Water companies hold a critical position in safeguarding both environmental and public health. Concern over the pollution of our waterways has been building, and as such, scrutiny of water company practices has become more stringent.
Despite ongoing investment to improve services, the environmental and financial performance of Dŵr Cymru – Wales’ largest water company – has declined in recent years. On Wednesday 5 November 2025, the Senedd Climate Change, Environment, and Infrastructure (CCEI) Committee scrutinised Dŵr Cymru executives on its recently announced major transformation programme, which is internally referred to as 'Trawsnewid'.
The timeline below highlights key recent developments in with regard to Dŵr Cymru’s environmental and financial performance, and how regulators and parliaments have responded.
23 October 2025
Ofwat’s 2024-25 Water Company Performance Report ranked Dŵr Cymru as “lagging behind" for the fourth consecutive year. It was performing poorer than its target in seven of twelve categories.
23 October 2025
Natural Resources Wales (NRW) maintains Dŵr Cymru’s two-star (‘company requires improvement’) environmental performance rating for a third consecutive year. It says 2024 saw its highest number of pollution incidents in a decade, although it improved its incident reporting and compliance with permitted discharges.
11 September 2025
Dŵr Cymru announces the Trawsnewid programme – an 18-24 month “transformation programme” involving a company restructure and the loss of around 500 jobs.
28 February 2025
Dŵr Cymru’s 2024 storm overflow data submission shows a 7% decrease in total hours of spillage compared to the previous year, which it attributes to lower rainfall levels.
17 and 18 February 2025
Dŵr Cymru’s credit rating is downgraded by the ratings agencies Fitch and Moody’s
19 December 2024
Ofwat’s for 2025-30 permits Dŵr Cymru to spend £6bn, including more than £1bn to improve storm overflows.
These investments will be funded by customer bills. Consequently, average bills rose by 27% in 2025, and will see an overall 42% increase by 2030.
21 November 2024
Ofwat intervenes to block Dŵr Cymru from using customer funds to pay £163,000 in executive bonuses.
23 July 2024
NRW described a “further decline” in Dŵr Cymru’s environmental performance, with an increase in the number of serious pollution incidents. However, the company’s retained a 2-star (‘company requires improvement’) environmental rating.
14 March 2024
In an investigation by Ofwat into Issues identified and self-reported by Dŵr Cymru on its performance on leakage and per capita consumption (PCC) data, Dŵr Cymru was found to have misled customers and regulators and ordered to pay a redress package of £40m to customers.
29 February 2024
Dŵr Cymru’s 2023 Event Duration Monitor (EDM) data sent to Natural Resources Wales (NRW). These record the number of times and duration storm overflows have operated.
The data is reported to show 105,943 spills, 93% of which were ranked "significant", and that storm overflows were operating for over 916,000 hours.
Dŵr Cymru said the higher number of spills was a result of wet weather in 2023, as storm overflows are designed to operate when too much rainwater enters the system.
8 February 2024
The CCEI Committee published its Report on performance of Dŵr Cymru. It called for Dŵr Cymru to:
- explain how it’s planning for future climate pressures to mitigate serious pollution incidents;
- commit to setting a more stretching target for reducing pollution incidents by 2030; and
- commit to an ambition of zero pollution incidents in the shortest time possible.
The Welsh Government, Ofwat, NRW and Dŵr Cymru have responded.
22 November 2023
The UK Parliament’s Welsh Affair’s Committee took further evidence in its inquiry on water quality in Wales.
Campaigners (including Prof. Peter Hammond), NRW, Ofwat and Dŵr Cymru discussed reports of illegal untreated wastewater spillages other issues.
9 November 2023
The CCEI Committee took evidence from Dŵr Cymru, NRW and Ofwat on the continued rise in sewer overflows operating outside of their permit conditions.
Dŵr Cymru was scrutinised over its recent environmental performance, and reported analysis showing numerous permit breaches across Wales. NRW was scrutinised over its response to those incidences.
24 October 2023
The Wales Better River Water Quality action plans were updated to show progress against the actions.
23 October 2023
Ofwat’s Water Company Performance Report ranked Dŵr Cymru as “lagging”. Dŵr Cymru will have to return money to customers through cutting bills as a result.
19 October 2023
It was reported that Dŵr Cymru had “admitted illegally spilling untreated sewage at dozens of treatment plants for years”.
The analysis of Dŵr Cymru data was undertaken by Professor Peter Hammond from campaign group Windrush Against Sewage Pollution (WASP). It showed “2,274 days with permit breaches involving discharges of untreated sewage” from 2018 to 2023.
In response, Dŵr Cymru confirmed plans to accelerate investment to improve water quality, including £20m investment in new wastewater treatment works at Cardigan, which had been identified as one of the worst performing sites.
2 October 2023
Dŵr Cymru submitted its proposed Business Plan for 2025-30 to Ofwat.
If approved, Dŵr Cymru will invest nearly £1.9 billion in the environment between 2025 and 2030 – 84% more than across 2020-25. However this amount has since increased to include additional environmental expenditure, alongside a proposed increase in the average annual customer bill.
25 July 2023
CCEI wrote to Dŵr Cymru expressing concern at its decline in environmental performance.
Dŵr Cymru responded with explanations for the decline . It said that the “drought and high temperatures experienced in 2022 should be taken into account when assessing our pollution performance”.
12 July 2023
NRW downgraded Dŵr Cymru to a 2-star (requires improvement) rating (maximum possible is 4-star) following a further decline in environmental performance.
NRW reported that pollution incidents rose by 7% in 2022, and that Dŵr Cymru caused 89 sewage pollution incidents (84 of these were categorised as having a low environmental impact, five were classed as having a high or significant impact).
Dŵr Cymru’s self-reporting of pollution incident performance also saw a deterioration of 7% compared to 2021, with only 69% of pollutions incidents self-reported in 2022.
15 March 2023
The UK Parliament’s Welsh Affairs Committee held two evidence sessions looking at water quality in Wales with campaigners, water companies and Ofwat.
The Chair of the Committee, Rt Hon Stephen Crabb MP, called for greater urgency to prevent further damaging sewage discharges.
5 July 2022
The Welsh Government set up the Wales Better River Quality Taskforce to “to evaluate the current approach to the management and regulation of overflows in Wales and to set out detailed plans to drive rapid change and improvement”.
Five action plans were published for the areas identified as requiring additional action.
Early 2022
In response to public outcry over sewage discharges, the CCEI Committee undertook an initial investigation into sewer overflows and their impact on water quality.
It made number of recommendations to Dŵr Cymru, focused on enhanced monitoring and reporting of sewage spills and their impact.
In response, Dŵr Cymru recognised that “more needs to and can be done to reduce the amount of discharges from CSOs [Combined Sewer/storm Overflows]”.
Further details can be found in this Senedd Research article.
Article by Lorna Scurlock and Dr Matthew Sutton, Senedd Research, Welsh Parliament
