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Dorking and Horley - 2025 Sewage

Polluted by sewage 3,021 hours in 2025 , monitoring offline 4,508 hours , potential overflows 2,841 hours

© OpenStreetMap contributors
Contains OS Data © Crown copyright & database right 2021-2024
© Top of the Poops 2021-2024

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View Annual Sewage Data

You're looking at the totals that we have calculated for sewage in Dorking and Horley for 2025. It is an estimate, based on very poor quality live data from the Water Companies. This may not align with the 'official' reported sewage values from the water companies, which is reported in April following then end of the year - so 2025 numbers are reported in April 2026.

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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Constituencies near Dorking and Horley

Daily Data

Jan - 1,145 hours , 800 offline
Feb - 634 hours , 58 offline
Mar - 29 hours , 304 offline
Apr - 4 hours , 273 offline
May - 61 hours , 121 potential
Jun - 16 hours , 367 potential
Jul - 47 hours , 585 offline
Aug - 15 hours , 640 potential
Sept - 40 hours , 720 potential
Oct - 145 hours , 744 potential
Nov - 137 hours , 248 potential
Dec - 744 hours
Daily data is experimental and data is not guaranteed to be accurate. Please inform us of any issue, we will fix.
Please note: We don't have rainfall data for Wales. If you know where to source it please let us know!
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Totals so far

Company Site Name Receiving Waterway Overflow Days Total Duration (hours) Offline/Potential Pollution
Thames Water Holmwood STW Holmwood Stream 40 524 h -
Thames Water Horley (Surrey) STW Mole 35 500 h 15m 2,353 h
Thames Water Holmwood STW Holmwood Stream 17 295 h 15m -
Thames Water Dorking STW River Mole 20 257 h 45m -
Thames Water Stonebridge sso, brockham River Mole 22 240 h 488 h
Thames Water Ironsbottom STW River Mole 21 229 h 1,256 h
Thames Water Horley (Surrey) STW Mole 18 226 h 45m -
Thames Water Ironsbottom STW River Mole 13 116 h 15m -
Thames Water Charlwood, surrey Mans Brook 17 114 h 265 h
Thames Water Canfold Wood (Ewhurst) SPS Thornhurst Brook 12 73 h 45m -
Thames Water Capel SPS Deanoak Brook 9 49 h 45m -
Thames Water Ockley Road (Ewhurst) SPS Cobbler'S Brook 5 49 h 15m 2,075 h
Thames Water Brockham Bridge XX SPS River Mole 5 48 h 30m -
Thames Water Dorking STW River Mole 3 45 h 45m -
Thames Water Charlwood, surrey Mans Brook 4 37 h 15m -
Thames Water Castle Gardens (Dorking) SPS Mole 7 36 h 15m -
Thames Water Salfords SPS Salfords Stream 6 24 h 30m -
Thames Water Brockham Bridge XX SPS River Mole 2 23 h -
Thames Water Spooks hill, north holmwood Tanners Brook 8 22 h 676 h
Thames Water Stonebridge sso, brockham River Mole 3 21 h 45m -
Thames Water Canfold Wood (Ewhurst) SPS Thornhurst Brook 3 15 h 45m -
Thames Water Commonside (Leatherhead) SPS Bookham Brook 7 12 h -
Thames Water Boxhill SPS Into Land 9 11 h 15m 235 h
Thames Water Boxhill SPS Into Land 3 10 h -
Thames Water Capel SPS Deanoak Brook 3 9 h 45m -
Thames Water Ockley Road (Ewhurst) SPS Cobbler'S Brook 1 6 h -
Thames Water Spooks hill, north holmwood Tanners Brook 1 5 h 45m -
Thames Water Castle Gardens (Dorking) SPS Mole 1 5 h 45m -
Thames Water Salfords SPS Salfords Stream 1 5 h -
Thames Water River Lane (Leatherhead) SPS Mole 3 5 h -
Thames Water River Lane (Leatherhead) SPS Mole 0 0 h -
Thames Water Commonside (Leatherhead) SPS Bookham Brook 0 0 h -
Thames Water Dean Oak Lane (Leigh) SPS Deanoak Brook 0 0 h -

Data Sources & Accuracy

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.

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© 2020-2025 Top-Of-The-Poops CC-BY-SA 4.0,
© Openstreetmap contributors, Contains OS data © Crown copyright and database right 2021-2025,
Contains Water UK National Storm Overflow Hub Data CC-BY-SA 4.0 and analysis © 2025 Top-Of-The-Poops

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