Sewage regularly dumped illegally in England and Wales rivers

Untreated sewage is being dumped illegally in rivers across the country on a regular basis, analysis shown to the BBC suggests.

It found seven water companies in England and Wales discharged untreated sewage into rivers and the sea more than 3,000 times between 2017 and 2021.

The water industry admitted action was needed to address the problem.

The fresh data comes a week after MPs warned of a "chemical cocktail" of pollutants tainting England's rivers.

The Environmental Audit Committee said raw sewage and microplastics were putting health and nature at risk.

Chairman Philip Dunne MP said self-monitoring by water companies had "allowed a blind eye to be turned" to unpermitted sewage discharges, which he said were unacceptably high.

He urged regulators and water companies to "get a grip" on the situation.

If illegal discharges were to continue, Mr Dunne said water regulator Ofwat should look at its powers to review those water bosses who receive "lofty bonuses".

Peter Hammond, a retired professor of computational biology and also a campaigner with Windrush Against Sewage Pollution, said the statistics showed that the water industry was flouting poor regulation by the Environment Agency.

"In some cases, multiple sewage works are spilling into the same river causing damage for long periods of time, sometimes spilling as long as four months, six months almost without a break," he said.

He calculated that together the seven companies - Southern Water, South West Water, Thames Water, United Utilities, Wessex Water, Yorkshire Water and Welsh Water - discharged untreated sewage from 59 treatment works that treat 4.5 million people's wastewater.

Water companies are allowed to discharge untreated sewage into rivers in exceptional circumstances - for example during heavy rainfall.

They can be acting illegally if they discharge when the conditions are dry - this is known as a dry spill. Or they can be breaking the law if they are not treating enough of the sewage before they discharge it - this is known as an early spill.

Prof Hammond looked at data from "event duration monitors", which check every 15 minutes on whether a treatment works is discharging untreated sewage into a river. He then compares this data with rainfall data and with the companies' records on how much sewage they're treating.

In response to the report United Utilities, Southern Water and Welsh Water, questioned the accuracy of some of the data while Yorkshire Water said that Prof Hammond had "fundamentally misunderstood" the data.

According to the report the sewage treatment works at Dorking run by Thames Water was responsible for the highest number of unpermitted spills.

Untreated sewage was discharged into the River Mole on 223 days over the last four years. Prof Hammond's analysis suggests none of them would have been permitted by the rules, because either the weather was too dry, or not enough of the sewage had been treated properly.

Thames Water said it ''regards 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 and say they are determined to be transparent".

Prof Hammond said the Environment Agency is failing to detect thousands of illegal spills because it is not scrutinising the available data closely enough.

''It's as if the Environment Agency is looking through a telescope and we're looking through a microscope."

Water UK, which represents the water companies, said all the water companies agree there is an ''urgent need for action to tackle the harm caused to the environment by overflows".

An Environment Agency spokesperson said where there was evidence of non-compliance ''we will not hesitate to pursue the water companies concerned, and take appropriate action".

They added that 1,300 storm overflows and storm tanks at waste water treatment works have been identified as ''spilling frequently'' and that ''a major investigation into possible unauthorised spills at thousands of sewage treatment works is ongoing".