Water companies spilled raw sewage into coastal bathing waters used by holidaymakers and families 5,517 times in the last year, an increase of more than 87%, new data reveals.

The discharges, through storm overflows, went on to beaches that were supposed to be the cleanest and safest in England and Wales, used by children, tourists, surfers and swimmers.

“We are in the midst of a new wave of sewage pollution,” said the 2021 Water Quality report by Surfers Against Sewage. “There are hundreds of thousands of sewage discharges polluting rivers and coastlines, all of which could impact the overall health of aquatic ecosystems.”

The data is gathered from water company alerts of spills via storm overflows across 308 locations. During the bathing water season – 15 May to the end of September – water companies issued alerts 3,328 times. The rest of the spills took place outside those months.

Storm overflows are supposed to be used in emergencies to ease pressure on the system after extreme weather or exceptional rainfall. But this report adds to the growing evidence that they are being used routinely.

Southern Water, which was fined a record GBP90m this year for billions of litres of raw sewage spills, issued 1,194 alerts of sewage spills, an average of 38 spills for each bathing water location, compared with an average of between two and eight for other water companies. Almost 30% of the 286 health reports submitted this year came from Southern Water’s operating area.

South West Water also produced a “notably poor performance for the third consecutive year”, with 406 discharges in the bathing water season on to popular beaches.

Hugo Tagholm, the chief executive of Surfers Against Sewage, said: “The findings of our report are shocking and outrageous, but they are by no means unexpected. Time and time again, governments have claimed concern over the pollution of rivers and seas, but have so far failed to take concrete action to change the status quo. Loopholes in laws and systematically defunded regulators have left water companies to run amok.”

For the first time the campaign group carried out testing of water quality at river mouths feeding into bathing beaches. The results were “shocking.” In six out of eight rivers the quality of the water was so poor as a result of faecal contamination that it posed an extreme danger to human health.

The findings come as the Environment Agency continues a major investigation into more than 2000 sewage treatment works after water companies admitted they may be illegally discharging raw sewage. Concerns over sewage dumping into rivers and seas have sparked grassroots campaigns all over the country. Members of the public in Southern Water areas have taken to beaches to protest and some have begun a rate payers revolt.

The citizen testing at river mouths provided a strong comparison to water quality testing undertaken by environmental regulators, and was carried out to fill the gap in the monitoring of river water quality. Only one river in the UK – the Wharfe in Ilkley – is a designated bathing water and therefore subject to the same scrutiny as coastal waters. The rest are not monitored for faecal pollution, despite the fact that 90 percent of storm overflows discharge directly into rivers.

Only 14 percent of rivers in the UK are of good ecological standard, a rating that suggests they are as close to their natural state as possible.

The rivers tested were; Afon Wyre River flowing into Llanrhystud Beach, Hoffnant River, flowing into Penbryn Beach, Figgate Burn into Portobello Beach in Scotland, River Bann flowing into Portstewart Beach in Northern Ireland, Seaton Burn flowing into Seaton Sluice Beach, Northumbria, the River Adur into Southwick Beach in Southern England, the River Ribble into St Agnes Beach in northwest England and the Cadoxton River flowing into Whitmore Bay Beach, Barry Island, south Wales.

E.coli levels in Figgate Burn were continuously at a level that poses an extreme risk to public health.

At the remaining five river locations results consistently showed faecal contamination levels that posed an extreme risk to public health.

Water quality at the River Bann and Cadoxton river was excellent.

Dr Christian Dunn, senior lecturer in natural sciences at Bangor University, said: “Untreated sewage can be a death potion to our rivers and waterways. It is a cocktail of harmful viruses, bacteria and chemicals. Some of these can directly harm aquatic life and others lead to devastating disruptions in the oxygen levels of the water – risking entire ecosystems … Rivers are essential for the health of entire landscapes, our wildlife depends on them, and there’s no surer way to destroy a river than flooding it with sewage.”

A spokesperson for Water UK, an industry body, said the companies recognised the urgent need for action to protect and enhance the UK’s rivers and seas.

“Our recent 21st Century Rivers report sets out the key steps needed to achieve the radical changes we all want to see, including calling on government to bring forward legislation in a new Rivers Act that will provide greater protection for rivers in law. We know we need to go further and water companies want to invest more to improve infrastructure and stop harm from storm overflows and outfalls.

“With our coastal bathing waters we have a good base to build on with more than 70% rated as ‘excellent’, and over 90% as either ‘excellent’ or ‘good’. This improvement has come about thanks to collaborative working between industry, government, regulators and other stakeholders over several years.”

Dr Toby Willison, director of environment and corporate affairs at Southern Water, said: “We share the passion and commitment of Surfers Against Sewage to protect our precious coastal water and the 700 miles of coastline in our region.

“We know our performance has to improve and we are driving a step change in investment spending GBP2 billion to cut pollution incidents by 80 per cent by 2025.

“Our new task force aims to cut storm overflows by 80 per cent by 2030. Our target is ambitious but all 83 of our bathing waters meet strict European standards and 78 are excellent or good, a challenge which 20 years ago seemed impossible.”