Scottish Water

was responsible for at least 21,660 sewage overflows in 2023
On average 59.3 times a day

These lasted for 221,002 hours (That's 25.58 years!) - in 210 different locations across their service area

Special Note regarding Scottish Water

Scottish Water simply does not monitor the overflows of many of its CSOs, - so the numbers here are artificially low, the real situation is far worse.

Of the 702 CSOs locations we know about for Scottish Water, 452 of them have ZERO reporting.

2023 - By Water Company

How does each water company compare? These are the totals by company for each. The totals are really high, counting things in hours doesn't make it very easy to think about. Here we show how many years of continuous sewage dumps happened in a single year, by water company.

2023 - Asset Spill Duration Comparison

It isn't like there are just a few outliers... the problem exists across the entire estate of water assets. Here we show a 'cumulative frequency diagram' - where the number of CSOs that dumped sewage for a time, or longer, is shown. You can see that many CSOs dumped sewage into a river for months and months.

Scottish Water is highlighted in the plot below

2023 - Worst Locations Scottish Water

1. DALDERSE WWTW 1966 NS903822

Falkirk polluted for 16,949 hours, into River Carron

280 incidents

That's 1.96 years!

5.4 times a week, on average

2. BIGGAR WWTW 2002 NT049369

Dumfriesshire, Clydesdale and Tweeddale polluted for 8,855 hours, into Biggar Burn

243 incidents

That's 1.02 years!

4.7 times a week, on average


Argyll and Bute polluted for 7,686 hours, into Clyde Estuary

1,521 incidents

That's 10.68 months.

On average 4.2 times a day

4. THORNHILL WWTW 1930 NX872950

Dumfriesshire, Clydesdale and Tweeddale polluted for 6,945 hours, into River Nith

328 incidents

That's 9.65 months.

6.3 times a week, on average

5. LINCLUDEN WWTW 1930 NX963780

Dumfries and Galloway polluted for 6,726 hours, into Cluden Water

980 incidents

That's 9.34 months.

On average 2.7 times a day

6. TOR-NA-DEE SPS NS168754

Argyll and Bute polluted for 5,518 hours, into Clyde Estuary/Firth of Clyde

57 incidents

That's 7.66 months.

1.1 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, 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.