Horbury/STW
Storm overflow operated by Yorkshire Water. The source names River Calder as the receiving water.
- 82
- Spills in 2025
- 928.3
- Recorded hours
- 100%
- Monitor operation
- 4
- Years listed
The reported spill count was 8 lower than in 2024. This compares event counts, not discharge volume.
Checking the latest monitor report…
How it compares in 2025
Horbury/STW recorded 82 spills in 2025. That is more than 96% of the 14,239 overflows in England with a reported figure, and ranks 476th nationally. Among Yorkshire Water overflows it ranks 67th of 2,176; the median Yorkshire Water overflow recorded 16 spills. On the Calder from River Colne to River Chald waterbody it ranks 1st of 41.
| Group | Rank by spills | Median spills | Median hours |
|---|---|---|---|
| This outlet | – | 82 | 928.3 |
| England | 476th of 14,239 | 11 | 22.3 |
| Yorkshire Water | 67th of 2,176 | 16 | 37.8 |
| Calder from River Colne to River Chald | 1st of 41 | 20 | 69 |
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 | 82 | 928.3 hours | 100% | Official data |
| 2024 | 90 | 820.5 hours | 100% | Official data |
| 2023 | 151 | 2,229 hours | 97% | Official data |
| 2022 | 53 | 226.8 hours | 99.9% | 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
- Yorkshire Water
- Outlet type
- Storm tank at a wastewater treatment works
- Permit
- C4107
- Activity reference
- A2
- Grid reference
- SE3000017070
- Waterbody ID
- GB104027062631Official 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”: storm tank at a wastewater treatment works. The overflow comes from storm storage at a treatment 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 1.2 km north-west of the Crigglestone and Durkar 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
- Horbury/STW/6Xdwf OverflowCurrent status unknown
Yorkshire Water · River Calder
- Charles Street/No 2 CSOCurrent status unknown
Yorkshire Water · Old Mill Stream
- Great Cliff/SPSCurrent status unknown
Yorkshire Water · Dennington Beck
- Ossett Spa/CSOCurrent status unknown
Yorkshire Water · River Calder
Questions about Horbury/STW
- Who operates Horbury/STW?
- Yorkshire Water is the operator named in the annual record. The permit reference is C4107.
- Where does Horbury/STW discharge?
- The source names River Calder as the receiving water. This does not show how far a discharge travelled.
- How many times did Horbury/STW spill in 2025?
- The 2025 return records 82 counted spill events and 928.3 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 Horbury/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 Horbury/STW?
- 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 Horbury/STW compare with other overflows?
- Horbury/STW recorded 82 spills in 2025. That is more than 96% of the 14,239 overflows in England with a reported figure, and ranks 476th nationally. Among Yorkshire Water overflows it ranks 67th of 2,176; the median Yorkshire Water overflow recorded 16 spills. On the Calder from River Colne to River Chald waterbody it ranks 1st of 41. 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.