Wild swimming is becoming an in the UK – especially in the summer when temperatures soar. With the recent news that have been designated bathing waters in England, many more may be thinking of giving this hobby a try.
Author
Georgios Efthimiou
Lecturer in Microbiology, University of Hull
But with Environment Agency reports revealing nearly were discharged into England’s rivers and coastal waters last year – nearly double the number of spills reported in 2022 – many may be wondering if it’s still safe to swim, even in these designated spots.
Raw sewage can contain a variety of germs that can seriously harm our health.
Some examples are (which most of us know better as E coli), which can cause both gastrointestinal and urinary infections. Some of the it can cause include severe diarrhoea, stomach cramps, vomiting and pain during urination. It can also .
This type of bacteria is one of the waterborne pathogens in English waterways, and has in .
Infections with Salmonella enterica, Shigella flexneri, Vibrio cholerae and Campylobacter jejuni – all of which can also be – can cause similar symptoms as E coli.
(leptospirosis) is another bacterial infection that can be picked up from sewers, rivers, ponds and canals that are . Most people who catch Weil’s disease will have no symptoms – or will only experience mild flu-like symptoms. But some people get seriously ill, developing a fever, body pain, nausea, diarrhoea and jaundice (yellowing of the eyes and skin). can also get ill from leptospirosis by drinking or bathing in contaminated waters.
Several viruses can also be spread through wastewater. , for instance, both cause diarrhoea and vomiting. These can also be spread in swimming pools.
Hepatitis A can be spread in wastewater as well. This can lead to if not treated promptly. Fortunately, the chances of catching hep A from a wild swim are quite low – unless you .
Many of the microbes in sewage water might be , as they might have been exposed to these drugs before. antibiotics used to treat both humans or animals. This means that infections caused by these bacteria may be more .
Sewage also often contains high levels of , such as cadmium, lead and mercury. These can lead to or even in rare cases if ingested in high levels.
can also be in river waters, especially when farmlands become flooded. Symptoms linked to range from immediate short-term effects (headaches, dizziness, muscle twitching, weakness, tingling sensations, nausea) to more after long exposure (more than 24 hours) or at high levels of exposure – including birth defects, learning disabilities, behavioural changes, organ damage, cancer, brain tumours and asthma.
Safe swimming
When someone is swimming, contaminated water can enter the body through the ears, eyes, nose, mouth and urinary tract. Infections can also sometimes enter through the skin if someone has a wound, cut or abscess.
The dose of the infectious agent (the number of bacterial cells or viral particles) is also an in whether a person gets sick from wild swimming or not. The dose depends both on the “microbial load” of the wastewater (microbial cells per millilitre) and the amount of water swallowed by the swimmer.
For example, Salmonella needs about a to cause disease – but Streptococcus only need .
Different microbial strains have different infectious capacity, so it’s not always easy to predict the severity of a waterborne illness. Some strains of E coli, for instance, are more virulent than others with only needed to cause infection.
Although wild swimming may come with risks, there are many things you can do to protect yourself and avoid illness.
First, only swim in areas that have been officially designated as . These will be by the Department for Environment, Food and Rural Affairs throughout the bathing water season (between May and September) to monitor levels of both microbial and chemical contaminants and ensure waters are of suitable quality for swimming.
There are several online tools you can check to know whether a specific location is suitable for swimming – such as and the .
When wild swimming, protect yourself by wearing earplugs and goggles. This will help prevent you from getting ear and eye infections if exposed to contaminated waters. Avoid swallowing water when you swim. By staying informed and taking necessary precautions, you can still enjoy a refreshing wild swim.
Georgios Efthimiou does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
