Dorking and Horley was polluted by sewage 643 times in 2024
lasting 7,704 hours

Constituency

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✔ means we have experimental daily data since 2023

Live data for Dorking and Horley in 2025

So far this year (as of Apr 16, 2025, 5:45 PM) there has been 1,813 hours of sewage overflows

Totals for Dorking and Horley in 2024

18 Sites polluted by Thames Water

643 sewage dumps
7,704 h duration

That's 10.7 months. On average 1.8 times a day

Change Over Time

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Constituencies near Dorking and Horley

Waterways in Dorking and Horley

Daily Data

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.

Monitoring Online Monitoring Offline Polluting Potentially Polluting Unknown

Daily data is experimental and data is not guaranteed to be accurate. Please inform us of any issue, we will fix.

Pollution Summary 2024

Here are all the reported sewage overflow totals for Dorking and Horley in 2024. 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 0 of the total 19 CSO locations had reporting enabled for less than half the year, of which 0 had zero reporting.

Company	Waterway	Site	Sewage Dumps	Duration (Hours)	Reporting %
Thames Water	Burstow Stream	BURSTOW STW, HATHERSHAM ROAD, SMALL	133	1,758	99.6
Thames Water	Holmwood Stm Leigh Brk	HOLMWOOD SEWAGE TREATMENT WORKS	107	1,630	99.9
Thames Water	Mole	LEE STREET	91	1,444	99.7
Thames Water	River Mole	DORKING STW (STORM)	69	978	99.5
Thames Water	River Mole	IRONSBOTTOM (SIDLOW) WWTW	63	858	86.2
Thames Water	Mans Brook	CHARLWOOD, SURREY	35	268	98.5
Thames Water	River Mole	Brockham Bridge	15	122	99.9
Thames Water	Thornhurst Brook	Canfold Wood	26	122	99.9
Thames Water	River Mole	COACH ROAD CSO ON STONEBRIDGE SEWER	11	121	36.3
Thames Water	Mole	CASTLE GARDENS SPS	12	119	100
Thames Water	Deanoak Brook	CSO AT CAPEL SPS	22	89	99.4
Thames Water	Into Land	Box Hill	9	46	90.6
Thames Water	Bookham Brook	Commonside	13	37	99.8
Thames Water	Tanners Brook	SPOOKS HILL, NORTH HOLMWOOD, SURREY	12	36	99.9
Thames Water	Salfords Stream	SALFORDS SEWAGE PUMPING STATION	8	35	99.9
Thames Water	Cobbler'S Brook	Ockley Road	7	17	100
Thames Water	Mole	RIVER LANE PUMPING STATION, FETCHAM	6	10	99.5
Thames Water	Tanners Brook	SURFACE WATER SEWER	4	8	100
Thames Water	Deanoak Brook	Dean Oak Lane	0	0	100

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. This 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.

Analysing sewage pollution by the Water Industry

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