There were 31,373 sewage spills over the course of the year, lasting a total of 228,098 hours, according to the Department for Environment, Food, and Rural Affairs (DEFRA)'s 'event monitoring - storm overflows' figures.

This was an 80% increase from 2022, when there were spills lasting 125,808 hours.

Analysis of the data, carried out by the Liberal Democrats, also shows the worst offending bathing sites in England - which are supposed to be unpolluted enough to swim in safely.

The party described it as "environmental vandalism" and warned families travelling to water spots over the Easter weekend would be "horrified".

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Allonby in Cumbria was the worst hit by sewage - with 4,500 hours of spillages last year.

This was followed by Haverigg, also in Cumbria and managed by United Utilities, which suffered 3,500 hours of spillages.

Middleton-on-sea in West Sussex had 3,500 hours of spillages last year, according to the data.

United Utilities, which supplies the north west of England, was the worst offending company overall - reportedly responsible for 10,467 sewage spills in 2023.

It was followed by South West Water, which registered 8,500 spills, and then Southern, Wessex, and Thames Water, which all had the equivalent of 11,000 hours of spills.

The report comes after concerning levels of E. coli were found in the River Thames, which played host to the Oxford-Cambridge Boat Race on Saturday.

One member of the Oxford team said several of his teammates suffered diarrhoea and vomiting ahead of the race.

The athletes were instructed not to swallow any water where possible and were not allowed to throw the winning cox overboard - as is tradition.

'Putting lives at risk'

Charles Watson, founder and chair of River Action UK, which compiled the data on E. coli in the Thames, told Sky News: "It is putting people's lives at risk. Since the work we did around the Boat Race, we are getting dozens of messages, mainly from parents about how kids have got really, really ill, with serious diarrhoea and vomiting."

Sewage ends up in bathing water when the system overflows due to rain and stormwater.

England's sewage system is made up of pipes that carry rainwater and wastewater from people's toilets, bathrooms and kitchens all in the same pipes.

If there's a lot of rain, there is a risk of the pipes becoming overwhelmed and sewage backing up into people's houses.

To lower that risk, instead of all the raw sewage ending up at the water treatment plant, some of it is pumped through storm overflows and into the sea or rivers.

The Lib Dems' environment spokesperson Tim Farron MP said: "Water companies must be laughing at us. These supposedly protected sites are nothing of the sort. Instead, this Conservative government has declared it open season for polluting firms to dump their filth into them.

"This national scandal cannot be allowed to continue for a moment longer."

The party is calling on the government's Scientific Advisory Group on Emergencies (SAGE) to carry out an urgent investigation.

A UK government spokesperson said water companies are subject to "stringent targets" on sewage.

"We have been clear the volume of sewage discharged into our waters is completely unacceptable and water companies need to clean up their act fast," they said.

"We are already taking tough action to hold them to account, including demanding record levels of fast-tracked investment, ensuring a 100% monitoring of storm overflows, a quadrupling of water company inspections and we are currently consulting on a ban on water bosses' bonuses, when criminal breaches have occurred."

Mark Garth, wastewater services director at United Utilities, said last year was "one of the wettest years on record in the North West".

''Whilst the current system is designed to activate during rainfall I understand and share people's concerns and the need for change and that's why we are proposing a £3bn programme to tackle storm overflows in the North West between 2025 and 2030."

He says re-plumbing the region will "take time" but data shows work is already "moving in the right direction".

John Penicud, director for wastewater operations at Southern Water, said: "Slashing the number of storm releases is top priority for us - and our customers.

"The past 18 months have been the rainiest since records began. The ground is utterly waterlogged in many areas, inundating our sewers and customers' drains and sewers.

"We're extensively relining sewers, to keep sewage in and rainwater out, and our storm release reduction pilot schemes have already proved that nature-based systems can have a real impact."

Sky News has contacted South West, Wessex, and Thames Water for comment.