Worrying levels of E. coli in UK's shellfish as sewage spills into sea

With this special report, ITV News Health & Science Correspondent Martin Stew explains the hidden dangers of E.coli infecting oysters

Shellfish harvested in the UK show worrying levels of E. coli, far above what is deemed safe to eat without treatment.

Exclusive research carried out by ITV News and Watershed Investigations has found some shellfish areas have seven times the acceptable level of the bacteria.

The bug is often linked with raw sewage – and Britain has some of the dirtiest water in Europe.

Once treated, the oysters are completely safe to eat and must pass stringent safety tests, but that costs time and money.

For James Green, director of the Whitstable Oyster Company, the sewage spillages have taken a toll.

“Hand on heart the oysters are safer than they’ve ever been the amount of testing and risk assessments we do,” he said.

“The issue is the public perception and also the fact we are closed for long periods.”

His company lost £200,000 in 2021, he said, when they were forced to close for the whole summer, and they shut again in February this year.

“People come to Whitstable for oysters and they’re still eating them more than ever. If that was gone it’s like taking the fishing out of the harbour, it’s ripping that soul out of the town.”

How badly are oysters affected?

For oysters to be deemed safe enough to be shipped to the EU or eaten here without treatment, they need to have an 'A' rating – meaning 80% have less than 230 E coli per 100g.

Across a five-year period, only 6% meet that standard.

The same percentage have E coli levels so high – above 46,000 – they are prohibited from being sold even if treated.

Two shellfish areas on the south coast have recorded levels of 160,000, which is 700 times above the 'A' rating.

The oysters themselves are treated with clean water and UV before being sold. The process now takes twice as long as it used to, to ensure they pass strict hygiene tests.

Is sewage to blame?

Marine biologist Richard Stafford said it is “very likely” that sewage is the reason for such high levels of E coli.

“E coli in any of the animals we eat from the sea is never a good thing it probably means they’ve been eating raw sewage,” he said.

“It comes with the direct risks of E coli, but also risks of things like norovirus as well.”

Southern Water says it’s midway through investing £2 billion to update Victorian infrastructure.

It also points out E coli can be caused things other than sewage, including agricultural run-off and wildlife.

The problem stretches all around the UK’s shores, with 11 shellfish areas in Cornwall closed this month.

The government says it’s imposed the toughest targets ever to cut sewage spills, but the tens of billions pledged will be spread over decades.

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