The opening of England's first new reservoir in over three decades has been delayed by five years, with costs more than doubling, raising concerns over water shortages and bill payer burden.

The Havant Thicket reservoir in Hampshire, secured planning approval in 2021 and began construction last year, was originally scheduled to become operational in 2029. However, regulator Ofwat has announced it will now be completed in 2034. The cost has soared from £339mn in 2022 to £822.9mn, calculated at November 2021 prices, according to Ofwat. When adjusted for inflation, the current cost of the project reaches at least £1bn.

Ofwat has opened a three-week public consultation on whether to approve the budget increase, with a final decision to be announced in December. The project adds to growing concerns that the price of UK infrastructure is spiralling out of control. Thames Water is also planning a privately financed reservoir in Abingdon, Oxfordshire, where the estimated cost has tripled to as much as £7.5bn.

The delay to the Havant Thicket reservoir's opening will exacerbate concerns over future water supplies following the hottest summer since records began, which left nearly half the population facing hosepipe bans. The Environment Agency has previously warned that England faces a potential water supply deficit of nearly 5bn litres per day if urgent infrastructure upgrades, leakage reductions and new reservoirs are not completed.