Dŵr Cymru/Welsh Water have been slammed once again after the industry regulator found "serious and unacceptable" breaches in the supplier's sewage and network services.

A £40 million penalty, imposed by industry regulator Ofwat, was supplemented by a £4.1 million package to improve river quality.

Responding to Ofwat’s announced enforcement package for Dŵr Cymru, Plaid Cymru spokesperson for Climate Change Delyth Jewell MS said: “People are fed up of more and more sewage being dumped into our waterways while companies face little consequences.

“While water bills are becoming steeper, our water quality is becoming poorer - and yet those in charge of the system are being rewarded with huge bonuses. The current system isn't working and it's about time water companies were held accountable.

“Plaid Cymru will present a new water bill for Wales that will allow us to strengthen the regulatory system and fix this broken system - improving water quality, tackling pollution, and ensuring affordability for households the long-term.”

Welsh Conservatives Senedd Member Andrew RT Davies has also condemned the company, warning that customers could face higher bills as a consequence.

He said it would be unacceptable if the firm reported profits while passing the cost of the fine onto hard pressed consumers.

Dŵr Cymru reported an £8 million loss in the last financial year, but made a £46 million profit the year before.

Mr Davies also said Senedd ministers’ environmental regulator Natural Resources Wales (NRW) had serious questions to answer over its failure to regulate the sewage scandal properly.

He reiterated his calls for the “unfit for purpose” NRW to be closed and replaced.

Mr Davies remarked: “It’s unacceptable that Wales’ main water supplier Dŵr Cymru has again been fined for sewage breaches.

“The firm has reported significant profits in recent years –if consumers end up footing the bill for this fine it will be unconscionable.

“Senedd ministers’ sewage regulator Natural Resources Wales also has serious questions to answer – it’s not fit for purpose and should be closed and replaced.”

A spokesperson for Ofwat said: “In response to our minded-to document, Dŵr Cymru put forward proposed undertakings under section 19 WIA91, setting out details of steps it will take to address the non-compliance we have identified to secure its future compliance.

“The undertakings also set out details of a proposed redress package valued at £44.72m. This will be funded by the company rather than customers.”

Lynn Parker from Ofwat added: "Our investigation has found serious and unacceptable breaches in how Dŵr Cymru/Welsh Water has operated and maintained its sewage works and networks, which has resulted in excessive spills from storm overflows to the environment.

“We now expect them to focus on putting things right so that customers can regain trust in their water company and the critical service they provide.

“The enforcement package will also tackle groundwater entering the sewer network - a major cause of frequent spills - and the money towards improving river quality will be spent in ‘extremely sensitive’ catchments.”

A spokesperson for Dŵr Cymru said: “We accept the findings of Ofwat’s investigation and apologise for where we have fallen short of the standards that our customers and regulators rightly expect from us.

“We have started a major transformation programme across the company, including within our wastewater services, focused on improving performance, strengthening operational oversight and accelerating investment to deliver better outcomes for rivers and coastal waters.

“The investigation has considered both historic and more recent compliance, and we accept that improvements are needed. We have already taken steps to strengthen our governance, oversight and compliance arrangements as part of a wider transformation programme across the business.

“We have also agreed a £44.7 million redress package with Ofwat which will direct funding towards environmental improvements and actions to reduce the impact of storm overflows.

“As part of this package, nearly £40.6 million will fund additional work to reduce spills from specific storm overflows and tackle groundwater entering the sewer network — a major cause of frequent spills. This will include targeted investment at priority sites as well as investigations and improvement work on parts of the sewer network to reduce infiltration.

“A further £4.1 million will be invested to help improve river water quality in extremely sensitive catchments. This will include establishing a new £1 million Cymuned Natur Fund to support community groups and charities across our operating area that are working to protect and enhance the natural environment.

“These actions are in addition to the £4.2 billion we are investing between 2025 and 2030, including £2.5 billion dedicated to environmental improvements — with £889 million specifically targeted at improving storm overflows.”

A consultation on the package is now open to the public and key stakeholders until 2 April to offer any comments and responses before Ofwat announces its final decision.