Water companies want bills to increase by £156 a year by 2030 to pay for upgrades and reduce sewage discharges.

The increase would allow infrastructure spending to almost double to £96bn and fund the construction of 10 new reservoirs, the water industry says.

Water industry regulator Ofwat has been asked to approve the plans.

If given the green light, water companies say the “record-breaking investment proposals” will secure the country’s water supply in the long-term.

Industry body Water UK said it is planning the “most ambitious modernisation of sewers since the Victorian era” and by the end of the decade said it could reduce leaks by a quarter compared with 2020.

It also said it would cut sewage spills into waterways by more than 140,000 each year by 2030. Water companies spilled sewage into rivers and seas more than 300,00 times in 2022.

The cost of the upgrades will be spread over decades, but if the regulator approves the plans the average annual bill will go up by £84 in 2025 rising to £156 extra by 2030.

While Environment Secretary Therese Coffey broadly welcomed the investment plans, she said Ofwat should ensure customers do not “pay the price for poor performance”

The regulator, she said, “should use the full powers we have given them on behalf of consumers”.

Ms Coffey added: “Now is the time for water companies to step up and deliver lasting changes for future generations.”

Last week Ofwat ordered water companies to pay back £114m to customers through lower bills after missing key targets.

The regulator said firms were “falling short” on performance measures around leaks, supply and reducing pollution.

The regulator said in its assessment that not one company reached the highest measure of performance.

Dŵr Cymru, Southern, Thames, Anglian, Bristol, South East and Yorkshire Water fell into the lowest category of “lagging” and the remaining 10 were rated “average”. None were considered “leading”.

If water companies fail to meet the targets it sets, Ofwat restricts the cash that they can take from customers.

All but five of the water providers reviewed will have to give money back to customers by reducing their bills in 2024-25, rather than each bill payer getting a lump sum refund.