What no one tells you about the health risks of wild swimming

During the heatwave last summer, George Ames and his family and friends congratulated themselves on having found the perfect wild swimming spot. It was somewhere they had first visited during the pandemic, when wild swimming caught the national mood.

It was a calm, beautiful spot on the Medway in Kent, complete with a jetty. “It was just lovely,” says Ames, a 41-year-old PR executive. “We felt like we’d found this beautiful spot in the British countryside to enjoy.”

On this occasion, they were with three other families who had travelled for the day from their neighbourhood in south-east London. “There were lots of local teenagers jumping in and paddleboarders passing through. The kids were absolutely delighted. In the car on the way back, my daughter said, ‘Mummy and Daddy, I’ve had such a brilliant day today.’ It was this great moment.”

Events unravelled quite quickly soon after. The next day, messages started to appear in their WhatsApp group, asking: “How is everybody doing?” One by one, they each started reporting sickness. “My daughter Ivy, who was 10, and I were sitting in the living room with a fan trained on us. It was during the extreme weather and we had high fevers and felt like death.”

An ambulance had to be called for one of their group, who ended up in hospital on a drip for two days. While samples taken from her were lost as a result of the hospital’s fridges failing during the heatwave, doctors were confident in diagnosing the cause: e-coli. The only person out of the group of 11 not to become ill was George Ames’s wife, Vicky, who had kept her head above water.

Wild swimming, or what used to be called simply swimming, has surged in popularity in recent years. In 2020, membership of the Outdoor Swimming Society rose by 75,000, and its website received one million unique users in 2021.

The health benefits of outdoor swimming, both physical and mental, have been exalted, while the risks due to poor water quality have been largely washed over. In 2020, the UK ranked last in Europe for bathing-water quality. In January this year, it was revealed that Southern Water had been pumping sewage into Chichester Harbour, an Area of Outstanding Natural Beauty, for 19 days straight. Last Sunday, an oil leak from a pipeline in Poole Harbour, Dorset, put the spotlight back on the issue of water pollution. Since the leak, the public has been urged to avoid using the water and beaches within Poole Harbour. But, meanwhile, elsewhere in the country, wild swimmers take risks every day, calculated or not, when they take a dip.

Just 14 per cent of English rivers are of good ecological standing, according to the Environment Agency, and all our rivers fail standards for chemical pollution.

The UK has more than 600 designated Bathing Waters – sites that are popular for swimming and paddling and have been identified under the Bathing Water Regulations 2013. Live water-quality monitoring exists only at these sites, most of which are coastal, with only 16 lakes and parts of two rivers: the Thames at Port Meadow, in Oxford, and on the River Wharfe at Ilkley, West Yorkshire. Which means that only a few hundred yards of the thousands of miles of the UK’s river waters are monitored for human health and safety.

Last year, the site in Ilkley, which attracts hundreds of swimmers during periods of warm weather, failed to reach quality standards after samples of water from there were tested by the Environment Agency. Much of the national problem stems from the fact that the UK sewage system is unable to cope with both sewage and high volumes of water during heavy rain. Storm overflows are not operated manually, they simply release excess storm water when the sewer levels naturally reach a critical level.

According to data from the Environment Agency, UK water firms discharged raw sewage more than 770,000 times over the course of 2020 and 2021. Data for May to September 2022 show that sewage was released 5,504 times across more than 15,000 hours.

“No one is going to be able to guarantee a safe swimming experience in inland waters as long as we have poor-quality sewers,” says Prof Harvey Woods, founder of the Clean Rivers Trust.

The term “wild swimming” might seem like hyperbole to describe your annual summer dip in the sea, but – given the pollution that we know is released – it’s ironically more accurate than you’d think.

The charity Surfers Against Sewage (SAS) received 720 sickness reports over the past year, submitted via its Safer Seas & Rivers Service app (the app is designed to allow people to make informed decisions about when and where they use the water, using real-time data to alert you to sewage pollution incidents). That was an increase compared with the previous year, when 286 people reported falling ill after entering the water, and the same time period in 2019-20, when there were 124 sickness reports.

