Gunnislake STW SSO Gunnislake
Storm overflow operated by South West Water. The source names River Tamar (Estuarine) as the receiving water.
- 94
- Spills in 2025
- 955.8
- Recorded hours
- 100%
- Monitor operation
- 5
- Years listed
The reported spill count was 67 lower than in 2024. This compares event counts, not discharge volume.
Checking the latest monitor report…
How it compares in 2025
Gunnislake STW SSO Gunnislake recorded 94 spills in 2025. That is more than 97% of the 14,239 overflows in England with a reported figure, and ranks 307th nationally. Among South West Water overflows it ranks 111th of 1,357; the median South West Water overflow recorded 21 spills.
| Group | Rank by spills | Median spills | Median hours |
|---|---|---|---|
| This outlet | – | 94 | 955.8 |
| England | 307th of 14,239 | 11 | 22.3 |
| South West Water | 111th 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
| Year | Spills | Duration | Monitor operation | Source |
|---|---|---|---|---|
| 2025 | 94 | 955.8 hours | 100% | Official data |
| 2024 | 161 | 3,051.3 hours | 100% | Official data |
| 2023 | 124 | 2,351.1 hours | 99.2% | Official data |
| 2022 | 57 | 146.6 hours | 99% | Official data |
| 2021 | 53 | 179.8 hours | 99% | 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
- Storm tank at a wastewater treatment works
- Permit
- SWWA 2413
- Activity reference
- A2
- Grid reference
- SX43437067
- 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 “Storm tank at WwTW”: storm tank at a wastewater treatment works. The overflow comes from storm storage at a treatment works.
Where it is
The recorded position is about 1.1 km east of the Gunnislake and St Ann's Chapel reference point in the ONS built-up areas data.
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 ↗Other outlet records nearby
- Gunnislake STW So GunnislakeCurrent status unknown
South West Water · River Tamar (Estuarine)
- Kingswood Road SPS Pscsoeo GunnislakeCurrent status unknown
South West Water · River Tamar
- Gunnislake No. 1 CSO GunnislakeCurrent status unknown
South West Water · River Tamar (S)
- Gunnislake No. 2 CSO GunnislakeCurrent status unknown
South West Water · River Tamar via SWS
Questions about Gunnislake STW SSO Gunnislake
- Who operates Gunnislake STW SSO Gunnislake?
- South West Water is the operator named in the annual record. The permit reference is SWWA 2413.
- Where does Gunnislake STW SSO Gunnislake discharge?
- The source names River Tamar (Estuarine) as the receiving water. This does not show how far a discharge travelled.
- How many times did Gunnislake STW SSO Gunnislake spill in 2025?
- The 2025 return records 94 counted spill events and 955.8 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 100% of the reporting period, so the annual figures cover most of the year. They still do not measure discharge volume.
- Is Gunnislake STW SSO Gunnislake 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 Gunnislake STW SSO Gunnislake?
- The annual return lists the asset type as “Storm tank at WwTW”, which means storm tank at a wastewater treatment works. The overflow comes from storm storage at a treatment works.
- How does Gunnislake STW SSO Gunnislake compare with other overflows?
- Gunnislake STW SSO Gunnislake recorded 94 spills in 2025. That is more than 97% of the 14,239 overflows in England with a reported figure, and ranks 307th nationally. Among South West Water overflows it ranks 111th 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.