraging anyone with an interest in the project to attend one of the seven in-person or two virtual events taking place during November.

To find details of the events click here.

People can have their say on the project by giving written feedback in one of the following ways:

Fill in the online feedback form available at the consultation website 

Emailing the dedicated consultation response email address at This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Filling in one of the printed feedback forms and posting it free of charge to FREEPOST SESRO CONSULTATION. Feedback forms will be available to collect from public information events, from various locations within the community or by requesting that one to be posted by the project team. Pre-addressed envelopes are available where there are printed feedback forms. No stamp is needed.

Deadline for the receipt of all responses in writing is11.59pm on 13 January 2026.

Click here to visit the SESRO website.