Its 2022 Water Quality Report uncovers “potential illegal” sewage discharges alongside more than 700 cases of illness that are attributed to the releases.

The report used rainfall data to investigate potentially illegal “dry spills” – sewage outflows are typically only permitted in unusually heavy rainfall when infrastructure is unable to cope.

Southern Water was responsible for four times as many dry spills as the next worst offender, South West Water, SAS said.

The analysis also shows that some water companies offloaded untreated sewage into waterways even when there hasn’t been any rain. This summer, SAS claimed that there were 5,504 incidences of raw sewage being dumped into bathing waters over a period collectively lasting for longer than 15,000 hours.

The untreated sewage contaminated beaches and riverbanks which water enthusiasts, holidaymakers and families used for recreational activities throughout the summer.

The report also found 103 times...