When water pollution is rife in the UK, where's safe for wild swimming?

The popularity of wild swimming in UK rivers has boomed in recent years — especially since the pandemic, when people sought a closer connection with nature. But as our interest has taken off, so too have headlines about poor water quality from sewage and chemical pollution. So what exactly is happening, and how safe is it to take a cooling dip this summer?

What’s happening in UK rivers?

Sewage spills and agricultural pollution are the leading causes of dirty rivers. And the latest figures are alarming: only 14% of England’s rivers are classified as being of ‘good’ ecological status, according to a government report published in January 2022. That year, 375,000 sewage spills into rivers and other waterways in England and Wales were recorded.

Why is it a difficult issue? 

Community groups have been galvanised to form local campaigns to tackle river pollution, while both The Times and The i newspapers have launched drives to raise awareness and attempt to force a change in government policy. However, environmental experts point out that there’s a lack of quantitative knowledge. 

“It certainly isn’t a trivial amount,” says Professor Andrew Singer, a senior pollution scientist at the UK Centre for Ecology & Hydrology, on the number of sewage spills. “But we don’t know the volume of sewage coming out through pipes, so we simply don’t know to what extent our waters are polluted. The safest thing to say is no river hits the standard level for bathing water. But there are places that are sufficiently clean.”

Leading the river water quality group at the same centre, Dr Mike Bowes adds: “The Environment Agency tests waterways regularly, including rivers, but in the past three to four years, this has fallen from monthly testing to quarterly testing, so the data is a bit sparse.” He also heads the River Thames Initiative, which monitors the water on a weekly basis. “The presence of phosphates — a sign of sewage and fertiliser from agriculture reaching waterways — has fallen 90% since the late 1990s, and that’s clearly due to improvements in the disposal of sewage,” he says. He points to legislation like the 1991 Urban Waste Water Treatment Directive, which has overhauled UK rivers in recent decades. “Rivers are definitely cleaner than they were 30 years ago.”

How can I tell if a river is clean enough to swim in?

To help you make a decision, download the Safer Seas & Rivers Service app, which has been created by the charity Surfers Against Sewage. It alerts water users when untreated sewage is discharged into waterways and logs the water quality in real time at 370 locations across the country. You can also consult the Rivers Trust sewage map, which shows how many spills happened at monitored locations in England and Wales in the previous year and offers the best indication of whether you’re in an area exposed to raw sewage overspills. 

It’s also best to avoid rivers a day after heavy rain. Simon Griffiths of Outdoor Swimmer magazine says: “Water quality tends to get worse around heavy rain, since agricultural waste and other pollutants can run off into the surrounding waterways. In addition, heavy rainfall can cause sewer overflows to discharge.” 

It may sound obvious, but a sight and smell test can help, too. Kate Rew, author of The Outdoor Swimmers’ Handbook, says: “Check for odours, floating pollutants and blue-green algae on the surface — your instincts serve you well, so go elsewhere or wait a day if it just doesn’t feel right.”

What else should I know?

If you do dive in, there are precautions you can take. Daniel Start, author of Wild Swimming Hidden Beaches, says: “Don’t swallow the water when swimming — keep your mouth closed and spit out anything that gets in it. Avoiding front crawl can also help — stick to breaststroke.”

It can also be worth going with a dedicated swimming group, which will do all of the hard work of selecting an appropriate spot. Above Below runs regular retreats across the UK using RuckRafts — waterproof inflatable rucksacks that can be filled with belongings and towed. 

Bear all of this in mind and you can find plenty of safe swimming spots across the country — from the slow-moving waters of the Deben in Suffolk to the stunning canyons of the Etive in the Scottish Highlands.