Polluted by sewage 1,089 hours in 2025 , monitoring offline 2,062 hours , potential overflows 292 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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| Company | Site Name | Receiving Waterway | Overflow Days | Total Duration (hours) | Offline/Potential Pollution |
|---|---|---|---|---|---|
| United Utilities | LIVERPOOL WwTW | River Mersey Estuary | 89 | 474 h 5m | 249 h |
| United Utilities | LIVERPOOL WwTW | River Mersey Estuary | 48 | 324 h 40m | 91 h |
| United Utilities | LIVERPOOL WwTW | River Mersey Estuary | 17 | 114 h 37m | 2 h |
| United Utilities | LIVERPOOL WwTW | River Mersey Estuary | 19 | 112 h 57m | 5 h |
| United Utilities | Northern CSO | River Mersey Estuarine Waters | 19 | 38 h 24m | 58 h |
| United Utilities | Bankhall Relief CSO | River Mersey | 9 | 10 h 11m | 55 h |
| United Utilities | Beacons Gutter CSO | River Mersey Estuary | 8 | 4 h 36m | 267 h |
| United Utilities | St. Nicholas Storm Sewer overflow | Mill Dam | 5 | 3 h 18m | 10 h |
| United Utilities | Sandhills Lane CSO | Mersey Estuary | 2 | 1 h 56m | 286 h |
| United Utilities | Gower Street/Kings Dock CSO | River Douglas | 2 | 1 h 30m | 650 h |
| United Utilities | Battery Lane CSO | Mersey Estuary | 3 | 1 h 6m | 403 h |
| United Utilities | Bankhall CSO | River Mersey | 4 | 0 h 45m | 241 h |
| United Utilities | Park Street SO | River Mersey Estuary | 1 | 0 h 19m | 31 h |
| United Utilities | Beacons Gutter CSO | River Mersey Estuary | 1 | 0 h 18m | - |
| United Utilities | Battery Lane CSO | Mersey Estuary | 1 | 0 h 17m | - |
| United Utilities | St. Nicholas Storm Sewer overflow | Mill Dam | 1 | 0 h 15m | - |
| United Utilities | Gower Street/Kings Dock CSO | River Douglas | 1 | 0 h 10m | - |
| United Utilities | Northern CSO | River Mersey Estuarine Waters | 1 | 0 h 6m | - |
| United Utilities | Park Street SO | River Mersey Estuary | 1 | 0 h | - |
| United Utilities | Bankhall Relief CSO | River Mersey | 0 | 0 h | - |
| United Utilities | Bankhall CSO | River Mersey | 0 | 0 h | - |
| United Utilities | Sandhills Lane CSO | Mersey Estuary | 0 | 0 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
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.