Thames Water

was responsible for 8,014 sewage overflows in 2022
On average 22 times a day

These lasted for 74,693 hours (That's 8.65 years!) - in 378 different locations across their service area

Percentage of all EDMs overflowing

We have live data for Thames Water so we can track what happens every day - given that overflows are supposed to happen on an 'exceptional' basis only - does the chart indicate that?

The red line indicates the number of CSOs that overflowed for at least 30mins, the grey, the number of CSOs that were offline for at least 30mins

There is daily updated information on all constituencies covered by Thames Water

Here we can see a plot of the number of days across the Thames Water area that CSOs overflowed, correlated with the amount of local rainfall, as reported by the Environment Agency Rainfall Monitoring Stations.

We take the 75th percentile of all the rainfall monitoring stations in or near the constituency where the CSO is located, and plot that against how long each CSO overflowed.

Worst Locations Thames Water

1. STEWKLEY WASTEWATER TREATMENT WORKS

Buckingham polluted for 1,931 hours, into Hardwick Brook

107 incidents

That's 2.68 months.

2.1 times a week, on average

2. MORTIMER (STRATFIELD MORTIMER) WWTW

Wokingham polluted for 1,641 hours, into Foudry Brook

84 incidents

That's 2.28 months.

1.6 times a week, on average

3. SOUTH LEIGH WWTW

Witney polluted for 1,482 hours, into Limb Brook

74 incidents

That's 2.06 months.

1.4 times a week, on average

4. WINGRAVE WASTEWATER TREATMENT WORKS

Buckingham polluted for 1,433 hours, into Rowsham Brook

89 incidents

That's 1.99 months.

1.7 times a week, on average

5. SILCHESTER WWTW

North East Hampshire polluted for 1,239 hours, into Sichester Brook

74 incidents

That's 1.72 months.

1.4 times a week, on average

6. HATFIELD HEATH WWTW

Saffron Walden polluted for 1,234 hours, into Hatfield Heath Watercourse

70 incidents

That's 1.71 months.

1.3 times a week, on average

Water Companies

Data Sources & Accuracy

EDM (Event Duration Monitoring) data and Consented Discharges to Controlled Waters with Conditions from Environment Agency & Data Map Wales

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.