Discharges of raw sewage into rivers near Oxford have tripled since 2018, a report by a campaigning group has claimed.

The Oxford Rivers Improvement Campaign (Oric) analysed data on spills from sewage treatment works into rivers, and found that untreated sewage was discharged on average 58 times by each plant, compared to 19 times in 2018, according to The Independent.

Sewage was discharged for an average of 821 hours in 2020 by the sewage plants being monitored, the report claimed. That compares with 193 hours in 2018.

Oric, a pressure group of Oxford residents, analysed data from the Environment Agency, Thames Water and the National Rivers Trust.

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Oric’s report says: “It is quite clear from our analysis that far from being a last resort, untreated sewage is being released into the Thames and its tributaries, every week if not every day, on an entirely routine basis.

“In theory, a permit is required before such discharges are allowed. The sheer scale of spillages which are occurring indicates that either permits are being granted on an entirely casual basis or else many of the discharges are illegal, but little or no enforcement action follows.

“Either way, the current regulatory system is not working. Prosecution remains relatively rare. We suspect this is partly due to a lack of resources at the EA.

“Thames Water’s wastewater infrastructure has been chronically underfunded for many years, resulting in the capacity of STWs [sewage treatment works] being inadequate for the populations they serve; a problem which will only be exacerbated by climate change and future housing development.”

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A Thames Water spokesperson said: “We’ve received the report and will be looking at it carefully in the coming days.

“We regard all discharges of untreated sewage as unacceptable and will work with the government, Ofwat and the Environment Agency to accelerate work to stop them being necessary.

“We have an unprecedented amount of investment directed towards safeguarding our rivers and streams. Between 2020 and 2025 we are spending £1.25bn on maintaining and improving our operational sites, including contributing to the health of 745 km of rivers across London and the Thames Valley.”

An Environment Agency spokesperson said: “Storm overflows must only be used under strict permitted conditions that control their environmental impact.

“There has been no relaxation of storm overflow permits, which set out the specific sewage flow rates that storm overflows must meet before any discharge to the environment can take place. It is an offence if an overflow occurs and this flow rate is not met.

Last year Sir Bob Geldof backed a campaign to refuse payments to Southern Water after the company was fined £90m for discharging sewage into the sea.

Geldof was speaking at climate change event at Faversham Assembly Rooms and said, according to Kent Online, “Don’t pay your water bills to Southern Water – they can f*** off. God bless the people of Whitstable. I’m straight there to join them. In fact, I’ll join them immediately.”

“I can’t understand why this giant utility company can’t be held to account. I really don’t understand it.”

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The non-payment campaign was started by four residents of Whitstable in Kent.

The campaign came after the company was handed a record fine of £90m after pleading guilty to illegal discharges of sewage which polluted rivers and coastal waters in southern England, the government said.

The Environment Agency said the case, the largest in its history, saw pollution offences from 16 waste water treatment works and one storm overflow and that Southern Water pleaded guilty on 51 counts.

"With nature in crisis, no one should profit from undermining environmental laws," Emma Howard Boyd, chair of the Environment Agency, said in a statement this summer.

"This sentence shows fines for environmental offences are starting to reach the same level as the highest fines for crimes in financial services and that is good."

Local Conservative councillor Ashley Clark wrote to Southern Water: “I have no intention of contributing to the £90m fine recently imposed on that company for criminal activity.

“Throughout the summer Southern Water has continued to send my untreated sewerage, along with that of other local people, directly into the sea, which I use on a daily basis to swim from April to October.

“I find the thought of swimming in a mixture of local sewerage and seawater totally abhorrent and not something that I should be charged for. If I paid someone to clear out my garage and take rubbish away to the tip but instead they fly-tipped it into the countryside, I would be upset. Canterbury City Council prosecutes offenders for that type of activity.

“Yet Southern Water continues to fly-tip sewage into my bathing water with impunity.”

Watch: Sewage spills into UK rivers soar 88%