Gastroenteritis was the most common illness reported to the charity by wild swimmers after entering the water. Ear, nose and throat infections were common, too, with respiratory, skin and urinary-tract infections also reported, it said.

“It’s wrong that in 2023 we still need this, but regular discharges of raw sewage into our waters make it a necessity for the public to have access to the information they need to decide whether it’s safe for them to enter the water,” says Izzy Ross, of Surfers Against Sewage.

Ross and SAS are continuing to improve the SSRS app and are working with communities to get more designated bathing-water sites. Their aim is to improve testing and monitoring to hold polluters to account.

But the issues go beyond sewage. Contamination from agricultural land and private septic tanks is an issue, as is run-off from duck and geese faeces. Weil’s disease is contracted from the urine of infected rats; it killed the Olympic rowing champion Andy Holmes in 2010.

In the case of George Ames and his group of swimmers in the Medway, the cause was untreated sewage, which Ames subsequently discovered can be legally emptied into the Medway from boats’ waste tanks. Looking at a detailed map, he also found out that upstream from where they swam was a sewage outlet.

When he contacted Medway Council to ask them to test the water and inform other bathers of the poor quality, it quickly became an awkward situation: “They said it was not a designated swimming area, but to me it was clearly a place with an infrastructure for water activities.”

The council eventually stencilled a sign onto the jetty deck that says “No swimming”. ­­Not that Ames or any of his group would ever swim in a British river again.

“Wild swimming is lovely,” Ames says. “That sense of adventure is amazing, be it in rivers or oceans, but I think it is incompatible with the realities of how incredibly polluted and unsafe our waterways are. It’s a level of pollution you might expect from developing countries with real challenges, not the UK in 2023.”

However, Kate Rew, author of The Outdoor Swimmers’ Handbook and founder of the Outdoor Swimming Society, believes the dangers are being overstated. “In terms of the number of swims people are doing and the number of incidences of sickness, the risk doesn’t feel overwhelming to the wild swimming community.”

A survey of Outdoor Swimming Society members in 2022 found that of 1.85 million swims logged all around the world, only 207 incidents of sickness were attributed to water quality.

“That’s one incidence of sickness for every 9,094 swims,” says Rew. “We all want clean water. But I’d be upset to see people put off swimming because they think the risk is too big to get in. You have to weigh the risks up. We know whenever we get into a car, we could have an accident.”

After 30 years of wild swimming, Daniel Start, who has written numerous books on the subject, has never been ill. “Our waters are cleaner than at any time in living memory, but that’s not saying much, given the scale of industrial pollution that once existed.”

He always swims breaststroke and keeps his mouth firmly shut, especially when leaping in. “Kids, especially, need to be reminded about this,” says Start. “I also choose locations away from towns and settlements as much as possible. Water is very good at self-cleaning as it flows – it mixes with oxygen and is blasted by sunshine – but in an ideal world, untreated sewage would never be released into our waters.”

Some water companies are getting better at alerting the public when they are releasing sewage. Thames Water now has an interactive digital map that reveals storm discharge. It comes a little too late for ecologist Debbie Campbell, who had thought she was good at assessing the risks. During the first lockdown in 2020, she was left vomiting and suffering from diarrhoea after she jumped into the River Windrush near her home in Cirencester in the Cotswolds. She now works on the Windrush Recovery Project.

While Thames Water’s map is a step in the right direction, she says, it’s come too late for her. “It’s really good that they’ve released data, which they didn’t before,” says Campbell. “If it had existed back in 2020, then I would have known that they’d pumped sewage into the river four days earlier. Now it’s become a popular thing that people are wild swimming, we need things like this for health safety.”

However, she has not swum in a river since. “I’ve actually built a very big pond in my garden for swimming,” she says.

“And I know what’s in it. My two kids used to love splashing about in the river, but I won’t let them anywhere near it now.”