Welsh Water under pressure as sewage pollution incidents hit ten-year high
Natural Resources Wales (NRW) has stepped up regulatory action against Dŵr Cymru Welsh Water, warning the company must make urgent and fundamental changes to its operations after recording its highest number of sewage pollution incidents in a decade.
New figures published today show Welsh Water was responsible for 155 pollution incidents in 2024, including 132 linked to sewerage assets—a sharp rise from 89 in 2022 and 107 in 2023. The data reveals a 42% increase in sewage-related incidents over the past ten years, with the majority traced to foul sewers (423 incidents), storm overflows (168), and water treatment works (166).
“We’ve seen a huge deterioration in performance since 2020,” said Nadia De Longhi, Head of Regulation and Permitting at NRW. “Despite repeated warnings and interventions, Welsh Water has been unable to reverse this concerning trend.”
Storm overflow data shows widespread failures
Alongside the pollution incident report, NRW also published its 2024 storm overflow spill data, revealing 112,589 spills lasting a combined 929,168 hours across Wales. While slightly down from 2023’s record-breaking 121,422 spills, the figures still reflect widespread operational failures.
Analysis by Afonydd Cymru found that the top 20 most frequently spilling assets operated within legal limits—defined as rainfall exceeding 4mm per hour—for just 1% of the time. In total, 276 assets spilled for more than 1,000 hours, far exceeding thresholds that could be considered compliant under exceptional rainfall conditions.
The worst-affected catchments included the Ogmore, Loughor, and Clydach, with many spills linked not to sewer blockages but to failures at wastewater treatment works, including inadequate storm tank capacity and failure to fully treat incoming sewage.
“Our priority is to prevent environmental damage before it happens,” said De Longhi. “We will be clamping down on unpermitted storm overflows and introducing tighter criteria for annual reporting.”
Natural Resources Wales vehicle
(Image: NRW)Enforcement and investment
NRW has already pursued multiple prosecutions against Welsh Water, including cases linked to pollution on the Gwent Levels and a tributary of the Afon Llwyd. Officials say enforcement is not the preferred route, but necessary when preventative measures fail.
The regulator has secured record levels of environmental investment through the 2025–2030 Ofwat price review, and introduced new guidance on storm overflow permits to tighten compliance.
In 2025, NRW will launch a dedicated team to increase monitoring of discharges, carry out compliance checks and audits, and implement Pollution Incident Reduction Plans with annual improvement targets. A new framework for performance assessments—developed jointly with the Environment Agency—will come into force in January 2026.
“We will be clamping down on unpermitted storm overflows and introducing tighter criteria for annual reporting,” said De Longhi. “Our priority is to prevent environmental damage before it happens.”
The latest figures follow a landmark case earlier this year in which Dŵr Cymru Welsh Water was fined £1.35 million for more than 800 breaches of its sewage discharge permits across Wales and Herefordshire. The offences, which took place in 2020 and 2021, were linked to failures in self-monitoring and data reporting—issues that NRW said were avoidable and indicative of deeper systemic problems. The regulator has since downgraded Welsh Water’s environmental performance rating to two stars, citing a continued decline in compliance and transparency.
Meanwhile, public frustration is mounting. Residents in Gower have staged protests at wastewater treatment sites, demanding action over repeated spills near popular beaches like Brandy Cove and Caswell. Campaigners say the discharges are harming water quality, threatening tourism, and putting public health at risk. Welsh Water has pledged £2.5 billion in environmental investment between 2025 and 2030, but critics argue that rising water bills—set to increase by 42% by 2030—should come with greater accountability and faster infrastructure upgrades.
A Dŵr Cymru Welsh Water spokesperson said:
“We acknowledge the concerns raised in the report and accept that while the number of serious pollution incidents has slightly reduced, our performance is not where it needs to be. The industry across the UK has seen increases in pollution incidents.
“We are rightly being held to a higher standard and have improved our processes to meet this challenge, with better monitoring leading to detecting more short-lived event and better reporting.
“We are accelerating investment in key areas to reduce pollution incidents with a £4bn investment programme that includes £2.5bn on environmental projects.
“While we have made progress, such as increasing the number of incidents we find and self-reporting, we know more needs to be done.
“We remain committed to working constructively with NRW to deliver improvements and will be engaging closely on their new requirements and guidance, including the development of Pollution Incident Reduction Plans and further use of smart technology to spot problems in the sewer network before they can cause a pollution.”
NRW’s full Environmental Performance Report for Welsh Water, including updated star ratings, will be published this autumn.
Related stories from Swansea Bay News
Welsh Water fined £1.35m for over 800 breaches to sewage discharge permits
Published March 2024: Water company handed record fine after admitting widespread permit breaches across Wales.
Bumper water bills set for Welsh Water customers
Published April 2024: Customers face steep bill increases as company seeks to fund environmental upgrades and infrastructure repairs.
Campaigners in Wales join national protest against plastic pollution ahead of global treaty talks
Published May 2024: Environmental groups call for stronger protections for rivers and coastlines, including action on sewage and microplastics.
Residents say they’re ‘pooped off’ with Gower sewage spills
Published June 2024: Locals raise concerns over repeated discharges near popular beaches, calling for tougher enforcement and transparency.
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