Abingdon Reservoir cost forecast rises to £6.5bn

The Abingdon Reservoir cost forecast has risen to a range of £5.5 to £7.5 billion, with customers likely paying via their bills.

Abingdon Reservoir cost forecast rises to £6.5bn

Thames Water says the Abingdon Reservoir cost has jumped from the initial £2.2 billion estimate to a revised range of £5.5 billion to £7.5 billion. Customers of Thames Water, Affinity Water and Southern Water will pay the bill through their charges, with around £5 a month added by 2040, subject to the final design and market conditions for financing costs.

The update appears in the Gate Three report ahead of a planning application due next year. RAPID, a joint regulator made up of Ofwat, the Environment Agency and the Drinking Water Inspectorate, will review the report. Thames says the project still offers the best value and will provide security of supply for about 15 million people.

Rising costs shift risk onto households at a time when utility bills are already under pressure. The jump from a £2.2 billion estimate to a multi‑billion forecast invites questions about how such projects are planned, budgeted and scrutinized.

Regulators say they weigh reliability against affordability. The autumn report on alternatives could reveal cheaper paths or new constraints, and public reaction will shape the politics around water infrastructure.

Highlights

The next steps will test whether price and reliability can align.