Media Queries
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Polluted by sewage 2,326 hours in 2025 , monitoring offline 2,064 hours , potential overflows 336 hours
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 | ASHBROOK STW | Ash Brook, River Great Ouse | 28 | 564h 27m | - |
| Anglian Water | CLIFTON STW | Henlow Brook | 28 | 528h 31m | - |
| Anglian Water | HITCHIN STW | River Hiz | 29 | 523h 33m | - |
| Anglian Water | HITCHIN STW | River Hiz | 23 | 514h 59m | - |
| Thames Water | Whitwell STW | River Mimram | 13 | 92h 45m | 750 h |
| Anglian Water | CLIFTON STW | Henlow Brook | 3 | 40h 48m | - |
| Anglian Water | HITCHIN STW | River Hiz | 2 | 13h 43m | - |
| Anglian Water | ASHBROOK STW | Ash Brook, River Great Ouse | 3 | 12h 45m | 336 h |
| Anglian Water | STOTFOLD-BROOK END SP | Tingewick Brook | 1 | 9h 45m | - |
| Anglian Water | POPPYHILL STW | River Ivel | 3 | 9h 26m | 1,314 h |
| Anglian Water | POPPYHILL STW | River Ivel | 1 | 6h 14m | - |
| Anglian Water | HITCHIN STW | River Hiz | 4 | 5h 5m | - |
| Anglian Water | STOTFOLD-BROOK END SP | Tingewick Brook | 2 | 1h 54m | - |
| Anglian Water | HITCHIN - GOSMORE SP | Purwell | 1 | 1h 21m | - |
| Anglian Water | PIRTON TPS | River Hiz | 1 | 1h 15m | - |
| Anglian Water | POPPYHILL STW | River Ivel | 0 | 0h | - |
| Thames Water | Whitwell STW | River Mimram | 0 | 0h | - |
| Anglian Water | PIRTON TPS | River Hiz | 0 | 0h | - |
| Anglian Water | POPPYHILL STW | River Ivel | 0 | 0h | - |
| Anglian Water | HITCHIN-BANCROFT REC SSO | 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