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Area of Outstanding Natural Beauty

Chilterns - 2025 Sewage

Polluted by sewage 764 hours in 2025 , monitoring offline 1,079 hours

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

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Totals for 2025

Sewage764 hours
Monitoring offline1,079 hours
Potential pollution0 hours
Storm overflows14

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Daily Data - when it rained, and when they spilled

Square = rainfall none → heavy
Drop = sewage minutes → all day
Potential pollution Monitoring offline
Jan - 395 hours , 376 offline
Feb - 191 hours
Mar - 104 hours
Apr - 12 hours
May - 2 hours
Jun - 0 hours
Jul - 0 hours
Aug - 0 hours
Sept - 2 hours , 185 offline
Oct - 2 hours , 517 offline
Nov - 22 hours
Dec - 30 hours

Storm overflows in and around Chilterns

Company Site Name Receiving Waterway Overflow Days Total Duration (hours) Offline/Potential Pollution
Thames Water Amersham balancing tanks/amersham vale stk Misbourne 29 437h 15m 702 h
Thames Water Berkhamsted STW Grand Union Canal 32 202h 15m -
Thames Water Chesham STW River Chess 6 53h 30m -
Thames Water Dagnall STW Groundwater Via Infilt System 11 38h 15m -
Thames Water Dagnall STW Groundwater Via Infilt System 5 20h 30m -
Thames Water Berkhamsted STW Grand Union Canal 1 6h -
Thames Water Chesham STW River Chess 1 4h 15m -
Thames Water Sonning Common STW Into Land 1 1h 30m -
Thames Water Watery Lane (Marsworth) SPS Tring Bourne 1 0h 30m -
Thames Water Hambleden STW River Thames 0 0h -
Thames Water Amersham balancing tanks/amersham vale stk Misbourne 0 0h -
Thames Water Hambleden STW River Thames 0 0h 376 h
Thames Water Sonning Common STW Into Land 0 0h -
Thames Water Tring STW Into Guc/Reservoir 0 0h -

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.