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Polluted by sewage 6,234 hours in 2026 , monitoring offline 77 hours so far..
What's a potential overflow? If the CSO goes 'Offline' while its Overflowing, we don't know if it stopped overflowing until we get a 'Stop' event.
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Donate Now| Company | Site Name | Receiving Waterway | Overflow Days | Total Duration (hours) | Offline/Potential Pollution |
|---|---|---|---|---|---|
| Thames Water | Princes Risborough STW | Horsenden Stream | 53 | 1,077h 45m | - |
| Thames Water | Stone STW | Scotsgrove Brook | 47 | 1,049h 30m | - |
| Thames Water | Haddenham STW | Scotsgrove Brook | 47 | 1,035h 30m | - |
| Thames Water | Ludgershall STW | Ludgershall Brook | 50 | 862h 15m | - |
| Thames Water | Cuddington STW | River Thame | 27 | 472h 15m | 17 h |
| Thames Water | Waddesdon STW | Fleet Marston Brook | 31 | 427h 30m | 12 h |
| Thames Water | Marsh Gibbon STW | Summerstown Ditch | 35 | 387h 45m | - |
| Thames Water | Grendon Underwood STW | Oxon Ray | 37 | 361h 15m | 30 h |
| Thames Water | Shabbington STW | Shabbington Brook | 24 | 315h | - |
| Anglian Water | TWYFORD-SCHOOL LANE TPS | Padbury Brook | 7 | 167h 45m | - |
| Thames Water | Worminghall STW | Worminghallbrook | 19 | 72h 30m | 0 h |
| Thames Water | Dorton STW | Dorton Brook | 9 | 5h 30m | 17 h |
| Thames Water | Worminghall STW | Worminghallbrook | 0 | 0h | - |
| Thames Water | Grendon Underwood STW | Oxon Ray | 0 | 0h | - |
| Thames Water | Cuddington STW | River Thame | 0 | 0h | - |
| Anglian Water | POUNDON STW | Poundon Brook | 0 | 0h | - |
| Thames Water | Long Crendon STW | Crendon Stream | 0 | 0h | - |
| Anglian Water | POUNDON STW | Poundon Brook | 0 | 0h | - |
| Thames Water | Shabbington STW | Shabbington Brook | 0 | 0h | - |
| Anglian Water | TWYFORD-SCHOOL LANE TPS | Padbury Brook | 0 | 0h | - |
| Thames Water | Marsh Gibbon STW | Summerstown Ditch | 0 | 0h | - |
| Thames Water | Dorton STW | Dorton Brook | 0 | 0h | - |
| Thames Water | Haddenham STW | Scotsgrove Brook | 0 | 0h | - |
| Thames Water | Waddesdon STW | Fleet Marston Brook | 0 | 0h | - |
| Thames Water | Princes Risborough STW | Horsenden Stream | 0 | 0h | - |
| Thames Water | Ludgershall STW | Ludgershall Brook | 0 | 0h | - |
| Thames Water | Stone STW | Scotsgrove Brook | 0 | 0h | - |
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
Annual figures up to and including 2025 come from official water company returns. The 2026 figure is our own estimate, derived continuously from the companies' live data feeds.
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.
Get in touch if you have queries or want to discuss our data.
press [at] top-of-the-poops.org