Polluted by sewage 1,029 hours in 2025 , monitoring offline 1,461 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 | Haslemere STW | River Wey | 24 | 230h | - |
| Thames Water | Farnham STW | Farnham Park | 17 | 200h 15m | - |
| Southern Water | GRAYSWOOD CSO - 115984 | Two S Of River Chidd | 24 | 197h | - |
| Southern Water | GRAYSWOOD CSO - 115984 | Two S Of River Chidd | 12 | 86h 33m | - |
| Thames Water | Bordon STW | Wey | 5 | 84h 45m | - |
| Thames Water | Haslemere STW | River Wey | 10 | 72h 45m | - |
| Thames Water | Farnham STW | Farnham Park | 6 | 61h 30m | - |
| Thames Water | Haslemere STW CSO | River Wey | 5 | 40h 44m | - |
| Thames Water | Waverley Lane (Farnham) SPS | Farnham Bourne | 4 | 22h 30m | 186 h |
| Thames Water | Bordon STW | Wey | 2 | 13h 30m | - |
| Thames Water | Waverley Lane (Farnham) SPS | Farnham Bourne | 2 | 10h | - |
| Thames Water | Churt SPS | Whitmoor Vale Stream | 1 | 5h 18m | - |
| Thames Water | Churt SPS | Whitmoor Vale Stream | 4 | 3h 4m | 388 h |
| Thames Water | Haslemere STW CSO | River Wey | 1 | 1h 8m | 61 h |
| Thames Water | Arford SPS | River Wey | 0 | 0h | 456 h |
| Thames Water | Arford SPS | River Wey | 0 | 0h | - |
| Thames Water | Passfield (Bramshott) SPS | River Wey | 0 | 0h | - |
| Thames Water | Passfield (Bramshott) SPS | River Wey | 0 | 0h | 367 h |
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.