An investigation by the Panorama programme aired on the BBC last night said it had found that water companies have been illegally dumping untreated sewage into rivers in England and Wales.

According to detailed data analysed by Panorama gathered via environmental information requests for information on a handful of sewage works from 10 water companies in England and Wales, some companies have regularly breached the conditions in their permits.

The investigators on the programme concluded that the data suggested seven of the 10 companies had treatment works that were breaching their permits by dumping sewage before they were treating the specified volumes.

The investigation found evidence that one company had provided incorrect information to the Environment Agency about the sewage it was discharging into the river and another water company which was discharging sewage without a permit.

Welsh Water was named as one of the worst offenders – according to Panorama, the data shows three of its treatment works were in breach of their permits. The programme claimed that the not-for-profit company’s Aberbaiden plant had illegally discharged untreated sewage on 12 consecutive days in December into the River Usk and had also been using a sewage overflow pipe on the river which did not have a permit.

Welsh Water told Panorama it did not accept its sites were operating illegally and that it hoped to have a permit in place for the overflow pipe by July. A statement issued by the water company said:

“As a not for profit company so closely linked to the environment, we are very aware of the impact our operations can have on our surroundings and take our environmental performance very seriously. …

“Our network also includes combined storm overflows (CSOs) which play an essential role in stopping sewage from backing up into customers’ properties during periods of heavy rain. They usually release storm waters into rivers or the sea and their operation is highly regulated and closely monitored by our regulator Natural Resources Wales.

“Whilst CSOs are mainly operating as designed and permitted, we recognise that with environmental legislation tightening and customer expectations changing, more needs to be done. However, this requires significant additional funding and will take many years to deliver.”

Welsh Water said it had invested £8.1 million in improving the monitoring of the CSOs since 2015, and now had spill monitors on 96.7% of all of its CSOs – more than any other water company.

Thames Water’s Mogden treatment works in south-west London which treats waste from more than two million people in the city was also highlighted in the programme.

Panorama said the data showed the water had been illegally discharging billions of litres of untreated sewage and had breached its permit on 43 days in 2020. Thames Water told the programme that a small number of its sewage works had struggled following periods of heavy rainfall and that it was investing heavily to improve them, commenting:

"Putting untreated sewage into rivers is unacceptable to us, to our customers and to the environment, even when legally permitted." 

"We absolutely want to go further, invest more, and play our part in helping the environment to thrive."

Panorama also investigated Yorkshire Water’s Wetherby treatment works and said the utility had failed to report sewage spills into the River Wharfe to the Environment Agency.

Yorkshire Water commented:

"We have not misled the Environment Agency, this is a single data anomaly within a very large set of data and we will certainly investigate what has happened here. There is a process for correcting submitted data with the Environment Agency and if it is found that there has been an unreported discharge we will report this in due course."

The water companies' use of Combined Sewer Overflows to discharge untreated wastewater has become a high level issue at public, regulatory and political level.

Data released by the Environment Agency at the start of April have revealed that the ten water and wastewater companies in England and Wales discharged raw sewage into rivers in England more than 400,000 times for more than three million hours last year.

In March the Government confirmed that new measures to cut water companies' reliance on storm overflows to discharge sewage into rivers are to become law.

Water UK - “Water companies have an important role but we need others to play their part"

Responding to the Panorama report on river pollution, a Water UK spokesperson said:

“Water companies are passionate about their role as custodians of our natural world, and are investing £5 billion on environmental improvements including £1.1bn on improvements to storm overflows. This includes more monitoring of overflows, investment in wastewater treatment works and using natural alternatives and the latest technology to keep sewage out of rivers and take pressure off wastewater networks.

“Water companies have an important role but we need others to play their part. This is a complex issue and the pollution that harms our rivers comes from a wide range of sources– including from agriculture, mining, roads and heavy industry. Collaboration is vital and is already underway through initiatives such as the Government’s Storm Overflows Taskforce which aims to find a long-term solution to the use of overflows.

“As the programme made clear, water companies face a huge challenge dealing with wet wipes and other items being flushed down toilets. Water UK research shows around 40% of pollution incidents may be the result of some kind of blockage in the sewer, and we know that wet wipes are a leading cause of that. Everyone plays a role in improving the health of our rivers and bringing about the long-term change we all want to see.”

Click here to access the Panorama programme The River Pollution Scandal