Offwell STW So Offwell

Storm overflow operated by South West Water. The source names Tributary of Offwell Brook as the receiving water.

71
Spills in 2025: 1,124.4
Recorded hours: 100%
Monitor operation: 5
Years listed

The reported spill count was 30 higher than in 2024. This compares event counts, not discharge volume.

Current status unknown

Checking the latest monitor report…

How it compares in 2025

Offwell STW So Offwell recorded 71 spills in 2025. That is more than 94% of the 14,239 overflows in England with a reported figure, and ranks 743rd nationally. Among South West Water overflows it ranks 215th of 1,357; the median South West Water overflow recorded 21 spills.

Group	Rank by spills	Median spills	Median hours
This outlet	–	71	1,124.4
England	743rd of 14,239	11	22.3
South West Water	215th of 1,357	21	39.4

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 27 to 71 spills. The highest count was 77 in 2023 and the lowest was 27 in 2021. The monitor worked for less than 90% of 2023, so that count 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	71	1,124.4 hours	100%	Official data
2024	41	426.7 hours	92.6%	Official data
2023	77	531.4 hours	81.8%Low coverage	Official data
2022	56	407.4 hours	100%	Official data
2021	27	145.5 hours	92%	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: South West Water
Outlet type: Inlet storm overflow at a wastewater treatment works
Permit: 200366
Activity reference: A2
Grid reference: SY19169889
Waterbody ID: GB108045008840Official waterbody record ↗
Location source: Official annual grid reference
Location precision: About 10 metres
Location note: Unknown

About the name and type

The annual return lists this asset as “Inlet SO at WwTW”: inlet storm overflow at a wastewater treatment works. The overflow is at the inlet of a treatment works, where wastewater enters the works.

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 0.7 km south of the Offwell reference point in the ONS built-up areas data.

Area and water pages

Offwell 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 Offwell STW So Offwell

Who operates Offwell STW So Offwell?: South West Water is the operator named in the annual record. The permit reference is 200366.
Where does Offwell STW So Offwell discharge?: The source names Tributary of Offwell Brook as the receiving water. This does not show how far a discharge travelled.
How many times did Offwell STW So Offwell spill in 2025?: The 2025 return records 71 counted spill events and 1,124.4 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 100% of the reporting period, so the annual figures cover most of the year. They still do not measure discharge volume.
Is Offwell STW So Offwell 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 10 metres. It shows the recorded outlet position, not the extent of any discharge.
What kind of outlet is Offwell STW So Offwell?: The annual return lists the asset type as “Inlet SO at WwTW”, which means inlet storm overflow at a wastewater treatment works. The overflow is at the inlet of a treatment works, where wastewater enters the works.
How does Offwell STW So Offwell compare with other overflows?: Offwell STW So Offwell recorded 71 spills in 2025. That is more than 94% of the 14,239 overflows in England with a reported figure, and ranks 743rd nationally. Among South West Water overflows it ranks 215th of 1,357; the median South West Water overflow recorded 21 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.