Here are the top rivers in England and Wales that had sewage overflows in 2025. As the list is grouped by company, some rivers may feature more than once, being polluted by different companies along their length.
The full list is quite long. You can access that
As there are different rivers with the same name in different parts of the country, it didn't seem sensible to group by river name alone.
The category of "river" is made by the water companies in their "Consent to Discharge with Conditions" - so although there are a number of Seas in this list, that's what they are reporting
| Rank | River | Company | Sewage Dumps | Change | Duration (Hours) | Change |
| 1 | River Teifi | Dwr Cymru Welsh Water | 2,494 | 262 | 27,661 | 5,372 |
| 2 | Unknown | South West Water | 3,803 | 990 | 25,408 | -4,809 |
| 3 | River Ouse | Yorkshire Water | 3,779 | 1,280 | 18,499 | -7,050 |
| 4 | River Calder | Yorkshire Water | 2,978 | -395 | 18,184 | -1,340 |
| 5 | River Aire | Yorkshire Water | 3,112 | -885 | 17,636 | -3,555 |
| 6 | River Avon | Wessex Water | 2,650 | -2,571 | 14,496 | -24,569 |
| 7 | River Tamar | South West Water | 1,460 | -541 | 13,790 | -7,447 |
| 8 | River Tawe | Dwr Cymru Welsh Water | 1,696 | -477 | 11,834 | -4,309 |
| 9 | River Derwent | Severn Trent Water | 1,971 | -704 | 10,811 | -4,917 |
| 10 | River Taff | Dwr Cymru Welsh Water | 1,279 | -170 | 10,229 | -1,903 |
| 11 | River Don | Yorkshire Water | 2,489 | 660 | 10,162 | -1,834 |
| 12 | River Wharfe | Yorkshire Water | 1,476 | -468 | 9,899 | -4,900 |
| 13 | Gwendraeth Fawr | Dwr Cymru Welsh Water | 1,148 | 119 | 9,820 | 2,443 |
| 14 | River Trent | Severn Trent Water | 1,952 | -1,234 | 9,628 | -16,455 |
| 15 | River Usk | Dwr Cymru Welsh Water | 1,313 | -448 | 9,285 | -5,458 |
| 16 | River Marlais | Dwr Cymru Welsh Water | 575 | -62 | 9,239 | -490 |
| 17 | River Irwell | United Utilities | 1,885 | -638 | 9,208 | -2,737 |
| 18 | River Derwent | United Utilities | 1,016 | -50 | 9,190 | -415 |
| 19 | River Rhymney | Dwr Cymru Welsh Water | 1,505 | -443 | 8,915 | -2,091 |
| 20 | River Gwili | Dwr Cymru Welsh Water | 1,017 | -60 | 8,854 | -587 |
EDM (Event Duration Monitoring) data and Consented Discharges to Controlled Waters with Conditions from Environment Agency & Data Map Wales, and Scottish Water
Experimental derived data from Thames Water API, Some data may be missing or inaccurate. Live sewage data from Stream Water API
Uses Environment Agency rainfall data from the real-time data API (Beta) - Rainfall data is delayed by up to two days.
This website is intended to provide an accurate representation of the Environment Agency data. The data is hard to use, and thus some errors may have been made. If you find something that is incorrect, please raise an issue at the GitHub issues page and we'll endeavour to fix it quickly.
This project is not associated, approved or endorsed by any of the companies whose logos you see here.