Severn Trent Water storm overflows in 2025
What the official annual return shows for Severn Trent Water’s storm overflows in England, compared with 2024 and with the other water companies.
Summary
The 2025 annual return lists 2,452 storm overflows run by Severn Trent Water in England. 2,431 have a usable spill count. Together they recorded 36,471 spills and 200,361 hours of discharge. The median outlet recorded 8 spills and 16.2 hours.
For a fair comparison with 2024, we use only the 2,154 outlets with a count in both years and a monitor that worked at least 90% of each year. Their spills went from 54,191 to 31,989, a fall of 41%. 1,415 recorded fewer spills and 415 recorded more.
429 outlets (17.6%) recorded no spills in 2025. 76 (3.1%) recorded 60 or more.
Severn Trent Water’s median of 8 spills per outlet is the 7th highest of the 10 companies in the return. The England median is 11.
90 outlets had a monitor that worked for less than 90% of the year, and 20 gave no operation figure. Counts from those outlets may be low.
- 2,452
- Outlets listed
- 36,471
- Spills in 2025
- 8
- Median per outlet
- 200,361
- Recorded hours
How many spills each outlet recorded
Outlets with a usable 2025 count, grouped by the number of spills. The longest bar is the largest group.
- 0
- 429 17.6%
- 1 to 9
- 862 35.5%
- 10 to 19
- 464 19.1%
- 20 to 39
- 427 17.6%
- 40 to 59
- 173 7.1%
- 60 or more
- 76 3.1%
Spills over time
The median outlet run by Severn Trent Water recorded 8 spills in 2025, against 11 across England.
2,154 outlets have a comparable count for both 2024 and 2025, with the monitor working at least 90% of each year. 415 recorded more spills, 1,415 fewer and 324 the same. Together they went from 54,191 to 31,989 spills, a fall of 41%.
Largest rises from 2024 to 2025
| Year | Outlets with a count | Total spills | Median per outlet | England median |
|---|---|---|---|---|
| 2025 | 2,431 | 36,471 | 8 | 11 |
| 2024 | 2,438 | 61,933 | 13.5 | 19 |
| 2023 | 706 | 29,861 | 31 | 20 |
| 2022 | 709 | 20,634 | 21 | 13 |
| 2021 | 679 | 29,846 | 31 | 19 |
| 2020 | 673 | 29,114 | 24 | 18 |
Earlier returns list fewer of these outlets, so totals are not comparable between years. The median per outlet and the like-for-like change are fairer comparisons. Counts are events, not volume.
Largest falls from 2024 to 2025
Only outlets with a count in both years and at least 90% monitor operation in each. Counts depend on rainfall as well as on the sewer network, so a fall does not show on its own that an overflow improved.
- Lower Moor STW (CSO)225 → 18
- Crowle - Scunthorpe STW (SSTO)216 → 51
- Ackleton - Stableford STW (SSTO)180 → 18
- Wellesbourne STW 3Dwf (SSTO)224 → 87
- Frankton STW (SSTO)217 → 83
- Pitts Mill STW (SSTO)179 → 51
- Barton STW (SSTO)155 → 33
- Northend STW (CSO)203 → 84
- Wem - Aston Road STW (SSTO)131 → 13
- Wyaston STW (CSO)116 → 0
Most spills in 2025
- 1Lydney STW (SSTO)178spills
River Severn Estuary · monitor 89.7%
- 2Church Stretton STW (SSTO)162spills
Tributary of Quinny Brook
- 3Blakeney (STW)153spills
River Severn
- 4Warslow STW (SSTO)152spills
Warslow Brook
- 5Prees - Mill Street (CSO)151spills
Tributary of Sidleymoor Brook
- 6Bradwell - The Crescent 23 (CSO)127spills
Bradwell Brook
- 7Sutton On Trent - Cromwell STW (SSTO)125spills
River Trent
- 8Snarestone STW (SSTO)121spills
River Mease
- 9Matlk Bth-Dale Rd (Coal Merchants) (CSO)118spills
River Derwent
- 10Tetbury - Avening STW (CSO)113spills
Nailsworth Stream
Most hours in 2025
- 1Church Stretton STW (SSTO)3,257hours
Tributary of Quinny Brook
- 2Warslow STW (SSTO)2,007hours
Warslow Brook
- 3Snarestone STW (SSTO)1,969hours
River Mease
- 4Sutton On Trent - Cromwell STW (SSTO)1,601hours
River Trent
- 5Blakeney (STW)1,579hours
River Severn
- 6Wellesbourne STW 3Dwf (SSTO)1,509hours
River Dene
- 7Lydney STW (SSTO)1,476hours
River Severn Estuary · monitor 89.7%
- 8Bradwell - The Crescent 23 (CSO)1,394hours
Bradwell Brook
- 9Matlock Lea STW (SSTO)1,282hours
River Derwent
- 10Froghall STW (SSTO)1,252hours
River Churnet
Waterbodies with the most spills
Total 2025 spills from outlets the return links to each waterbody. A waterbody with more outlets will usually have a higher total.
| Waterbody | Outlets | Spills | Spills per outlet |
|---|---|---|---|
| Derwent from Wye to Amber | 33 | 1,038 | 31.5 |
| Trent from Soar to The Beck | 38 | 942 | 24.8 |
| Amber from Alfreton Brook to Derwent | 27 | 646 | 23.9 |
| Severn - conf Bele Bk to conf Sundorne Bk | 35 | 615 | 17.6 |
| Derwent from Bottle Brook to Trent | 30 | 599 | 20 |
| Derwent from Amber to Bottle Brook | 33 | 475 | 14.4 |
| Severn River and Trib Estuary | 15 | 466 | 31.1 |
| Tame - conf two arms to R Rea | 45 | 434 | 9.6 |
| Erewash from Source to Nethergreen Brook | 22 | 431 | 19.6 |
| Erewash from Gilt Brook to Trent | 27 | 397 | 14.7 |
How to read this report
- A spill is a counted event under the 12/24-hour method. It is not a volume, and it does not measure harm or water quality.
- Missing counts are left out, not treated as zero. Low monitor operation can make a count too low.
- Rankings compare counts only. They do not show whether an overflow broke its permit or the law.
- Earlier years list fewer outlets, so compare medians or like-for-like groups, not totals.
Data: Environment Agency event duration monitoring annual returns, Open Government Licence v3.0. How spills are counted · How the data works · Sources