Wessex Water, which supplies most of Dorset, is rated 'requires improvement' for 2025, with 164 sewage pollution incidents against a target of 68.
Wessex Water has been rated two stars out of four by the Environment Agency for the second year running. The rating means “company requires improvement”. It was published on Thursday 29 October in the agency’s annual report on the nine water and sewerage companies in England.
Wessex Water supplies most of the Dorset Council area, including Dorchester, Weymouth, Bridport, Sherborne and Blandford. The figures below cover its whole region, not Dorset alone. The agency does not break them down by county.
Where it fell short
The rating is built from six measures. In 2025 Wessex Water was rated red on two, amber on one and green on three, according to its company data report.
| Measure | 2025 result | Rating |
|---|---|---|
| Sewage pollution incidents | 164, or 47 per 10,000km of sewer (green needed 68 or fewer) | Red |
| Serious pollution incidents | 4, all from sewerage (green needed none) | Red |
| Treatment works meeting permit limits | 98.7% | Amber |
| Pollution incidents it reported itself | 93% | Green |
| Environmental schemes delivered on time | 100% (13 of 13) | Green |
| Sludge disposal | 100% satisfactory | Green |
Its rate of 47 sewage pollution incidents per 10,000km of sewer was worse than the sector average of 41.
The number of incidents fell from 215 in 2024 to 164 in 2025. That is still roughly double the level of 2016 to 2021, when it ran between 72 and 87 a year.
Where the incidents came from
The report breaks down the 164 sewerage incidents by source:
- pumping stations: 74
- foul sewers: 49
- sewage treatment works: 22
- rising mains, the pipes that pump sewage uphill: 17
- storm overflows: 2
Of the four serious incidents, three came from foul sewers and one from a sewage treatment works.
Storm overflows
Every one of Wessex Water’s 1,346 storm overflows has a monitor. In 2025 the monitored overflows spilled an average of 18.3 times each, and each spill lasted 7.8 hours on average, the report says.
Once industry leading
Wessex Water was rated four stars, the top grade, in eight of the 15 years since the assessment began in 2011, most recently in 2023. It has been two stars in 2021, 2022, 2024 and 2025, according to the agency’s star ratings table.
Across England the picture is worse. The national report gives:
- 4 stars: Severn Trent Water only
- 2 stars: Anglian Water, Northumbrian Water, United Utilities and Wessex Water
- 1 star: Southern Water, South West Water, Thames Water and Yorkshire Water
South West Water, which now includes Bournemouth Water, is one of the four rated poor. The sector scored 16 stars out of a possible 36, its lowest total since the assessment began.
What it means for you
- If you see sewage in a river, on a beach or coming from a manhole, report it to the Environment Agency’s 24-hour incident line on 0800 80 70 60. Reports from the public count: 16 of Wessex Water’s incidents in 2025 were reported by others rather than by the company.
- The figures cover the whole company, so they do not show which Dorset rivers or beaches were affected. Our Dorset hosepipe ban page sets out which company supplies which part of the county.
Have your say