Media Queries
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Polluted by sewage 4,013 hours in 2025 , monitoring offline 721 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 |
|---|---|---|---|---|---|
| Thames Water | Compton STW | River Pang | 79 | 1,332h 30m | - |
| Thames Water | Hampstead Norreys STW | River Pang | 33 | 628h 30m | - |
| Thames Water | Burghfield STW | Clay Hill Brook | 31 | 594h 45m | - |
| Thames Water | Pangbourne STW | River Sul | 14 | 271h | - |
| Thames Water | Aldermaston STW | Groundwater Via Land Treatment | 25 | 211h 45m | - |
| Thames Water | Chapel Row STW | River Bourne | 15 | 185h 15m | 434 h |
| Thames Water | Mortimer STW | Foudry Brook | 11 | 181h 45m | 286 h |
| Thames Water | Briff Lane (Bucklebury) STW | Briff Lane Stream | 18 | 175h 15m | - |
| Thames Water | Mortimer STW | Foudry Brook | 8 | 130h 30m | - |
| Thames Water | Beenham STW | Webbs Lane Stream | 14 | 130h 15m | - |
| Thames Water | Burghfield STW | Clay Hill Brook | 4 | 59h 30m | - |
| Thames Water | Briff Lane (Bucklebury) STW | Briff Lane Stream | 4 | 42h 45m | - |
| Thames Water | Chapel Row STW | River Bourne | 3 | 37h 30m | - |
| Thames Water | Aldermaston STW | Groundwater Via Land Treatment | 3 | 25h 30m | - |
| Thames Water | Midgham STW | Kennet | 1 | 6h 15m | - |
| Thames Water | Pangbourne STW | River Sul | 0 | 0h | - |
| Thames Water | Midgham STW | Kennet | 0 | 0h | - |
| Thames Water | Beenham STW | Webbs Lane Stream | 0 | 0h | - |
| Thames Water | Compton STW | River Pang | 0 | 0h | - |
| Thames Water | Hampstead Norreys STW | River Pang | 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