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Polluted by sewage 121 hours in 2026 , monitoring offline 17 hours , potential overflows 890 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 |
|---|---|---|---|---|---|
| Anglian Water | HITCHIN STW | River Hiz | 5 | 52h 26m | - |
| Anglian Water | ASHBROOK STW | Ash Brook, River Great Ouse | 4 | 16h 1m | 890 h |
| Anglian Water | CLIFTON STW | Henlow Brook | 2 | 14h 23m | - |
| Thames Water | Whitwell STW | River Mimram | 3 | 12h 45m | 17 h |
| Anglian Water | STOTFOLD-BROOK END SP | Tingewick Brook | 5 | 8h 44m | - |
| Anglian Water | HITCHIN STW | River Hiz | 6 | 7h 31m | - |
| Anglian Water | POPPYHILL STW | River Ivel | 2 | 4h 16m | - |
| Anglian Water | HITCHIN - GOSMORE SP | Purwell | 2 | 3h | - |
| Anglian Water | PIRTON TPS | River Hiz | 1 | 1h 14m | - |
| Anglian Water | HITCHIN-BANCROFT REC SSO | River Hiz | 1 | 0h 59m | - |
| Anglian Water | ASHBROOK STW | Ash Brook, River Great Ouse | 0 | 0h | - |
| Anglian Water | POPPYHILL STW | River Ivel | 0 | 0h | - |
| Anglian Water | PIRTON TPS | River Hiz | 0 | 0h | - |
| Thames Water | Whitwell STW | River Mimram | 0 | 0h | - |
| Anglian Water | CLIFTON STW | Henlow Brook | 0 | 0h | - |
| Anglian Water | POPPYHILL STW | River Ivel | 0 | 0h | - |
| Anglian Water | HITCHIN STW | River Hiz | 0 | 0h | - |
| Anglian Water | STOTFOLD-BROOK END SP | Tingewick Brook | 0 | 0h | - |
| Anglian Water | POPPYHILL STW | River Ivel | 0 | 0h | - |
| Anglian Water | HITCHIN STW | River Hiz | 0 | 0h | - |
| Anglian Water | HITCHIN - GOSMORE SP | Purwell | 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