Bathing waters across the UK are awash with pharmaceuticals, pesticides, industrial chemicals, harmful bacteria and genes that can create superbugs resistant to antibiotics, including medicines used as a last line of defence, Watershed has uncovered.

In collaboration with the University of York, citizen scientists and Surfers Against Sewage, hundreds of samples were taken from river and lake swimming sites over a week during the summer and a wide range of pollutants were detected, including levels of E.coli up to 22 times higher than would be deemed safe in the US, banned ‘forever chemicals’ that have been linked to cancer, and pharmaceuticals used to treat diabetes and seizures.

The work was the lead story on ITV News and was covered in The Times and the i Paper.

Results can be seen on the Watershed Pollution Map.

E.coli was found above the US safety threshold of 235 colony forming units per 100 millilitres at more than half the sites tested, with Frensham Great Pond in Surrey recording the highest with 5,200, followed by swimming spots on the rivers Dart (3,400cfu/100ml), Ribble, Wharfe, Nidd, Wolvercote and Thames. 

Some 57% of the bathing waters samples exceeded the E. coli safety thresholds used in the US and New Zealand. The UK’s E.coli safety threshold is much higher, allowing 900 cfu/100ml. However it is calculated across more samples per site and so can’t be applied to the project’s samples. 

Genes were detected in the bathing waters that, if taken up by harmful bacteria or viruses, can create superbugs resistant to antibiotics. Some of the genes identified could make critical last-line-of-defence antibiotics ineffective, with potentially disastrous consequences.

The highest number of resistance genes were detected at bathing sites on the rivers Dart, Nidd, Ribble and Wye.

Antibiotic resistant infections have been rising steadily, according to the The UK Health Security Agency (UKHSA). There were an estimated 66,730 serious antibiotic resistant infections in 2023, compared to 62,314 in 2019, with the majority caused by E.coli. 

The UKHSA says “Antibiotic resistant bacteria of any kind are less likely to respond to treatment, causing serious complications, including bloodstream infections, sepsis and hospitalisation. People who get a bacterial infection that is resistant to one or more antibiotics are more likely to die within 30 days compared to those who have an antibiotic sensitive infection.” 

Professor Alistair Boxall, from the University of York where the samples were analysed, said:  “The warning message is that at some locations we were detecting a range of resistance genes some of which are associated with last resort antibiotics. If you’ve got a situation where swimmers are swimming in a system with bacteria, some of which might be pathogenic, and resistance genes, there is potentially a risk of people getting sick and if the resistance genes are acquired by the pathogens, it will make those infections less treatable.

“We think that when you’ve got chemicals, such as antibiotics, in the mix, they can encourage the transfer of the genes between bacteria. The worst case scenario is probably where you have antibiotic resistance genes, pathogens and chemical pollutants mixed together — they would work together to increase the risk of people being exposed to resistant pathogens.”

The Environment Agency tests bathing waters around 16 times between May and September for E.coli and enterococci and classifies the sites anywhere between excellent and poor, based on the results. 

But Will Gaze, professor of microbiology at the European Centre for Environment and Human Health at the University of Exeter, said the study showed that “there are other bacterial pathogens in the waters… that are causing widespread infections in humans… the reality is that sewage contains this vast complexity of chemicals and bacteria and viruses and fungi.

The sampling found “really important human bacterial pathogens, resistant mechanisms for critically important antibiotics which are used to treat those pathogens, and antibiotics in rare occasions that are near the levels that may be contributing to resistance in the longer term, so it is all rather concerning,” said professor Gaze.

Pollution from farms and sewage from wastewater treatment works are major sources of resistance genes, pathogens and contaminants. Genes in the River Wye could be traced back to pigs. 

Dr John Wilkinson, from the University of York said “The amount of antimicrobial use in pigs is high, which means you’ve got resistance selection pressure in the bacteria when they’re exposed to these antimicrobial chemicals in this situation. Genes which confer this resistance can then reach the aquatic environment via runoff from slurry that’s been spread on fields or via runoff from a farm where antimicrobials have been given to the pigs.”

Dr Wilkinson says sewage spills into rivers are “a real worry because there’s a lot more of the chemicals and a lot more of the pathogens coexisting in untreated sewage” although “they’re found in treated sewage too”.

The River Cam in Cambridge and the Ribble at Edisford Bridge were found to have the highest number of pharmaceuticals, pesticides, metals and industrial chemicals in them, and the Mixed Pond in Hampstead Heath had the highest number of PFAS forever chemicals in its waters, although at low levels. One PFAS called PFOA, that has been categorised as a human carcinogen by the World Health Organisation, was found in 95% of bathing waters tested.  

None of the chemicals  were found at concentrations that are known to affect public health, but there is concern among scientists about the unknown effects of these chemical cocktails on wildlife and people.

“The concentrations of chemicals are really low and very unlikely to cause health impacts in the short term,” says Boxall but, “some of the chemicals are known to cause impacts in the longer term from prolonged exposure which is more concerning.

“The Environment Agency monitoring of bathing water sites focuses on bacteria. Many of the chemical pollutants occur all the time in river water even when bacterial levels are low. The current monitoring approach won’t protect swimmers from the chemical exposure.”

Giles Bristow, chief executive at Surfers Against Sewage said “The saturation of our waterways with sewage pollution is well known, but these findings demonstrate there’s a lot more than human waste lurking beneath the surface. With regulators and the government turning a blind eye, citizen scientists have acted to lift the lid on the toxic chemical cocktail that’s leaching into our rivers, lakes and seas. 

“The true environmental and health impact of this slurry of pollutants, which include banned and carcinogenic forever chemicals, are still being revealed and yet government is allowing them to swamp the wild waters where we surf, swim, and where fragile ecosystems are on the brink of collapse. Bathing regulations urgently need wholesale reform – the government has taken the first step by consulting on this issue, now it must deliver. 

“These disturbing findings must spark the end of the era of inadequate water quality testing. The public deserve a full picture of what’s coursing through the UK’s waters. Citizen scientists have lifted the lid, now it’s time to flush the pollutants out of our rivers, lakes and seas.”

A government spokesperson conceded that “too many of our popular swimming spots are polluted” and said it is committed to “reforming the water system to help clean up our rivers, lakes and seas for good.

It is currently consulting on reforms to bathing water regulations to “allow greater testing flexibility at bathing water sites and introduce multiple testing points, in the first shake up in the regulations for over a decade.

“We are also developing an ambitious programme to better protect our natural environment, including how best to manage chemicals such as PFAS.”

An Environment Agency spokesperson said it takes more than 7,000 samples at 451 bathing waters during the bathing season and that these samples undergo rigorous testing to provide people with water quality information to make informed choices on when and where to swim. 

“We will continue to work closely with the agriculture sector, water companies and local communities to understand how pharmaceutical compounds enter our water environment and to ensure the highest standard of bathing waters for the public.”  

rachel.salvidge@watershedinvestigations.com