Real-time pollution warnings are needed at Lake Windermere after two people swimming there were taken to hospital last summer, campaigners have said.
A seven-year-old boy developed life-threatening kidney failure following an E coli infection allegedly linked to him swimming in the lake.
Windermere, in the Lake District in Cumbria, is one of the UK’s most popular open-water swimming destinations and attracts millions of visitors every year.
In August last year, Claire and her family were kayaking in the lake when she noticed the water appeared murky, but she said she was reassured by the Environment Agency’s “excellent” bathing water classification.
But hours later, her seven-year-old son became violently ill, suffering severe vomiting and rectal bleeding.
He was admitted to hospital but his condition rapidly deteriorated, and after three days, he was transferred to a regional children’s hospital.
The boy was diagnosed with haemolytic uraemic syndrome (HUS), a life-threatening condition which is one of the leading causes of sudden kidney failure in children.
Four days later, he experienced hallucinations after toxins from the infection began affecting his brain.
Tests confirmed he had contracted E coli 0157. Doctors established the infection was caused by exposure to contaminated water. It was the same strain responsible for the death of Heather Preen, whose case was explored in the Channel 4 docudrama Dirty Business.
The boy had two emergency operations, required dialysis to keep his kidneys functioning, received several blood transfusions and suffered serious complications, including a collapsed lung, during the six weeks he spent in hospital.
In June 2025, 42-year-old Graham went paddleboarding with his children on the lake and spent around 30 minutes in the water.
Days later he developed a urinary tract infection, which escalated into life-threatening sepsis when antibiotics failed.
Hospital tests confirmed he had been infected with ESBL-producing E coli, a strain which is resistant to many common antibiotics and is typically associated with faecal contamination.
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He was discharged after 10 days on intravenous antibiotics, but deteriorated again, suffering septic shock and requiring seven more days in hospital.
His consultant concluded the most likely source of infection was exposure while swimming in Windermere.
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Matt Staniek, founder of campaign group Save Windermere, said: “We are told Windermere’s water quality is ‘excellent’, but that label is dangerously misleading.
“People are ending up in hospital. Sewage is being dumped into the lake, yet the government continues to allow England’s largest lake to be polluted by the water company without real-time public warnings.”
Mr Staniek added: “The EA already operates real-time forecasting elsewhere; it must now bring it to Windermere. The government must end sewage pollution in Windermere and put people before profit.”
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The group has called for the immediate introduction of pollution risk forecasting at Windermere as well as clear public signage and an accessible online portal providing real-time pollution information.
It comes after a comprehensive analysis of water quality in 2025 found bathing water quality across much of the lake is poor during the summer months, with elevated levels of bacteria indicating sewage pollution peaking when recreational use of the lake is at its highest.
