Polluted by sewage 4,556 hours in 2026 , monitoring offline 769 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 | Little Milton STW | Gainsbridge Brook | 55 | 1,188h 45m | - |
| Thames Water | Thame STW | Lashlake Stream | 49 | 913h 45m | - |
| Thames Water | Chinnor STW | Henton Stream | 52 | 802h 32m | - |
| Thames Water | Benson STW | Howbery Ditch | 30 | 660h 50m | - |
| Thames Water | Wheatley STW | Wheatley Ditch | 47 | 447h 15m | - |
| Thames Water | Watlington STW | Pyrton Stream | 48 | 445h 45m | - |
| Thames Water | Chalgrove STW | Warpsgrave Ditch | 10 | 51h 15m | - |
| Thames Water | Manor Farm Road (Sydenham) SPS | Sydenham Stream | 3 | 18h 15m | 59 h |
| Thames Water | Beckley STW | Otmoor Lane Ditch | 2 | 13h 30m | - |
| Thames Water | Tetsworth STW | Latchford Brook | 9 | 11h 30m | - |
| Thames Water | Forest Hill STW | Polecat End Ditch | 2 | 2h | - |
| Thames Water | Friday Street (Henley) SPS | Thames | 2 | 1h 22m | 386 h |
| Thames Water | Sonning Common STW | Into Land | 0 | 0h | - |
| Thames Water | Thame STW | Lashlake Stream | 0 | 0h | - |
| Thames Water | Caversham (Reading) SPS | Thames | 0 | 0h | 323 h |
| Thames Water | Tetsworth STW | Latchford Brook | 0 | 0h | - |
| Thames Water | Benson STW | Howbery Ditch | 0 | 0h | - |
| Thames Water | Friday Street (Henley) SPS | Thames | 0 | 0h | - |
| Thames Water | Little Milton STW | Gainsbridge Brook | 0 | 0h | - |
| Thames Water | Dorchester STW | Thame | 0 | 0h | - |
| Thames Water | Wheatley STW | Wheatley Ditch | 0 | 0h | - |
| Thames Water | Chinnor STW | Henton Stream | 0 | 0h | - |
| Thames Water | Watlington STW | Pyrton Stream | 0 | 0h | - |
| Thames Water | Forest Hill STW | Polecat End Ditch | 0 | 0h | - |
| Thames Water | Chalgrove STW | Warpsgrave Ditch | 0 | 0h | - |
| Thames Water | Dorchester STW | Thame | 0 | 0h | - |
| Thames Water | Caversham (Reading) SPS | Thames | 0 | 0h | - |
| Thames Water | Sonning Common STW | Into Land | 0 | 0h | - |
| Thames Water | Beckley STW | Otmoor Lane Ditch | 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.