Ofwat’s investigation has looked into whether the three companies have been providing customers with the level of service they are entitled to under the law.
It has found the three companies failed to adequately invest in and maintain their networks, leading to repeated releases of raw sewage into the country’s waterways.
On Tuesday it proposed fines of £47m for Yorkshire Water and £17m for Northumbrian Water. For Thames Water it is proposing the largest fine on record of £104m.
The regulator’s chief executive, David Black, said: “Ofwat has uncovered a catalogue of failure by Thames Water, Yorkshire Water and Northumbrian Water in how they ran their sewage works and this resulted in excessive spills.”
This announcement follows a BBC investigation earlier this year that revealed sewage had potentially been released illegally 6,000 times in 2022 by England’s water companies in breach of their permits.
Releasing raw sewage has the potential to significantly damage the environment and poses a risk to human health for those swimming in a river or sea where sewage is being discharged.
Ofwat can fine companies up to 10% of their annual sales. In the case of Thames Water, the proposed fine is 9% of sales, which Mr Black told the BBC “reflects the severity of the offences”.
The regulator found that more than two-thirds of Thames Water’s wastewater treatment works had operational issues, and that most of Yorkshire Water’s wastewater treatment works had regularly spilled sewage into the environment since 2018 pointing to a “systematic issue”.
A Thames Water spokesperson said: “We take this matter very seriously and have cooperated at every stage of Ofwat’s investigation. We regard all untreated discharges as unacceptable, even when they are permitted.”
Yorkshire Water and Northumbrian Water said they were disappointed by Ofwat’s decision.
Ofwat continues its investigations into a further eight water and wastewater companies in England and Wales for similar issues, with further updates expected in the coming year.
“For too long, failure to invest in our vital water infrastructure has been unchecked,” said Tessa Wardley, director of advocacy at environmental charity Rivers Trust.
“It seems highly likely that there is more to come when investigations into the other eight water companies is concluded.”
