Ofwat has expanded its investigation into wastewater treatment meaning all 11 water and wastewater companies in England and Wales are now facing scrutiny over sewage spills.

The water regulator has opened enforcement cases into four more companies – Dŵr Cymru Welsh Water, Hafren Dyfrdwy, Severn Trent and United Utilities – in relation to the operation of their wastewater businesses.

The four firms have joined Anglian Water, Northumbrian Water, South West Water, Thames Water, Wessex Water, and Yorkshire Water, after enforcement cases were launched against these six companies in 2022, with the investigations still ongoing.

Southern Water remains subject to enforcement monitoring following a previous enforcement case in 2019.

Ofwat suggested that while it still has “concerns” to investigate, it also noted that opening an enforcement case does not automatically imply the company has breached their legal obligations.

Chief executive at Ofwat, David Black, 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.

“Where we find that companies have breached their obligations, we will continue to act – over recent years, we have imposed penalties and payments of over £300m on water and wastewater companies.”

One of the latest companies to face an investigation, Severn Trent, recently announced a programme to significantly reduce its use of storm overflow.

Ofwat, which said it welcomed this move, also confirmed that its investigations will “consider both current and past performance”, as well as “reflect on the steps” that companies are taking when determining the necessary action.

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

“Ofwat is committed to concluding these cases as quickly as possible, so that the sector can focus on delivering the £88bn expenditure PR24 will unlock to deliver cleaner rivers and seas. As part of this package of investment, £10bn is earmarked to tackle storm overflows with a target to reduce spills from storm overflows by 44%.”

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