Ofwat is set to probe all 11 water firms in England and Wales as part of an investigation into sewage spills.

It will be looking into whether their sewage treatment works are polluting the environment.

Ofwat initially opened this investigation in November 2021 and has handed out around £300 million in fines to those who were found to have breached their legal obligations.

It has recently announced formal enforcement notices have been served on Dwr Cymru Welsh Water, Hafren Dyfrdwy, Severn Trent and United Utilities.

The regulator has already taken out enforcement cases against Anglian Water, Northumbrian Water, South West Water, Thames Water, Wessex Water and Yorkshire Water, with extensive investigations ongoing.

Therefore, this means Ofwat has enforcement cases with all 11 of England and Wales' water firms.

What this means is that the water regulator has gathered evidence and found the firms may have breached their obligations to protect the environment, which could lead to fines.

Ofwat 'concerned' about sector’s environmental performance

Alongside all of this, Ofwat is also still monitoring Southern Water following a previous enforcement case in 2019.

David Black, Ofwat’s chief executive, said: “The fact that Ofwat now has enforcement cases with all 11 of the wastewater companies in England and Wales demonstrates how concerned we are about the sector’s environmental performance.

“This is the largest and most complex investigation Ofwat has undertaken.”

Mr Black added that they were keen to conclude cases quickly so that the firms could focus on its latest plan to “deliver cleaner rivers and seas”.

Both United Utilities and Severn Trent have responded to the enforcement notices, saying they would work with Ofwat in its investigation.

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Meanwhile, a spokeswoman for the Government’s Environment Department said: “We will never look the other way while water companies pump sewage into our waterways. That is why we welcome the enforcement action announced today.

“The new Government will go even further to clean up Britain’s rivers, lakes and seas.”

Last week, new Prime Minister Sir Keir Starmer said the Government will need to “get to grips with” sewage and pollution, while Environment Secretary Steve Reed proposed new measures to reform the sector and “fix our broken sewage system”.