Liberal Democrat councils have been urged to launch a series of inquiries into sewage-dumping as the party claimed there were nearly 15,000 spills in the areas where it gained formerly Conservative seats.

Sir Ed Davey has told local authority leaders to investigate the impact of the issue by requesting evidence from Ofwat, the Environment Agency, citizens and charities.

His party won control of 12 councils, largely at the expense of the Tories, at last week’s local elections.

The Conservative government is totally failing to listen to communities who want to see action taken now to tackle this sewage scandal

The party claims sewage was dumped 14,843 times over 130,000 hours last year in these new local authority areas, with South Hams experiencing the most spills at 5,047 discharges in 2022, followed by Teignbridge with 3,240 and Mid Devon with 2,088.

The inquiries would request oral and written evidence from Ofwat and the Environment Agency, environmental charities and citizens on the impact sewage dumping is having on local rivers, beaches and wildlife, according to the Lib Dems.

It comes after Financial Times analysis of water and sewage firms’ accounts suggested that company dividends increased from £540 million in 2021 to £1.4 billion in 2022.

Sewage-dumping was a key electoral battleground in the run-up to the local elections last month and has featured heavily in the Lib Dems’ campaign, to which they partly attribute their successes in some formerly Tory areas.

A Conservative Party source hit back at the party’s latest attack, claiming: “More press releases and still no plan from the Liberal Democrats.

“Promising to stop sewage overnight whilst touting a sewage tax that would take 500 years to pay for it is an uncosted political game and a recipe for sewage backing up into people’s homes.”

The Lib Dems have called for a tax on water companies to clean up the most polluted rivers and a ban on bonuses for sewage bosses.

Sir Ed said: “People are furious with Conservative MPs for voting time and again to allow water companies to get away with dumping their filthy sewage into our rivers, chalk streams and beaches.

“The Conservative government is totally failing to listen to communities who want to see action taken now to tackle this sewage scandal.

“I am asking Liberal Democrat councils to take matters into their own hands and launch inquiries into the impact of sewage dumping.

“This will give local people a chance to make their voices heard and put pressure on the Conservative government to finally act to tackle this sewage scandal.”

A Department for Environment, Food and Rural Affairs spokesman said: “Our new plan for water sets out the increased investment, tougher enforcement and tighter regulation to tackle every source of river pollution, including from storm overflows, agriculture, plastics, road run-off and chemicals.

“We have recently confirmed over £1.6 billion of new investment will be directed into vital infrastructure to improve water quality and secure future water supplies.

“It is completely untrue that the Government or MPs ‘voted to allow water firms to continue sewage dumping’ as part of the Environment Act. Discharges that were unlawful prior to the Act are still unlawful and the government recently announced that its target to reduce storm overflows will be enshrined in law.”