Polluted by sewage 1,538 hours in 2026 , monitoring offline 492 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 | Wingrave STW | Rowsham Brook | 46 | 680h 30m | 412 h |
| Anglian Water | MENTMORE STW | Un River Ouzel | 29 | 392h 32m | 48 h |
| Thames Water | Aylesbury STW | River Thame | 19 | 180h 45m | 24 h |
| Anglian Water | IVINGHOE STW | Whistle Brook, River Ouzel | 30 | 129h 31m | - |
| Anglian Water | NORTHALL SP | River Ouzel | 6 | 62h 43m | - |
| Anglian Water | IVINGHOE ASTON STW | Coombe Bottom Brook, R Ouzel | 15 | 44h 34m | - |
| Thames Water | Dagnall STW | Groundwater Via Infilt System | 9 | 26h 15m | 7 h |
| Thames Water | Marsworth SPS | Thame | 3 | 13h | - |
| Anglian Water | WING-CUBLINGTON ROAD STW | Wing Brook River Ouzel | 2 | 4h 39m | - |
| Thames Water | Rowsham STW | Rowsham Brook | 2 | 4h 15m | - |
| Thames Water | Wingrave STW | Rowsham Brook | 0 | 0h | - |
| Anglian Water | NORTHALL SP | River Ouzel | 0 | 0h | - |
| Thames Water | Marsworth SPS | Thame | 0 | 0h | - |
| Anglian Water | IVINGHOE ASTON STW | Coombe Bottom Brook, R Ouzel | 0 | 0h | - |
| Anglian Water | IVINGHOE STW | Whistle Brook, River Ouzel | 0 | 0h | - |
| Anglian Water | MENTMORE STW | Un River Ouzel | 0 | 0h | - |
| Thames Water | Aylesbury STW | River Thame | 0 | 0h | - |
| Anglian Water | WING-CUBLINGTON ROAD STW | Wing Brook River Ouzel | 0 | 0h | - |
| Thames Water | Rowsham STW | Rowsham Brook | 0 | 0h | - |
| Thames Water | Dagnall STW | Groundwater Via Infilt System | 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.