Water companies have been engaging in so-called dry spills, releasing sewage on to beaches and into rivers even when it is not raining, according to a prominent campaign group.
In its latest report on the water industry, Surfers Against Sewage (SAS) discovered that 146 dry spills were detected over a 12-month period.
Sewage spills are only supposed to happen under exceptional circumstances; when it is raining so heavily the system cannot cope with the amount of water and effluent being spewed at once.
SAS analysed meteorological data from the Met Office alongside spillage data to record its findings.
As part of its water quality report, SAS also analysed data from 720 sickness reports submitted to its reporting system.
Its data found that over a third (39 per cent) of sickness cases correlated to sewage discharge alerts, while 63 per cent of cases that were reported to a doctor were attributed to poor water quality.
The most common illness reported after people swam in the sea or rivers was gastroenteritis, with two in three people reporting symptoms associated with the condition.
Ear, nose and throat infections were also common, with respiratory, skin and urinary tract infections also reported.
Amy Slack, head of campaigns and policy at SAS, said: “Over the last year, the UK public has made clear their disgust at what’s happening to our rivers and seas, and yet water companies continue to pollute at will.
“It’s high time the government stepped up and took real action to curb the destructive and selfish behaviour of the water companies responsible for this literal shit storm.”
SAS is calling for a 90 per cent reduction in untreated sewage discharges by the end of the decade.
The water industry has faced sustained criticism for its treatment of sewage.
Ofwat, the sector’s watchdog, has slapped six water companies with enforcement cases.
It also teamed up with the Environmental Agency to announce investigations into all water and wastewater companies last November.
Southern Water has been approached for comment.