Dorking and Horley

Polluted by sewage 411 times in 2025 lasting 4,872 hours

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

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Live data for Dorking and Horley in 2026

So far this year (as of 25 Oct 2026, 17:45) there has been 3,368 hours of sewage overflows, from 34 CSO Combined Sewage Overflow - a device that, when operating, pours combined rainwater & sewage into a waterway s

Sewage without rain in Dorking and Horley

On 6 occasions since December 2024, no rain fell anywhere in Dorking and Horley for days — and its CSO Combined Sewage Overflow - a device that, when operating, pours combined rainwater & sewage into a waterway s discharged anyway.

Totals for Dorking and Horley in 2025

17 Sites polluted by Thames Water
411 sewage dumps
4,872 hours duration
Sewage pollution map of Dorking and Horley
Sewage pollution map of Dorking and Horley: 411 spills in 2025, lasting 4,872 hours, by Thames Water
That's 6.77 months. On average 1.1 times a day

Change Over Time

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Pollution Summary 2025

Here are all the reported sewage overflow totals for Dorking and Horley in 2025. Sometimes sewage can be being dumped for months at a time.

Reporting refers to how much of the time the monitoring was active. In this constituency all the declared CSO Combined Sewage Overflow - a device that, when operating, pours combined rainwater & sewage into a waterway s appeared to have monitoring enabled for more than 50% of the year

Company Waterway Site Sewage Dumps Duration (Hours) Reporting %
Thames Water River Mole IRONSBOTTOM (SIDLOW) WWTW 70 1,095 99.9
Thames Water Burstow Stream BURSTOW STW, HATHERSHAM ROAD, SMALL 72 1,040 99.4
Thames Water Mole LEE STREET 59 835 86.5
Thames Water Holmwood Stm Leigh Brk HOLMWOOD SEWAGE TREATMENT WORKS 61 819 99.9
Thames Water River Mole DORKING STW (STORM) 23 296 99.2
Thames Water River Mole COACH ROAD CSO ON STONEBRIDGE SEWER 26 218 98.1
Thames Water Mans Brook CHARLWOOD, SURREY 25 166 92.2
Thames Water Thornhurst Brook Canfold Wood 13 82 99.6
Thames Water River Mole Brockham Bridge 8 71 100
Thames Water Deanoak Brook CSO AT CAPEL SPS 15 67 99
Thames Water Cobbler'S Brook Ockley Road 9 63 91.8
Thames Water Mole CASTLE GARDENS SPS 7 48 100
Thames Water Salfords Stream SALFORDS SEWAGE PUMPING STATION 7 29 100
Thames Water Into Land Box Hill 9 16 94.7
Thames Water Tanners Brook SPOOKS HILL, NORTH HOLMWOOD, SURREY 3 12 96.8
Thames Water Bookham Brook Commonside 2 5 99.7
Thames Water Mole RIVER LANE PUMPING STATION, FETCHAM 2 5 100
Thames Water Deanoak Brook Dean Oak Lane 0 0 100
Thames Water Tanners Brook SURFACE WATER SEWER 0 0 99.9

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

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.