One of London’s most popular outdoor swimming spots has seen a 1,188.8 per cent surge in a strain of bacteria that can cause life-threatening infections and severe food poisoning.
New research has revealed that the levels of E coli in Hyde Park’s Serpentine Lido dramatically increased between 2023 and 2024, while samples taken at Hampstead Heath Mixed Ponds also increased by 230 per cent during the same period.
E coli is a type of bacteria that lives in the intestines of humans and can cause diarrhea, stomach cramps, fever and can lead to kidney failure.
The figures come after wild swimming has surged in popularity across the UK since the Covid-19 pandemic, but growing concerns have emerged over its safety due to the polluted nature of our waters.
In 2023, the Serpentine Lido had an E coli count of 45 which had increased to 580 in 2024, while figures that indicate faecal contamination in the water also increased by 1,085 per cent.
Despite this, it has been recently rated as “Sufficient” by the Environment Agency, which means the water meets the minimum standard required for bathing water.
In response to widespread public anger, the government announced reforms to bathing water regulations earlier this year, which include changes to designation criteria for future sites, more flexible seasons, and an expansion of the legal definition of “bather”.
To monitor water quality, the Environment Agency said it plans to take more than 7,000 samples at 451 designated bathing sites across England throughout this year’s season.
Results from lab tests will be uploaded on to Swimfo to help the public decide where to swim, and will be ultimately used to classify the quality of each site as “excellent”, “good”, “sufficient” or “poor” at the end of the season.
Professor Davey Jones, a soil and environmental scientist at Bangor University, stressed the need for more rigorous monitoring of pathogens in water including viruses, which are currently not routinely tested for.
“They’re one of the biggest threats to human health,” he said.
“Some pathogens, like E coli 0157, can enter groundwater through agricultural runoff and pose serious health risks, even in small amounts. As recreational water use increases, especially in urban settings like London, it’s vital we broaden our testing frameworks to include viral contaminants.”
Amelia Hornsby, from the Bathing Mobility Advisory Service who conducted the analysis, commented: “Water quality is a key indicator of environmental health and public safety.
“Consistently high standards are essential not only for protecting ecosystems, but also for ensuring safe and enjoyable access to our natural waters for local communities and visitors alike.”
