Dŵr Cymru Welsh Water is the water and sewerage company for most of Wales and parts of England, owned since 2001 by Glas Cymru.
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Dŵr Cymru Welsh Water's total market-based emissions rose 9% to 443.4 kt in 2025/26, and its emissions targets are under review. Natural Resources Wales recorded 155 pollution incidents in 2024, the highest in a decade, and kept the company at two stars ('requires improvement') for a third year. In 2025 it was sentenced in four criminal cases under environmental permitting rules. Ofwat ordered £40m of redress for misleading leakage and consumption data in 2024 and proposed a £44.7m enforcement package in March 2026.
Dŵr Cymru Welsh Water scores 37/100 (Below expectations) on SINK's independent climate assessment, scored from public data only. Fees pay for the review, never the result. Last verified October 2026.
That places Dŵr Cymru Welsh Water joint 435th of 847 companies scored, and joint 9th of 11 in Water & Sewerage.
Where Dŵr Cymru Welsh Water sits among water & sewerage peers.
Among the 11 major water & sewerage brands we've scored, Dŵr Cymru Welsh Water is tied =9th of 11, with 1 other.
Its three lowest-scoring questions, and what the evidence didn't show.
Gross market-based emissions rose 9% from 405.9 kt (FY25) to 443.4 kt (FY26); location-based rose to 519.7 kt.
Sewage incidents rose from 89 (2022) to 132 (2024).
No TNFD disclosure found.
A score changes when the evidence does. We use new published evidence at the next rescore. Evidence that isn't public can count through an evidence review.
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Get in touch →Strongest on Carbon Footprint — Operations and Carbon Footprint — Supply Chain (8/10, 6/10). Weakest on Emissions Trajectory and Water Impact (1/10, 1/10).
The 3 companies in the sector scoring nearest above Dŵr Cymru Welsh Water.
Northumbrian Water's net market-based operational emissions fell from 68.6 to 15.9 ktCO2e between 2019/20 and 2024/25, relying on renewable electricity and gas certificates, while gross location-based emissions moved from 163.3 to 152.6 kt.
See the breakdown →Anglian Water's gross reported emissions rose from 265,219 to 297,156 tCO2e between 2022/23 and 2024/25.
See the breakdown →Yorkshire Water's market-based emissions rose from 281 to 295 ktCO2e between FY2024 and FY2025, and Scope 1 rose from 85 to 88 kt.
See the breakdown →The formula and all 10 sources.
Same ten questions for every company. No private weighting.
SINK = (0.3 × Base + 0.7 × Performance) × Scale10 sources used in this assessment. All publicly available. Each row shows which of the ten questions it informed.
“The emissions data on page 25 has been verified by an independent third party.”
“Separately from the CAW, Welsh Water have undertaken their own estimates & studies on the emissions associated with the purchase of Capital Goods & Services”
“the company was responsible for a total of 155 pollution incidents during 2024 – 132 from sewerage assets and 23 relating to water supply.”
“Samples collected by officers found ammonia levels to be significantly over the 1.1mg/L threshold for a SSSI.”
“It says 2024 saw its highest number of pollution incidents in a decade”
“The generation will be equivalent to around 3% of Welsh Water’s annual electricity use”
“align with our goal of energy neutrality by 2050”
If you believe a source has been misread or a newer version exists, submit a challenge.
Dŵr Cymru Welsh Water is the water and sewerage company for most of Wales and parts of England, owned since 2001 by Glas Cymru. It was incorporated in 1989 and is headquartered in Cardiff. Its filed accounts for the year to 31 March 2026 report revenue of £1,169.8m and an average of 4,056 employees. It is regulated by Ofwat and Natural Resources Wales.
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