Calne Inlet
Storm overflow operated by Wessex Water. The source names River Marden(S) as the receiving water.
- 21
- Spills in 2025
- 43.8
- Recorded hours
- 100%
- Monitor operation
- 6
- Years listed
The reported spill count was 17 lower than in 2024. This compares event counts, not discharge volume.
Checking the latest monitor report…
How it compares in 2025
Calne Inlet recorded 21 spills in 2025. That is more than 64% of the 14,239 overflows in England with a reported figure, and ranks 4,856th nationally. Among Wessex Water overflows it ranks 434th of 1,332; the median Wessex Water overflow recorded 11 spills. On the Marden - source to conf Cowage Bk waterbody it ranks 4th of 12.
| Group | Rank by spills | Median spills | Median hours |
|---|---|---|---|
| This outlet | – | 21 | 43.8 |
| England | 4,856th of 14,239 | 11 | 22.3 |
| Wessex Water | 434th of 1,332 | 11 | 18.9 |
| Marden - source to conf Cowage Bk | 4th of 12 | 11 | 38.8 |
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 | 21 | 43.8 hours | 100% | Official data |
| 2024 | 38 | 119.6 hours | 100% | Official data |
| 2023 | 56 | 120.2 hours | 100% | Official data |
| 2022 | 20 | 38.3 hours | 100% | Official data |
| 2021 | 16 | 13.5 hours | 99.2% | Official data |
| 2020 | 34 | 112 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
- Wessex Water
- Outlet type
- Inlet storm overflow at a wastewater treatment works
- Permit
- 103731
- Activity reference
- 3-STORM DISCHARGE AT STW (UNTREATED)
- Grid reference
- ST9791071440
- Waterbody ID
- GB109053022050Official 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 “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 1.5 km east of the Derry Hill and Studley reference point in the ONS built-up areas data.
Area and water pages
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
- Calne Storm TankCurrent status unknown
Wessex Water · River Marden(S)
- Calne Mosses Mill 1Current status unknown
Wessex Water · River Marden
- Calne Mosses Mill 2Current status unknown
Wessex Water · River Marden
- Calne River Marden (River Bank) South Marden House New RoadCurrent status unknown
Wessex Water · River Marden
Questions about Calne Inlet
- Who operates Calne Inlet?
- Wessex Water is the operator named in the annual record. The permit reference is 103731.
- Where does Calne Inlet discharge?
- The source names River Marden(S) as the receiving water. This does not show how far a discharge travelled.
- How many times did Calne Inlet spill in 2025?
- The 2025 return records 21 counted spill events and 43.8 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 Calne Inlet 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 Calne Inlet?
- 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 Calne Inlet compare with other overflows?
- Calne Inlet recorded 21 spills in 2025. That is more than 64% of the 14,239 overflows in England with a reported figure, and ranks 4,856th nationally. Among Wessex Water overflows it ranks 434th of 1,332; the median Wessex Water overflow recorded 11 spills. On the Marden - source to conf Cowage Bk waterbody it ranks 4th of 12. 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.