Southern Water scores 37/100 (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 Southern Water joint 419th of 799 companies scored, and joint 9th of 11 in Water & Sewerage.
Southern Water's gross Scope 1 and 2 emissions were flat between 2022–23 and 2024–25 (152,364 t to 152,320 t, location-based), and its Scope 3 rose about 35% year on year. Its 2025–26 report shows Scope 1 and 2 of 290,160 t, mostly because the industry changed how it counts nitrous oxide from sewage treatment; without that change, Scope 1 would have risen 1.5%. The Environment Agency rated it 2 stars for 2024, with 15 serious pollution incidents, and its three-year average leakage missed its target. In 2025 it pleaded guilty to 13 offences at Margate and Broadstairs and was fined £7,127,083 in July 2026. In 2021 it was fined a record £90m for almost 7,000 unpermitted sewage discharges.
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SINK = (0.3 × Base + 0.7 × Performance) × ScaleStrongest on Carbon Footprint — Operations and Carbon Footprint — Supply Chain (7/10, 6/10). Weakest on Emissions Trajectory and Controversies & Red Flags (1/10, 2/10).
10 sources used in this assessment. All publicly available. Each row shows which rubric questions it informed.
“assured by independent consultants in accordance with the methodology of the AA1000 Assurance Standard v3”
“This requests that our suppliers provide us with details of”
“For 2024: red status for 2 metrics, amber status for 3 metrics and green status for 2 metrics”
“we recorded 269 category 1-3 pollution incidents in 2024, a 15% increase in pollution incidents compared to 2023”
“The total fine is therefore £7,127,083.”
“This year’s significant increase in Scope 1 emissions is primarily due to sector-wide updates to two carbon emission factors within the Ofwat Carbon Accounting Workbook.”
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Where Southern Water sits among water & sewerage peers.
Among the 11 major water & sewerage brands we've scored, Southern Water is tied =9th of 11, with 1 other.
As Southern Water's score updates, the trajectory will appear here.
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Southern Water Services Limited is the regulated water and sewerage company for South East England. It was incorporated on privatisation in 1989 and is headquartered in Worthing. Its filed accounts for the year to 31 March 2026 report revenue of £1,443.2m and an average of 3,109 employees. It is regulated by Ofwat and the Environment Agency.
UK water and sewerage utility; comparable scale and regulatory environment.
View breakdown →UK water and sewerage utility; similar infrastructure challenges and enforcement history.
View breakdown →UK water and sewerage utility; operates in adjacent English regions.
View breakdown →UK water and sewerage utility; regulated monopoly comparable sector position.
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