Community

E. coli levels surge over 1,000% at Serpentine as wild swimming popularity soars

Sunday, 25 May 2025 12:17AM UTC

As wild swimming gains popularity across the UK, new data reveals a dramatic rise in harmful bacteria such as E. coli at key outdoor swimming sites, raising urgent concerns over water quality and public health risks.

It's a trend that has gained traction across the UK, as more and more people are opting for wild swimming as a health-conscious alternative to traditional exercise. However, alarming data reveals that this surge in popularity has been accompanied by a significant and disturbing rise in harmful bacteria levels in some of the country's most cherished outdoor swimming locations.

Recent statistics indicate a staggering 1,188 per cent increase in E. coli levels at the Serpentine Lido in Hyde Park, London, over the past year. This high-profile site recorded E. coli counts rising from 45 to 580. Equally concerning, intestinal enterococci—another type of bacteria often found in human faeces—soared by 1,085 per cent, from 27 to 320. These pathogens are not just numbers; they represent a serious threat to public health, prompting calls from experts for more rigorous monitoring of these waters.

The Bathing Mobility Advisory Service (BMAS) performed an analysis of water quality, revealing that the Serpentine Lido, which received a 'sufficient' rating from the Environment Agency, is symptomatic of broader challenges facing recreational water quality in the UK. The same analysis highlighted troubling figures from Hampstead Heath's mixed pond, where E. coli levels rose by 230 per cent from 100 to 310 between 2023 and 2024. These findings mirror a nationwide trend, as 33 per cent of designated swimming rivers and lakes are reported to contain harmful substances, including pharmaceuticals and pesticides, as identified by Watershed Investigations.

Public health experts stress the importance of effective testing and monitoring for pathogens, especially as the UK experiences an increase in recreational water use. Professor Davey Jones, a soil and environmental scientist at Bangor University, noted that while natural water bodies offer health and wellness benefits, they can also house dangerous pathogens. "Some pathogens, like E. coli 0157, can enter groundwater through agricultural runoff and pose serious health risks, even in small amounts," he stated, urging authorities to enhance their pathogen monitoring strategies.

The risk associated with swimming in these waters is not theoretical. A public health report from 2013 documented 338 cases of gastrointestinal symptoms among participants of the Hampton Court Swim, suggesting that swimming in natural waters, particularly in urban areas like the River Thames, can lead to health complications from undetected bacteria and viruses. Furthermore, recent reports of raw sewage spills entering designated bathing sites, notably in Belfast Lough, underline the deteriorating state of water governance. Northern Ireland Water admitted to breaching legal limits by discharging untreated sewage hundreds of times a year, posing another layer of threat to health and safety.

The situation is exacerbated by climatic factors; heavy rainfall can lead to increased bacterial contamination in water bodies due to existing weaknesses in the UK's water management systems. This expanding pollution presents immediate health risks, notably gastrointestinal illnesses, which the government has identified as growing concerns.

Nevertheless, the trend towards outdoor swimming continues. Proponents argue that the activity can enhance immune function, promote mental well-being, and even aid in weight loss. Some studies have shown that cold water exposure triggers physiological responses beneficial for health. However, this renewed enthusiasm for wild swimming must be tempered with caution. Despite the reported health benefits, it’s vital for swimmers to be aware of the surrounding environmental quality, as regulatory measures currently lag behind the rise in popularity of the sport.

The recent statistics and expert warnings, juxtaposed with the increasing trend of wild swimming, highlight an urgent need for a reevaluation of water quality monitoring practices in the UK. Still, as communities push for access to natural water bodies for recreation, ensuring safety must take precedence. The balance between enjoying nature and safeguarding public health will hinge on decisive and informed action from health authorities and regulatory bodies.

Ultimately, while the act of plunging into fresh waters can invigorate body and mind, it is essential to remain vigilant. Continuous efforts to reduce water pollution, enhance testing protocols, and raise public awareness about potential risks will be crucial to preserving the joy of swimming in the great outdoors.

Reference Map:

Paragraph 1 – ^[1], ^[4]
Paragraph 2 – ^[1], ^[2]
Paragraph 3 – ^[1], ^[3], ^[6]
Paragraph 4 – ^[5], ^[6], ^[7]
Paragraph 5 – ^[2], ^[4]

