Dŵr Cymru Welsh Water sustainability score: 37/100
Making progress starts at 46. The highest score on SINK is 71.
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.
More about Dŵr Cymru Welsh Water
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.
Founded 1989Head office Cardiff, United KingdomStaff ~4,056Revenue £1,169.8M (FY2025/26, year to 31 March 2026)Website ↗
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. Scores are free. Nobody can pay to change a score, speed it up or hide it. Last verified October 2026.
That places Dŵr Cymru Welsh Water joint 507th of 1,023 companies scored, and joint 9th of 11 in Water & Sewerage.
What is Dŵr Cymru Welsh Water doing well, and where does it fall short?
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).
Where Dŵr Cymru Welsh Water lost points
For each question that lost points, the evidence our public rubric looks for that we didn't find.
What would raise this score
- Whether its emissions are fallingShow its emissions are falling.
- Its effect on waterPublish figures for its water use.
- Its effect on natureAssess its effect on nature and publish a basic environmental policy.
Every question that lost points
- Emissions from its own operations8/10No verified figures published with their method and a falling trend.
- Emissions from its supply chain6/10No full value-chain map or supplier engagement programme.
- Whether its emissions are falling1/10No evidence its emissions are falling.
- How clean its energy is5/10Less than half its energy shown to be renewable, or no transition plan.
- Its effect on nature3/10No assessment of its effect on nature, and no basic environmental policy.
- How it uses materials and handles waste3/10No active waste reduction, reuse or repair shown.
- Its effect on water1/10No figures for its water use.
- Its climate targets3/10No specific targets with dates.
- How openly it reports6/10No annual impact report, or no pay linked to climate targets.
- Its record on controversies3/10Points deducted for controversies or its business model. The finding is under question 10.
A score changes when the evidence does. We use new published evidence at the next rescore. Anyone can send us new evidence, free. How to send it.
How is Dŵr Cymru Welsh Water's SINK score calculated?
Same ten questions for every company. No private weighting.
SINK = (0.3 × Base + 0.7 × Performance) × ScaleWhat evidence is Dŵr Cymru Welsh Water's score based on?
10 sources used in this assessment. All publicly available. Each row shows which of the ten questions it informed.
30% of them were published by Dŵr Cymru Welsh Water itself; the rest come from independent sources.
“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.
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How does Dŵr Cymru Welsh Water compare with other water & sewerage companies?
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.
Who scores higher in Water & Sewerage?
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 →Which companies moved this week, and why.
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