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Polluted by sewage 3,031 hours in 2025
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We get information about overflowing CSOs since January 2025. Here is a chart of the last three months of data for Dorking and Horley, here you can see overflows in red, the darker the red, the more the CSO overflowed that day.
Each CSO has a row, the most recent data is on the right hand side.
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Donate Now| Company | Site Name | Receiving Waterway | Overflow Days | Total Duration (hours) | Total Duration (days) |
|---|---|---|---|---|---|
| Thames Water | Holmwood STW | Holmwood Stream | 40 | 524 h | 21.83 |
| Thames Water | Horley (Surrey) STW | Mole | 35 | 500 h 15m | 20.83 |
| Thames Water | Holmwood STW | Holmwood Stream | 17 | 295 h 15m | 12.29 |
| Thames Water | Dorking STW | River Mole | 20 | 257 h 45m | 10.71 |
| Thames Water | Stonebridge sso, brockham | River Mole | 23 | 250 h | 10.42 |
| Thames Water | Ironsbottom STW | River Mole | 21 | 229 h | 9.54 |
| Thames Water | Horley (Surrey) STW | Mole | 18 | 226 h 45m | 9.42 |
| Thames Water | Ironsbottom STW | River Mole | 13 | 116 h 15m | 4.83 |
| Thames Water | Charlwood, surrey | Mans Brook | 17 | 114 h | 4.75 |
| Thames Water | Canfold Wood (Ewhurst) SPS | Thornhurst Brook | 12 | 73 h 45m | 3.04 |
| Thames Water | Capel SPS | Deanoak Brook | 9 | 49 h 45m | 2.04 |
| Thames Water | Ockley Road (Ewhurst) SPS | Cobbler'S Brook | 5 | 49 h 15m | 2.04 |
| Thames Water | Brockham Bridge XX SPS | River Mole | 5 | 48 h 30m | 2 |
| Thames Water | Dorking STW | River Mole | 3 | 45 h 45m | 1.88 |
| Thames Water | Charlwood, surrey | Mans Brook | 4 | 37 h 15m | 1.54 |
| Thames Water | Castle Gardens (Dorking) SPS | Mole | 7 | 36 h 15m | 1.5 |
| Thames Water | Salfords SPS | Salfords Stream | 6 | 24 h 30m | 1 |
| Thames Water | Brockham Bridge XX SPS | River Mole | 2 | 23 h | 0.96 |
| Thames Water | Spooks hill, north holmwood | Tanners Brook | 8 | 22 h | 0.92 |
| Thames Water | Stonebridge sso, brockham | River Mole | 3 | 21 h 45m | 0.88 |
| Thames Water | Canfold Wood (Ewhurst) SPS | Thornhurst Brook | 3 | 15 h 45m | 0.62 |
| Thames Water | Commonside (Leatherhead) SPS | Bookham Brook | 7 | 12 h | 0.5 |
| Thames Water | Boxhill SPS | Into Land | 9 | 11 h 15m | 0.46 |
| Thames Water | Boxhill SPS | Into Land | 3 | 10 h | 0.42 |
| Thames Water | Capel SPS | Deanoak Brook | 3 | 9 h 45m | 0.38 |
| Thames Water | Ockley Road (Ewhurst) SPS | Cobbler'S Brook | 1 | 6 h | 0.25 |
| Thames Water | Spooks hill, north holmwood | Tanners Brook | 1 | 5 h 45m | 0.21 |
| Thames Water | Castle Gardens (Dorking) SPS | Mole | 1 | 5 h 45m | 0.21 |
| Thames Water | Salfords SPS | Salfords Stream | 1 | 5 h | 0.21 |
| Thames Water | River Lane (Leatherhead) SPS | Mole | 3 | 5 h | 0.21 |
| Thames Water | River Lane (Leatherhead) SPS | Mole | 0 | 0 h | 0 |
| Thames Water | Dean Oak Lane (Leigh) SPS | Deanoak Brook | 0 | 0 h | 0 |
| Thames Water | Commonside (Leatherhead) SPS | Bookham Brook | 0 | 0 h | 0 |
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.
Get in touch if you have queries or want to discuss our data.
press [at] top-of-the-poops.org