St John S T Septnk So St John

Storm overflow operated by South West Water. The source names St Johns Leat (E) as the receiving water.

42
Spills in 2025: 32.7
Recorded hours: 97.7%
Monitor operation: 5
Years listed

Current status unknown

Checking the latest monitor report…

How it compares in 2025

St John S T Septnk So St John recorded 42 spills in 2025. That is more than 83% of the 14,239 overflows in England with a reported figure, and ranks 2,238th nationally. Among South West Water overflows it ranks 410th of 1,357; the median South West Water overflow recorded 21 spills.

Group	Rank by spills	Median spills	Median hours
This outlet	–	42	32.7
England	2,238th of 14,239	11	22.3
South West Water	410th 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 4 to 42 spills. The highest count was 42 in 2025 and the lowest was 4 in 2021. The monitor worked for less than 90% of 2022, 2024, 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	42	32.7 hours	97.7%	Official data
2024	16	8.8 hours	80.6%Low coverage	Official data
2023	15	18 hours	100%	Official data
2022	13	53.4 hours	89%Low coverage	Official data
2021	4	1.5 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: South West Water
Outlet type: Inlet storm overflow at a wastewater treatment works
Permit: 302135
Activity reference: A2
Grid reference: SX40965376
Waterbody ID: Unknown
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.

Where it is

The recorded position is about 2.1 km north-west of the Millbrook reference point in the ONS built-up areas data.

Designated bathing waters within 3 km in a straight line:

Distance does not show that water from this outlet reaches a bathing water. Check the official bathing-water profile for its classification and advice.

Area and water pages

Plymouth area →

Check the official record

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

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Questions about St John S T Septnk So St John

Who operates St John S T Septnk So St John?: South West Water is the operator named in the annual record. The permit reference is 302135.
Where does St John S T Septnk So St John discharge?: The source names St Johns Leat (E) as the receiving water. This does not show how far a discharge travelled.
How many times did St John S T Septnk So St John spill in 2025?: The 2025 return records 42 counted spill events and 32.7 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 97.7% of the reporting period, so the annual figures cover most of the year. They still do not measure discharge volume.
Is St John S T Septnk So St John 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 St John S T Septnk So St John?: 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 St John S T Septnk So St John compare with other overflows?: St John S T Septnk So St John recorded 42 spills in 2025. That is more than 83% of the 14,239 overflows in England with a reported figure, and ranks 2,238th nationally. Among South West Water overflows it ranks 410th 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.