Yorkshire Water storm overflows in 2025
What the official annual return shows for Yorkshire Water’s storm overflows in England, compared with 2024 and with the other water companies.
Summary
The 2025 annual return lists 2,187 storm overflows run by Yorkshire Water in England. 2,176 have a usable spill count. Together they recorded 51,431 spills and 285,931 hours of discharge. The median outlet recorded 16 spills and 37.8 hours.
For a fair comparison with 2024, we use only the 1,835 outlets with a count in both years and a monitor that worked at least 90% of each year. Their spills went from 61,624 to 45,371, a fall of 26%. 1,273 recorded fewer spills and 364 recorded more.
291 outlets (13.4%) recorded no spills in 2025. 206 (9.5%) recorded 60 or more.
Yorkshire Water’s median of 16 spills per outlet is the 2nd highest of the 10 companies in the return. The England median is 11.
203 outlets had a monitor that worked for less than 90% of the year, and 3 gave no operation figure. Counts from those outlets may be low.
- 2,187
- Outlets listed
- 51,431
- Spills in 2025
- 16
- Median per outlet
- 285,931
- 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
- 291 13.4%
- 1 to 9
- 569 26.1%
- 10 to 19
- 337 15.5%
- 20 to 39
- 507 23.3%
- 40 to 59
- 266 12.2%
- 60 or more
- 206 9.5%
Spills over time
The median outlet run by Yorkshire Water recorded 16 spills in 2025, against 11 across England.
1,835 outlets have a comparable count for both 2024 and 2025, with the monitor working at least 90% of each year. 364 recorded more spills, 1,273 fewer and 198 the same. Together they went from 61,624 to 45,371 spills, a fall of 26%.
Largest rises from 2024 to 2025
- Crow Nest Bridge/CSO0 → 91
- Flamborough Village/STW11 → 84
- Dunslow Road/CSO35 → 96
| Year | Outlets with a count | Total spills | Median per outlet | England median |
|---|---|---|---|---|
| 2025 | 2,176 | 51,431 | 16 | 11 |
| 2024 | 2,171 | 68,164 | 20 | 19 |
| 2023 | 2,156 | 77,628 | 23 | 20 |
| 2022 | 1,830 | 47,015 | 15 | 13 |
| 2021 | 1,598 | 50,687 | 19 | 19 |
| 2020 | 1,560 | 43,482 | 14 | 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.
- Langthorne/No 2 STW282 → 101
- Swinton Masham/No 2 STW229 → 62
- Thornton Le Dale/STW159 → 11
- Ruston Parva/STW186 → 53
- Navigation Road/CSO186 → 71
- Ampleforth Village/STW160 → 48
- Bishop Monkton/No 2 STW/3Xdwf Overflow138 → 26
- Millgate Masham/CSO139 → 30
- New Ellerby/STW149 → 41
- West Lilling/CSO174 → 66
Most spills in 2025
- 1Melton/STW245spills
River Humber
- 2Marske/STW170spills
Marske Beck
- 3Eastwood/STW129spills
River Calder
- 4Princess Bridge/No 2 CSO128spills
River Calder
- 5Ben Rhydding/STW127spills
River Wharfe
- 6Beamsley/STW120spills
River Wharfe
- 6Thornhills Beck Lane/CSO120spills
River Calder
- 8Bonegate Lane/CSO119spills
River Calder
- 9Leyburn/STW117spills
River Ure
- 9Thistle Street/CSO117spills
River Colne
Most hours in 2025
- 1Eastwood/STW2,182hours
River Calder
- 2Marske/STW2,046hours
Marske Beck
- 3City Square/CSO1,974hours
River Aire
- 4Harome/STW1,919hours
Harome Moor Drain
- 5Wistow/STW1,879hours
River Ouse (Tidal)
- 6Leyburn/STW1,771hours
River Ure
- 7Ben Rhydding/STW1,759hours
River Wharfe
- 8Langthorne/No 2 STW1,694hours
Cobshaw Dyke
- 9Woolworths/CSO1,682hours
River Ouse
- 10Fulford/No 2 SPS1,679hours
River Ouse
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 |
|---|---|---|---|
| Aire from Gill Beck (Baildon) to Wyke Beck | 85 | 2,032 | 23.9 |
| Ouse from River Nidd to Stillingfleet Beck | 41 | 1,405 | 34.3 |
| Calder from Ryburn Confluence to River Colne | 39 | 1,128 | 28.9 |
| Aire (R Worth to Gill Beck) | 40 | 1,077 | 26.9 |
| Calder from River Colne to River Chald | 41 | 998 | 24.3 |
| Don from Greasborough Dyke to River Dearne | 37 | 965 | 26.1 |
| Bradford Beck (Clayton Bk to R Aire) | 50 | 959 | 19.2 |
| River Colne from River Holme to River Calder | 33 | 819 | 24.8 |
| Meanwood Beck from Source to River Aire | 41 | 816 | 19.9 |
| Calder from Colden Water to Ryburn Confluence | 17 | 722 | 42.5 |
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