A sewage treatment work investigation has been announced by Ofwat to open enforcement cases against five companies including Thames Water.

The aim of the investigation is to see how companies manage their wastewater treatment works.

Anglian Water, Northumbrian Water, Thames Water, Wessex Water, and Yorkshire Water have been served formal notices to gather further information for enforcement purposes.

It comes after an analysis by Ofwat in December 2021, as companies were asked to submit information about their sewage treatment works and what they are doing to resolve any issues.

The five companies are targeted as the information they provided in December raised one or more of the following concerns:

• It reported a significant number of wastewater treatment works which the company considers might not be compliant with its environmental permits.

• It raised concerns about how overall the company manages its compliance with its environmental obligations.

• It didn't sufficiently show how the company have established whether its treatment works are meeting the requirements of its environmental permits, and so we need further information for our assessment.

David Black, Ofwat interim chief executive, said: “The data that emerged at the end of last year suggested widespread shortcomings in how water companies were running sewage treatment works.

“The first phase of our investigation suggests those concerns are credible.

"We have identified shortcomings in most water and wastewater companies and are continuing to investigate.

“But we have already seen enough in five companies to cause serious concern and warrant us taking further action.

"We will now dig deeper into what these five companies have been doing, with the prospect of formal enforcement against them if we find they are failing on obligations Ofwat enforces.

"We will have further questions for all companies on this. In the meantime, we expect them to make quick progress in addressing any potential non-compliance they might have, whilst strengthening how they manage their environmental obligations as a whole."

All water and sewerage companies in England and Wales remain subject to the ongoing investigation as Ofwat continues to review information it has gathered.

Ofwat will keep the enforcement cases under review, and the companies in focus may change as new information comes to light.

The regulator can fine companies up to 10 per cent of their annual turnover.

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