Wild swimmer
Photograph: Shutterstock / Time Out

Is it time we stopped going wild swimming?

We’ve all experienced the high of plunging into a chilly body of water. But scientists say we shouldn’t overlook the risks

Amy Houghton

Can you imagine anything better than breast-stroking through murky brown waters at teeth-chattering temperatures? Jo Robb can’t. She dives into the Thames several times a week with wild-swimming group the Henley Mermaids (self-described ‘maniacs’), and is effusive about the benefits: ‘It fosters this connection with nature and with the river.’ Joan Fennelly, a fellow Mermaid, agrees: ‘You can go down to the river in a foul mood and you will always come back with a smile on your face… most of the time.’ 

Wild swimming took on cultish momentum during and after the lockdowns of the pandemic. Since 2020, the Outdoor Swimming Society’s membership has risen by 75,000 and its website received one milllion unique users in 2021. But an explosion in popularity also meant a rise in the number of people facing the grimmer aspects of outdoor bathing (and there’s a lot of them). Most recently, doctors have issued warnings of ‘swimming-induced pulmonary oedema’ – a condition that causes the lungs to fill with fluid, causing even healthy swimmers to potentially ‘drown from the inside’. 

Advocates insist that the hobby induces a ‘high’ and there have been studies to suggest that it could indeed cause a release of beta-endorphins, dopamine and serotonin – all good things. Victoria Halstead and her husband have been swimming around the Lake District since the summer and have persisted through the cold winter months. ‘The mental impact of it is second to none,’ she says. ‘I’ve not done any other activity that’s had that same effect.’  

Wild swimmers in Wales
Photograph: Shutterstock

But as millions more of us have got into wild swimming, scientists have become increasingly worried. Mike Tipton, professor of human and applied physiology at the University of Portsmouth, says: ‘Programmes like Wim Hof’s BBC show [‘Freeze the Fear’] made it seem like all you need to do to cure everything is to leap into cold water... not only was I concerned, but the coastguard was concerned.’ 

Between 2018 and 2021 there was a 79 percent increase in open-water swimming deaths across the UK. In 2021, the coastguard reported a 52 percent rise in callouts related to wild swimming. Of all the risks associated with the hobby, cold shock response is the most common. In chilly temperatures, the heart has to start working harder to pump the same volume of blood around the body, risking hyperventilation and hypothermia. You don’t need us to tell you that that isn’t good news at all.

Between 2018 and 2021, there was a 78 percent increase in open-water swimming deaths across the UK

In September Professor Tipton published a report in response to the string of warnings issued by the authorities over the summer as hypothermia rose. It emphasised that there is currently far more scientific evidence of the dangers of wild swimming than of its supposed benefits, which just might be what you suspected all along. While he doesn’t dismiss cold-water swimming altogether, he does urge people to practise certain safety measures including entering the water gradually, spending less time in colder temperatures and investing in a tow float, so you can be seen more easily. ‘We’re not the fun police,’ he says. ‘We’re just saying that if you do it this way, you will maximise the chance of getting the benefits and minimise the risks.’

Halstead says her husband suffered a panic attack the first time that he hit the water and on a later occasion had cold shock. But these bad experiences didn’t deter either of them – it was ‘the first time his head was clear in years’. They now take almost all the safety precautions recommended by Professor Tipton and others. 

Sewage discharge
Sewage discharge on a British beach. Photograph: Shutterstock

But what’s worrying a lot of people now is contamination. There’s more toxic bacteria (including e.coli and intestinal enterococci) in our waters than ever, with more than 20 times the maximum levels allowed in many inland bathing areas. Campaigners say that most of this pollution comes from water companies illegally discharging raw sewage off our coasts and into our waterways. According to Labour Party analysis of figures from the Environment Agency, there’s been a whopping 2,553 percent (yes, you read that right) increase in the number of hours that water companies have spent dumping raw sewage. 

One person who’s had a really rough time of it is Adrian Malhew. He hasn’t been swimming in fresh water since 2019 after getting repeatedly ill and eventually being admitted to hospital for three days. ‘I was vomiting quite a lot, losing a lot of fluids and started to bleed from orifices you really don’t want to be,’ he says. He had contracted leptospirosis – a bacterial infection spread through animal urine. Malhew had the disease once before in the 1990s, but noticed that water quality had deteriorated even further over the next two decades. Over and over again, he became ill in waters he had been confident enough to swim in for 20 years.

More than half of bugs were caught in areas where water quality was classified as ‘excellent’

A survey by Surfers Against Sewage (SAS) in May found that more than half of those who had swum in open water later became ill. The organisation runs a service where bathers across England and Wales can report when they have experienced sickness caused by wild swimming – something that could lead to repercussions for sewage firms (allegedly) dumping sewage illegally. By far the most common condition was gastroenteritis, an infection that causes bouts of vomiting and diarrhoea. Alarmingly, more than half of cases were in areas where the water quality has been classified as ‘excellent’ by the government. 

SAS explains that regulators only take samples in the summer, which doesn’t account for the hardy types who keep going through winter. Samples are also only taken from designated spots, not necessarily anywhere near the most polluted areas. This means that information around water contamination can be pretty misleading, to say the least.

Wild swimmer
Photograph: Shutterstock

Henley Mermaids have (somewhat accidentally) become campaigners against the influx of sewage into British waters after almost every member of the club got sick. Robb found herself experiencing flu-like symptoms following one excursion in the Thames. Days later, she figured out it was gastroenteritis. ‘Knowing what I know now from our campaigning work I know that the stretch of river where I got sick was a stretch of river where there is a great deal of faecal bacteria,’ she says. Robb now relies on an interactive map from Thames Water to determine where it is safe to bathe. ‘When I check that map every day I’m still shocked by how the treatments are discharging almost constantly,’ she adds. ‘Right now it’s just a sea of red and orange.’

She is keen to add that this should not mark the death of outdoor swimming. ‘The worst thing that could happen is that this puts people off something that we should have a right to be able to do,’ she says. ‘These are our rivers, not open sewers for private water monopolies. We should all be in rivers, year round, enjoying the benefits of nature.’ 

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