Polluted by sewage 5,947 hours in 2025
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 | Winterbourne STW | Winterbourne Stream | 116 | 2,635h | - |
| Thames Water | East Shefford STW | River Lambourn | 100 | 2,207h 15m | - |
| Thames Water | Hamstead Marshall STW | Hamstead Stream | 19 | 374h 30m | - |
| Thames Water | Newbury STW | Kennet | 21 | 332h 13m | - |
| Thames Water | Hamstead Marshall STW | Hamstead Stream | 17 | 186h 45m | - |
| Thames Water | Kintbury STW | Kennet | 10 | 128h 10m | - |
| Thames Water | Newbury STW | Kennet | 4 | 51h 30m | - |
| Thames Water | Kintbury STW | Kennet | 2 | 31h 44m | - |
| Thames Water | East Shefford STW | River Lambourn | 0 | 0h | - |
| Thames Water | Winterbourne STW | Winterbourne Stream | 0 | 0h | - |
| Thames Water | East Garston SPS | River Lambourn | 0 | 0h | - |
| Thames Water | East Garston SPS | River Lambourn | 0 | 0h | - |
| Thames Water | Chieveley STW | Winterbourne Stream | 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.