Source: Noah Wire Services

More on this

https://www.dailymail.co.uk/health/article-14742599/1000-rise-faeces-ecoli-UK-swimming-open-water-london.html?ns_mchannel=rss&ns_campaign=1490&ito=1490 - Please view link - unable to able to access data
https://www.itv.com/news/2024-12-13/pesticides-industrial-chemicals-and-ecoli-found-in-designated-bathing-waters - An investigation by Watershed Investigations found that 33% of UK rivers and lakes designated for swimming contained harmful substances, including pharmaceuticals, pesticides, and E. coli bacteria. Notably, Frensham Great Pond had the highest E. coli levels, while Hampstead Ponds in London had elevated PFAS chemicals. Although concentrations weren't immediately harmful, the long-term effects of these pollutants, especially in combination, remain uncertain. Swimmers have reported illnesses after using these waters, highlighting the need for improved water quality monitoring and pollution control measures.
https://www.bbc.co.uk/news/articles/cvgrewxxg1zo - A BBC Spotlight investigation revealed that raw sewage spills have led to E. coli levels exceeding legal limits in Belfast Lough, Northern Ireland. Northern Ireland Water admitted to breaching the law hundreds of times annually by releasing untreated sewage into the lough. The company cited decades of underfunding in its sewage network as the primary cause of these spills, raising concerns about the safety of recreational water activities in the area.
https://www.theguardian.com/environment/2024/nov/26/record-number-of-english-bathing-sites-classified-as-having-poor-water-quality - The Guardian reports that a record number of English bathing sites, 37 out of 450, were classified as having poor water quality in 2024. This includes 18 out of 27 new river sites designated for bathing, with many failing to meet minimum standards due to high levels of harmful bacteria like E. coli and intestinal enterococci. The findings underscore the challenges in improving water quality in rivers compared to coastal areas.
https://www.gov.uk/government/news/swimming-in-the-river-thames-can-carry-a-risk-of-gastrointestinal-illness - Public Health England's 2013 report highlighted the risk of gastrointestinal illnesses from swimming in the River Thames. An investigation into the Hampton Court Swim event found that 338 out of over 1,000 participants reported symptoms like nausea, diarrhea, and vomiting. The study suggested that ingestion of river water, possibly containing undetected viruses or bacteria, was a likely cause, emphasizing the need for caution when swimming in natural water bodies.
https://www.itv.com/news/2024-01-29/high-levels-of-bacteria-found-in-flood-water-samples-from-rivers-in-the-uk - ITV News reports that floodwater samples from UK rivers in Surrey, York, and Shrewsbury showed alarmingly high levels of E. coli and other bacteria, indicating fecal contamination. In Surrey, E. coli levels reached 1,080,000 cfu per 100ml, far exceeding the safe limit of 900 cfu/100ml. Such contamination poses significant health risks, including gastrointestinal illnesses, underscoring the dangers of exposure to floodwaters.
https://www.bbc.com/news/articles/cjm9yng34jyo - BBC News reports that testing at Steamer Quay in Totnes, Devon, revealed E. coli levels more than 20 times above minimum standards, classifying the water quality as poor. This site, designated as a bathing area, is scheduled to host the Dart 10K swim event. Organizers and local authorities are aware of the contamination and are planning improvements to address the pollution sources affecting the area.

Noah Fact Check Pro

The draft above was created using the information available at the time the story first emerged. We’ve since applied our fact-checking process to the final narrative, based on the criteria listed below. The results are intended to help you assess the credibility of the piece and highlight any areas that may warrant further investigation.

Freshness check

Score: 8

Notes: The narrative presents recent data on E. coli levels at London's Serpentine Lido and Hampstead Heath's mixed pond, indicating a significant rise over the past year. The earliest known publication date of similar content is from October 2020, when the Hampstead Heath Ladies' Pond was closed due to high E. coli levels. ([standard.co.uk](https://www.standard.co.uk/news/uk/hampstead-heath-ladies-pond-closed-e-coli-a4564566.html?utm_source=openai)) However, the current report includes updated figures and references to recent events, suggesting a higher freshness score. The narrative appears to be based on a press release, which typically warrants a high freshness score. No discrepancies in figures, dates, or quotes were identified. The narrative does not appear to be recycled content.

Quotes check

Score: 9

Notes: The narrative includes a direct quote from Professor Davey Jones, a soil and environmental scientist at Bangor University, regarding the risks of E. coli 0157 entering groundwater through agricultural runoff. A search for the earliest known usage of this quote did not yield any matches, suggesting it may be original or exclusive content. No variations in wording were found, and no earlier instances of this quote were identified.

Source reliability

Score: 6

Notes: The narrative originates from the Daily Mail, a UK-based tabloid newspaper. While it is a well-known publication, it has faced criticism for sensationalism and accuracy issues in the past. The reliance on a press release as the primary source may also raise concerns about the narrative's objectivity and depth. The report mentions the Bathing Mobility Advisory Service (BMAS) and Professor Davey Jones, both of whom are verifiable online, lending some credibility to the narrative.

Plausability check

Score: 7

Notes: The narrative presents plausible claims regarding the rise in E. coli levels at London's Serpentine Lido and Hampstead Heath's mixed pond, correlating with the increase in wild swimming activities. The Hampstead Heath Ladies' Pond has experienced similar issues in the past, with closures due to high E. coli levels reported in October 2020. ([standard.co.uk](https://www.standard.co.uk/news/uk/hampstead-heath-ladies-pond-closed-e-coli-a4564566.html?utm_source=openai)) The inclusion of expert opinions and references to recent events supports the plausibility of the claims. However, the reliance on a single source and the lack of corroboration from other reputable outlets may raise questions about the comprehensiveness of the reporting.

Overall assessment

Verdict (FAIL, OPEN, PASS): OPEN

Confidence (LOW, MEDIUM, HIGH): MEDIUM

Summary: The narrative presents recent data on the rise in E. coli levels at London's Serpentine Lido and Hampstead Heath's mixed pond, correlating with the increase in wild swimming activities. While the inclusion of expert opinions and references to recent events supports the plausibility of the claims, the reliance on a single source and the lack of corroboration from other reputable outlets raise questions about the comprehensiveness and objectivity of the reporting. The Daily Mail's history of sensationalism and accuracy issues further complicates the assessment. Therefore, the overall assessment is 'OPEN' with a 'MEDIUM' confidence level.

wild swimming
public health
water pollution
E. coli
UK environment