Thames Water scores 36/100 (Below expectations) on SINK's independent climate assessment — scored from public data only, no company payment can change a number. Last verified October 2026.
That places Thames Water joint 439th of 799 companies scored, and 11th of 11 in Water & Sewerage.
The Environment Agency rated Thames Water 1 star ('poor performing company') for 2024, and in 2025 Ofwat imposed a record £122.7m penalty. In 2025/26 it had 24 serious pollution incidents, discharge permit compliance of 88.22% and average leakage of 573.7 Ml/d. No third-party assurance of its greenhouse gas figures was found. Its zero market-based Scope 2 relies on supplier renewable electricity, and its reported Scope 3 covers operational categories only, with no capital carbon.
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SINK = (0.3 × Base + 0.7 × Performance) × ScaleStrongest on Carbon Footprint — Operations and Energy Source (6/10, 6/10). Weakest on Water Impact and Controversies & Red Flags (1/10, 2/10).
9 sources used in this assessment. All publicly available. Each row shows which rubric questions it informed.
“In 2025/26 the water sector, in agreement with industry regulator Ofwat, has adopted an updated emissions factor for nitrous oxide”
“Includes fossil fuels, site process and fugitive emissions and vehicle transport (Fleet).”
“In 2024/25 we self-generated and used 475.3GWh of renewable energy, covering 25.8% of our own energy needs.”
“RWE will supply a total of 132 gigawatt hours (GWh) of clean electricity annually”
“33 serious incidents – this is rated as red”
“Thames Water has been fined £122.7 million after two investigations into wastewater and dividend payments, in the largest penalty Ofwat has ever issued”
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Thames Water sits at the bottom of the water & sewerage pack.
Among the 11 major water & sewerage brands we've scored, Thames Water sits 11th of 11.
As Thames Water's score updates, the trajectory will appear here.
This score is not currently being contested.
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Thames Water Utilities Limited supplies water and sewerage services to London and the Thames Valley. It was formed on privatisation in 1989 and is headquartered in Reading. Its filed accounts for the year to 31 March 2026 report revenue of £3,756.5m, including £140.9m passed through for the Thames Tideway Tunnel, and an average of 8,472 permanent employees. It is regulated by Ofwat and the Environment Agency.
Direct sector peer; English water and sewerage operator under same Ofwat regulation.
View breakdown →Direct sector peer; English water and sewerage operator serving eastern England under Ofwat oversight.
View breakdown →Direct sector peer; English water and sewerage company regulated by Ofwat; major river system operator.
View breakdown →Direct sector peer; English water and sewerage company regulated by Ofwat; north-west regional operator.
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