Amid rising concerns about climate change and public health, experts warn that the United Kingdom’s current system for monitoring bathing water safety may be inadequate to protect swimmers from a range of bacterial infections. This issue came to light following the case of eight-year-old Keeva McCarthy from Dorset, who fell ill after swimming at Avon Beach during this year’s August heatwave, despite the site holding the Environment Agency’s highest ‘excellent’ water-quality rating.

Keeva developed severe symptoms including high fever, diarrhoea with blood, and lethargy two days after swallowing seawater at Avon Beach. Hospitalized and treated for dehydration, she was diagnosed with campylobacteriosis, a bacterial infection typically contracted through contaminated food or water. Although her twin sister and other family members remained healthy, Keeva’s mother suspects the infection was linked to her swim, highlighting a potential gap in the safety testing regime.

Currently, bathing water quality in England is assessed based on levels of two bacteria: Escherichia coli (E. coli) and intestinal enterococci. These indicators stem from World Health Organization guidance issued in 2003 and subsequent European Union standards from 2006, intended to detect faecal contamination that might pose health risks. However, experts point out that these tests do not encompass a broader spectrum of pathogens frequently present in recreational waters, including campylobacter, salmonella, norovirus, and various parasites such as giardia and cryptosporidium.

Data from the environmental charity Surfers Against Sewage underline the potential scale of the problem. Between May and August this year, 57 percent of the 1,279 reported illnesses after swimming in natural waters occurred at locations officially rated as having ‘good’ or ‘excellent’ water quality. In August alone, 68 percent of 388 reported sicknesses followed visits to these high-rated sites, with reports including gastroenteritis, as well as skin, ear, and eye infections—some severe enough to require hospitalization.

A further emerging concern is the appearance of vibrio bacteria in UK coastal waters, typically associated with warmer, subtropical environments. Vibrio can cause serious wound infections and sepsis, with fatality rates estimated around 20 percent. Studies have detected increased vibrio levels in British estuaries during past heatwaves, such as the hot summer of 2018 when water temperatures significantly exceeded average levels. That year, northern Europe recorded an unusually high number of vibrio infections, raising alarms about the risks posed by warming seas.

Despite these risks, vibrio and other pathogens remain unmonitored in official UK bathing water assessments. Scientists and public health officials emphasize the need to broaden testing criteria to reflect changing environmental conditions and emerging threats. Anne Leonard, a senior environmental epidemiologist at the University of Exeter, highlighted that although official water quality ratings have improved over the past three decades, the actual likelihood of illness for bathers has not decreased significantly.

With sea temperatures around Britain reported several degrees above normal this summer, experts advocate for urgent updates to water quality monitoring protocols in both the UK and Europe. These changes would aim to detect a wider range of microbial hazards, thereby enhancing the protection of public health amid the ongoing challenges posed by climate change.