Six English water companies are facing legal action over allegations they under-reported pollution discharges and overcharged customers as a result.
Professor Carolyn Roberts, an environmental and water consultant, said she is planning to bring a string of cases to the Competition Appeal Tribunal in a bid to secure more than £800m compensation on behalf of 20 million customers.
She claims the companies failed to disclose the number of sewage discharges, resulting in households being “unfairly overcharged”.
Professor Roberts, who is represented by Leigh Day Solicitors, is bringing her first claim – estimated to be worth £330m – against Severn Trent Water, which serves eight million people across the Midlands and parts of Wales.
It follows claims from campaigners that the River Severn is the most polluted in the UK. They estimate waste was pumped into the waterway on 2,600 separate occasions in 2021.
Professor Roberts also plans to take action against Thames Water, United Utilities, Anglian Water, Yorkshire Water and Northumbrian Water.
There has been growing public anger over sewage being pumped into Britain’s rivers and seas, prompting industry body Water UK to issue an unprecedented public apology earlier this year for not acting quickly enough on spills.
The organisation’s chair Ruth Kelly also admitted that campaigners had been “right to be upset about the current quality of our rivers and beaches”.
The government has also promised to crack down on the issue and is said to be considering unlimited fines for firms caught polluting.
However, Water UK described Professor Roberts’s legal action as “highly speculative” and “entirely without merit”, while Severn Trent said her claims were “completely wrong”.
But Professor Roberts claimed the water companies had broken competition laws by misleading the Environment Agency and regulator Ofwat.
She added: “Like many others across the country, I have viewed with horror the escalating number of stories in the media regarding the volume of sewage discharged into our waterways and onto our beaches.
“It appears that because of the serial and serious underreporting at the heart of these claims, water companies have been avoiding being penalised by Ofwat.
“I believe this has resulted in consumers being unfairly overcharged for sewage services.”
Leigh Day said it was the first environmental collective action case of its kind.
It said anyone who has paid a water bill to one of the companies from April 2020 onwards – or April 2017 in the case of Severn Trent – might be entitled to come forward and claim compensation if the case is successful.
The firm said it expected any potential payouts to be funded by the firms and their shareholders – and not from higher bills for customers.
Zoe Mernick-Levene, a partner at Leigh Day, said: “These claims are hugely significant.
“Not only is compensation being sought for millions of customers who have and continue to pay higher water bills, but we hope that it will also send a message to water companies that they cannot unlawfully pollute waterways and mislead their regulators without consequence.”
A Water UK spokesperson said: “This highly speculative claim is entirely without merit. The regulator has confirmed that over 99% of sewage works comply with their legal requirements.
“If companies fail to deliver on their commitments, then customer bills are already adjusted accordingly.”
A spokesperson for Severn Trent said: “This is a highly speculative claim with no merit which we strongly refute.
“Should pollutions ever occur, they are always reported to the Environment Agency. Any claim to the contrary is wholly and completely wrong.”