Southern Water sustainability score: 37/100
Making progress starts at 46. The highest score on SINK is 71.
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.
More about Southern Water
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.
Founded 1989Head office Worthing, United KingdomStaff ~3,109Revenue £1,443.2M (FY2025/26, year to 31 March 2026)Website ↗
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.
Southern 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 Southern Water joint 507th of 1,023 companies scored, and joint 9th of 11 in Water & Sewerage.
What is Southern Water doing well, and where does it fall short?
Strongest on Carbon Footprint: Operations and Carbon Footprint: Supply Chain (7/10, 6/10). Weakest on Emissions Trajectory and Water Impact (1/10, 2/10).
Where Southern 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 waterMonitor its water use and take measures to reduce it.
- Its record on controversiesDeal with the findings under question 10, in public.
Every question that lost points
- Emissions from its own operations7/10Its own emissions aren't independently verified or tracked over several years.
- 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 is4/10Less 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 waste4/10No measurable waste or recycling targets reported publicly.
- Its effect on water2/10No monitoring of water use, or no measures to reduce it.
- 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 controversies2/10Points 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 Southern Water's SINK score calculated?
Same ten questions for every company. No private weighting.
SINK = (0.3 × Base + 0.7 × Performance) × ScaleWhat evidence is Southern Water's score based on?
10 sources used in this assessment. All publicly available. Each row shows which of the ten questions it informed.
33% of them were published by Southern Water itself; the rest come from independent sources.
“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.”
If you believe a source has been misread or a newer version exists, submit a challenge.
Is this your company? Claim this profile (free)
Use this score in tenders
Send the link, or the one-page score sheet. It links back to this page and every source. Free.
Open the score sheet →Send new evidence, free
Scored low because little is published? Publish what you do and send us the link, free. If it holds up, your score changes, and the change is logged on your page.
How to send evidence →Put your score on your website, free
It shows the current band, sector rank and score, and links to this page, so it changes when the score does.
Track this score
Bidding for a public contract? Check if you need a Carbon Reduction Plan, free →
Want your own page like this?
Free, independent, every source shown. Send it to any buyer who asks about your sustainability.
How does Southern Water compare with other water & sewerage companies?
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.
Who scores higher in Water & Sewerage?
The 3 companies in the sector scoring nearest above Southern 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.
One email, every Sunday. Score changes, new research, the stories behind the numbers. Free.
We'll send one email to confirm. No spam. Unsubscribe in one click.
Checking a company?
Search free →Asked to prove you're sustainable?
Get your business scored, free →Been scored?
Find your page and claim it, free →Scores are free. Nobody can pay to change a score, speed it up or hide it.