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Massive New Reservoir Planned to Quench South England's Thirst
12 Nov
Summary
- Thames Water plans to build a £5.5bn-£7.5bn reservoir near Abingdon, Oxfordshire
- The reservoir will be 4.5 sq miles, roughly the size of Gatwick Airport
- The project aims to provide water for 15 million people across southern England
In November 2025, Thames Water announced plans to build a new reservoir near Abingdon, Oxfordshire, as part of its South East Strategic Reservoir Option. The proposed reservoir, one of the largest in the UK, is expected to cost between £5.5 billion and £7.5 billion and will cover an area of 4.5 square miles, roughly the same size as Gatwick Airport.
The water company says the reservoir is necessary to address the growing water demand in the south of England, which serves customers for Thames Water, Southern Water, and Affinity Water. With climate change, population growth, and the need to reduce environmental impact, Thames Water believes the new reservoir is crucial to securing the region's long-term water supply.
However, the project has sparked interest and concern among local residents. Thames Water is currently conducting an 11-week public consultation on the controversial plan, which it hopes to submit for government planning consent in autumn 2026. The company acknowledges the need to address issues such as leaks and outdated infrastructure, but argues that the reservoir is essential to meet the final 20% of the region's water needs.
