Wessex Water Services Limited is the regulated water and sewerage company for much of South West England and is part of the YTL group.
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Wessex Water reports operational and supply-chain emissions, including capital carbon. Its latest fall in emissions, from 105 to 96 ktCO2e, was attributed by the company to lower rainfall. Pollution incidents rose to 62 per 10,000 km of sewer in 2024, from 36 in 2023, against a target of 19.5, and storm overflow spills rose sharply in 2023. Ofwat confirmed an £11m enforcement package in December 2025, the company incurred a £23.5m underperformance payment for 2024–25, and in July 2024 the ASA banned a TV advert that omitted its 2-star Environment Agency rating.
Wessex Water scores 43/100 (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 Wessex Water joint 296th of 847 companies scored, and 5th of 11 in Water & Sewerage.
Where Wessex Water sits among water & sewerage peers.
Among the 11 major water & sewerage brands we've scored, Wessex Water sits 5th of 11.
Its three lowest-scoring questions, and what the evidence didn't show.
Storm overflow discharges rose to 41,453 in 2023 from 21,878 in 2022.
ASA banned Wessex Water TV advert in July 2024 for omitting 2-star EPA rating. £23.5m pollution-incident penalty in 2024-25.
Market-based Scope 2 (78,381 tCO2e) exceeds location-based (47,781 tCO2e), indicating most purchased electricity lacks renewable backing.
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 Water Impact and Controversies & Red Flags (2/10, 3/10).
The 3 companies in the sector scoring nearest above Wessex Water.
Pennon group Scope 1 and 2 emissions, assured by Jacobs, fell about 4% in 2025/26, mainly because more renewable electricity was bought for the Bristol Water region, and South West Water's electricity is backed by renewable energy certificates.
See the breakdown →United Utilities' 2025/26 market-based Scope 1 and 2 emissions were 539,041 tCO2e, including 239,498 tCO2e added by a 2026 industry update to process-emission factors.
See the breakdown →Scottish Water's operational emissions, audited to ISO 14064-1, fell from 462,000 tCO2e in 2006/07 to 220,000 tCO2e in 2024/25, and have been roughly flat for three years.
See the breakdown →The formula and all 12 sources.
Same ten questions for every company. No private weighting.
SINK = (0.3 × Base + 0.7 × Performance) × Scale12 sources used in this assessment. All publicly available. Each row shows which of the ten questions it informed.
8 of 12 sources are independent of the company.
“Carbon: Table 11A: Streamlined energy and carbon reporting, task force on climate-related financial disclosures report.”
“using the water industry's standardised Carbon Accounting Workbook since 2007.”
“Our landholding was valued at 14,348 BU.”
“Wessex Water said it had not met its targets for leakage or serious pollution incidents.”
“Ofwat has confirmed that Wessex Water will fund an £11m enforcement package after the company failed to operate, maintain and upgrade its wastewater network adequately”
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Wessex Water Services Limited is the regulated water and sewerage company for much of South West England and is part of the YTL group. It was incorporated in 1989 and is headquartered in Bath. Its filed accounts for the year to 30 June 2026 report revenue of £802.8m and an average of 2,768 employees. It is regulated by Ofwat and the Environment Agency.
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