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Polluted by sewage 60 hours in 2026 , monitoring offline 51 hours so far..
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Donate Now| Company | Site Name | Receiving Waterway | Overflow Days | Total Duration (hours) | Offline/Potential Pollution |
|---|---|---|---|---|---|
| Thames Water | Dagnall STW | Groundwater Via Infilt System | 9 | 26h 15m | 7 h |
| Thames Water | Watery Lane (Marsworth) SPS | Tring Bourne | 12 | 19h 15m | 12 h |
| Thames Water | Berkhamsted STW | Grand Union Canal | 3 | 12h 15m | 15 h |
| Thames Water | Hambleden STW | River Thames | 2 | 2h | - |
| Thames Water | Sonning Common STW | Into Land | 1 | 0h 30m | - |
| Thames Water | Tring STW | Into Guc/Reservoir | 1 | 0h 30m | - |
| Thames Water | Chesham STW | River Chess | 0 | 0h | 17 h |
| Thames Water | Amersham balancing tanks/amersham vale stk | Misbourne | 0 | 0h | - |
| Thames Water | Dagnall STW | Groundwater Via Infilt System | 0 | 0h | - |
| Thames Water | Goring STW | River Thames | 0 | 0h | - |
| Thames Water | Sonning Common STW | Into Land | 0 | 0h | - |
| Thames Water | Hambleden STW | River Thames | 0 | 0h | - |
| Thames Water | Chesham STW | River Chess | 0 | 0h | - |
| Thames Water | Henley STW | Fawley Court Stream | 0 | 0h | - |
| Thames Water | Amersham balancing tanks/amersham vale stk | Misbourne | 0 | 0h | - |
| Thames Water | Berkhamsted STW | Grand Union Canal | 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