Area of Outstanding Natural Beauty

Surrey Hills

Polluted by sewage 195 times in 2025 - lasting 1,827 hours

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Totals for Surrey Hills in 2025

11 Sites polluted by Southern Water Thames Water
195 sewage dumps
1,827 hours duration
Sewage pollution map of Surrey Hills
Sewage pollution map of Surrey Hills, showing 195 overflows in 2025
That's 2.54 months. 3.8 times a week, on average

How does Surrey Hills compare?

Surrey Hills was the #28 most polluted Area of Outstanding Natural Beauty in England & Wales, by duration of sewage overflows, as reported by the water companies

Why the change?

Storm overflows spill when it rains, and 2025 was drier than 2024 - 90% of average annual rainfall against 105%.

So much of any drop is weather, not fixed pipes. The live page shows rainfall and sewage side by side, day by day.

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Pollution Summary 2025

Here are all the reported sewage overflow totals for Surrey Hills in 2025.

How we count, and how accurate it is

A CSO Combined Sewage Overflow - a device that, when operating, pours combined rainwater & sewage into a waterway counts towards Surrey Hills when it sits inside the designated area, or within 200 metres of its boundary. An overflow close to two AONBs is counted in both.

We use data from the water companies, but we are seeing many anomalies that make us believe that location information is quite poor. The situation is likely far worse than reported here.

Other CSO Combined Sewage Overflow - a device that, when operating, pours combined rainwater & sewage into a waterway s just outside the 200 metre boundary are not counted, though they may still affect water quality inside the area.

Company Waterway Site Sewage Dumps Duration (Hours) Reporting %
Southern Water Chiddingfold Stream CHIDDINGFOLD WWTW 50 764 100
Southern Water Two S Of River Chidd GRAYSWOOD WWTW 52 309 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
Southern Water Freshwater River TURNERS MEAD P.S. 13 84 100
Thames Water Mole CASTLE GARDENS SPS 7 48 100
Southern Water Un River Arun HAMBLEDON PUMPING STATION 4 37 100
Thames Water Farnham Bourne WAVERLEY LANE SPS 4 32 100
Thames Water Into Land Box Hill 9 16 94.7
Thames Water Tanners Brook SPOOKS HILL 3 12 96.8
Thames Water Whitmoor Vale Stream CHURT SPS 4 8 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.