Thornhill Road/CSO
Storm overflow operated by Yorkshire Water. The source names Smithy Brook as the receiving water.
- 3
- Spills in 2025
- 33.8
- Recorded hours
- 26.7%
- Monitor operation
- 6
- Years listed
Checking the latest monitor report…
How it compares in 2025
Thornhill Road/CSO recorded 3 spills in 2025. That is more than 26% of the 14,239 overflows in England with a reported figure, and ranks 9,843rd nationally. Among Yorkshire Water overflows it ranks 1,632nd of 2,176; the median Yorkshire Water overflow recorded 16 spills. On the Smithy Brook from Source to River Calder waterbody it ranks 2nd of 4.
The monitor worked for 26.7% of 2025, so this count may be low and its rank may understate activity.
| Group | Rank by spills | Median spills | Median hours |
|---|---|---|---|
| This outlet | – | 3 | 33.8 |
| England | 9,843rd of 14,239 | 11 | 22.3 |
| Yorkshire Water | 1,632nd of 2,176 | 16 | 37.8 |
| Smithy Brook from Source to River Calder | 2nd of 4 | 3 | 17.6 |
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 | 3 | 33.8 hours | 26.7%Low coverage | Official data |
| 2024 | 14 | 26 hours | 90%Low coverage | Official data |
| 2023 | 7 | 17 hours | 77%Low coverage | Official data |
| 2022 | 14 | 23 hours | 99.9% | Official data |
| 2021 | 12 | 41.3 hours | 57.8%Low coverage | Official data |
| 2020 | 6 | 13.6 hours | 94.5% | 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 overflow on the sewer network
- Permit
- 2094
- Activity reference
- 1
- Grid reference
- SE2671017940
- Waterbody ID
- GB104027062510Official 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 “SO on sewer network”: storm overflow on the sewer network. The return places this overflow on the sewer network.
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 0.9 km north of the Middlestown and Overton reference point in the ONS built-up areas data.
Area and water pages
- Morley (Leeds) area →
- Kirkheaton area →
- Moor Top area →
- Liversedge area →
- Mirfield area →
- Lepton area →
- East Ardsley area →
- Heckmondwike area →
- Thorpe on the Hill (Leeds) area →
- Grange Moor area →
- Batley area →
- Dewsbury area →
- Kirkburton area →
- Kirkhamgate area →
- Smithy Brook from Source to River Calder 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 ↗Other outlet records nearby
- Bridge Road/CSOCurrent status unknown
Yorkshire Water · Smithy Brook
- Healey Road Ossett/CSOCurrent status unknown
Yorkshire Water · River Calder
- Horbury Bridge/No 2 CSOCurrent status unknown
Yorkshire Water · River Calder
- Swallows Nest/CSOCurrent status unknown
Yorkshire Water · Tributary of River Calder
Questions about Thornhill Road/CSO
- Who operates Thornhill Road/CSO?
- Yorkshire Water is the operator named in the annual record. The permit reference is 2094.
- Where does Thornhill Road/CSO discharge?
- The source names Smithy Brook as the receiving water. This does not show how far a discharge travelled.
- How many times did Thornhill Road/CSO spill in 2025?
- The 2025 return records 3 counted spill events and 33.8 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 26.7% of the reporting period. Below 90%, some events can be missed, so the count and hours may understate activity.
- Is Thornhill Road/CSO 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 Thornhill Road/CSO?
- The annual return lists the asset type as “SO on sewer network”, which means storm overflow on the sewer network. The return places this overflow on the sewer network.
- How does Thornhill Road/CSO compare with other overflows?
- Thornhill Road/CSO recorded 3 spills in 2025. That is more than 26% of the 14,239 overflows in England with a reported figure, and ranks 9,843rd nationally. Among Yorkshire Water overflows it ranks 1,632nd of 2,176; the median Yorkshire Water overflow recorded 16 spills. On the Smithy Brook from Source to River Calder waterbody it ranks 2nd of 4. 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.