Key facts
- Thames Water has amended plans for a mega-reservoir near Abingdon, Oxfordshire.
- The reservoir, named White Horse, is designed to hold 150 billion liters of water.
- The estimated cost has increased from £2.2bn to between £5.5bn and £7.5bn.
- Local councils have rejected the plans due to flood risks.
- Campaigners argue the reservoir is a flawed concept with underestimated costs.
- Customers will pay for the reservoir through their bills over 100 years.
Thames Water has revised its plans for a large-scale reservoir in Oxfordshire, England, known as the White Horse reservoir, in an effort to gain regulatory approval. The project, initially proposed in 2006, has seen its estimated cost skyrocket from £2.2bn to between £5.5bn and £7.5bn. The utility attributes the increased costs to necessary expansions of the site to 38 sq km, additional access points for construction, environmental mitigation works, and the rerouting of local waterways.
The reservoir is intended to address a projected shortfall of over 2 billion liters of water per day by 2055, driven by population growth and climate change impacts in the UK. However, the plans have faced strong opposition from local councils, including Vale of White Horse district council, Abingdon town council, and Oxfordshire county council, who cite concerns over flood risks to nearby villages. Campaigners, such as the Group Against Reservoir Development, have criticized the project as a flawed concept with underestimated costs and overstated strategic value, pointing to the potential for catastrophic consequences in the event of a dam breach on a site located on a red-rated flood plain.
Thames Water is currently conducting a targeted consultation with affected landowners and stakeholders, following a statutory public consultation that concluded in January. The company plans to submit a planning application by late 2026, with construction potentially starting in 2032 and water availability by 2040. The cost of the reservoir is expected to be borne by customers of Thames Water, Affinity Water, and Southern Water through their bills over the next century. The utility's financial health is also under scrutiny, with ministers considering its future amid significant net debt.