Untreated sewage was discharged into England’s coastal bathing waters for more than 160,000 hours last year, according to figures collated by the Liberal Democrats.
Environment Agency figures on 2021 discharges show that water companies released raw sewage 25,000 times into designated bathing waters off the English coast.
The bathing water designations – which were created by the EU – are designed to highlight the country’s cleanest and safest waters for the public.
The quality of the water is identified on signs at the beaches, ranging from excellent to poor.
The longest discharges into bathing waters were carried out by United Utilities, which released untreated sewage into sea-swimming spots in the north west for almost 75,000 hours.
The company’s worst-hit bathing water site was Morecambe South beach.
Tim Farron, Westmorland and Lonsdale MP and also Lib Dem rural affairs spokesman, said: “It is now or never to save families from swimming in sewage-infested waters this summer.
“Children should be free to enjoy Britain’s great coastlines and lakes, yet Conservative ministers are letting water companies get away with shameful sewage dumps. This is an environmental scandal.”
Coun Dave Brookes, Lancaster City Council cabinet member with responsibility for environmental services, said: “Morecambe Bay is an internationally important site for wading birds, as well as a seaside resort and a centre for a growing number of water-based activities.
"With the prospect of Eden Project North just around the corner, we can expect to see many more visitors coming to the town to enjoy its sandy beaches.
“These latest reports are very concerning and we will continue to make the strongest possible case to both United Utilities and the Environment Agency that the cleanliness of our bathing waters should be a top priority.”
A United Utilities spokesman said: “The north west coastline has seen billions of pounds of water company investment over the last 30 years meaning that bathing waters are now cleaner than they have ever been.
"For example, since 2018 we have spent £80m upgrading our treatment works at Morecambe and building more storm water storage at Carnforth and both of Morecambe’s bathing waters are now classified as Good.
"Across the region, 93 per cent of bathing waters were classified as Good or Excellent in 2021 and all met the designated minimum standards.
“We are already committed to a programme of action for further improvements, building on this environmental achievement, and we are spending £230m over the next three years to reduce the impact of storm overflows.”