Swindon STW

Storm overflow operated by Thames Water. The source names River Ray as the receiving water.

23
Spills in 2025: 287.8
Recorded hours: 99.9%
Monitor operation: 5
Years listed

The reported spill count was 24 lower than in 2024. This compares event counts, not discharge volume.

Current status unknown

Checking the latest monitor report…

How it compares in 2025

Swindon STW recorded 23 spills in 2025. That is more than 67% of the 14,239 overflows in England with a reported figure, and ranks 4,513th nationally. Among Thames Water overflows it ranks 150th of 579; the median Thames Water overflow recorded 6 spills.

Group	Rank by spills	Median spills	Median hours
This outlet	–	23	287.8
England	4,513th of 14,239	11	22.3
Thames Water	150th of 579	6	20.9

Rank 1 has the most spills. Equal counts share a rank. Only overflows with a reported count are ranked. Counts do not measure volume, so a higher rank does not mean more sewage.

Annual spill history

From 2021 to 2025, the reported count went from 22 to 23 spills. The highest count was 62 in 2023 and the lowest was 22 in 2021. The monitor worked for less than 90% of 2022, 2023, so those counts may be low.Amber bars mark years when the monitor worked for less than 90% of the year.

Year	Spills	Duration	Monitor operation	Source
2025	23	287.8 hours	99.9%	Official data
2024	47	621.5 hours	100%	Official data
2023	62	770.3 hours	89.5%Low coverage	Official data
2022	32	315.5 hours	86.9%Low coverage	Official data
2021	22	231.7 hours	100%	Official data

A missing figure means the source did not provide a usable value. A zero is shown as zero. Monitor operation below 90% can make comparison less reliable.

Outlet details

Water company: Thames Water
Outlet type: Storm tank at a wastewater treatment works, with treatment
Permit: CNTD.0017
Activity reference: A2
Grid reference: SU1275086010
Waterbody ID: GB106039023320Official waterbody record ↗
Location source: Official annual grid reference
Location precision: About 1 metres
Location note: Unknown

About the name and type

The annual return lists this asset as “Storm tank at WwTW - with treatment”: storm tank at a wastewater treatment works, with treatment. The overflow comes from storm storage at a treatment works. The return records this variant as discharging with treatment.

The waterbody link opens the Environment Agency record for the exact ID in the return. It is a source lookup; we do not import its classification.

Where it is

The recorded position is about 1.5 km west of the Swindon (Swindon) reference point in the ONS built-up areas data.

Area and water pages

Ray (Wiltshire) source to Lydiard Brook waterbody →

Check the official record

Public access to this outlet is unknown. Do not enter restricted land or use this page as a route guide.

Open official source ↗

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Questions about Swindon STW

Who operates Swindon STW?: Thames Water is the operator named in the annual record. The permit reference is CNTD.0017.
Where does Swindon STW discharge?: The source names River Ray as the receiving water. This does not show how far a discharge travelled.
How many times did Swindon STW spill in 2025?: The 2025 return records 23 counted spill events and 287.8 hours of recorded discharge. Spills are counted with the 12/24-hour method, so this is not a count of every start signal.
Can I trust the 2025 figures for this outlet?: The monitor worked for 99.9% of the reporting period, so the annual figures cover most of the year. They still do not measure discharge volume.
Is Swindon STW discharging right now?: This record is linked to a company live feed. The panel above shows the latest report we hold, with its date. That report can be old, and the monitor can be offline, so check the date before relying on it. A report that no discharge is taking place is not a water-quality result.
How accurate is the map marker?: The marker comes from the grid reference in the official annual return, which is accurate to about 1 metres. It shows the recorded outlet position, not the extent of any discharge.
What kind of outlet is Swindon STW?: The annual return lists the asset type as “Storm tank at WwTW - with treatment”, which means storm tank at a wastewater treatment works, with treatment. The overflow comes from storm storage at a treatment works. The return records this variant as discharging with treatment.
How does Swindon STW compare with other overflows?: Swindon STW recorded 23 spills in 2025. That is more than 67% of the 14,239 overflows in England with a reported figure, and ranks 4,513th nationally. Among Thames Water overflows it ranks 150th of 579; the median Thames Water overflow recorded 6 spills. Ranks compare counted spill events only. They do not compare volume or harm.
Does zero spills mean the water was safe?: No. A zero means the annual return recorded zero counted spill events for this outlet and year. It is not a water-quality test, and pollution can come from other sources.