Union Street/CSO
Storm overflow operated by Yorkshire Water. The source names River Mas Culverted as the receiving water.
- 29
- Spills in 2025
- 40.8
- Recorded hours
- 100%
- Monitor operation
- 5
- Years listed
The reported spill count was 4 lower than in 2024. This compares event counts, not discharge volume.
Checking the latest monitor report…
How it compares in 2025
Union Street/CSO recorded 29 spills in 2025. That is more than 73% of the 14,239 overflows in England with a reported figure, and ranks 3,624th nationally. Among Yorkshire Water overflows it ranks 699th of 2,176; the median Yorkshire Water overflow recorded 16 spills. On the Don from Greasborough Dyke to River Dearne waterbody it ranks 13th of 37.
| Group | Rank by spills | Median spills | Median hours |
|---|---|---|---|
| This outlet | – | 29 | 40.8 |
| England | 3,624th of 14,239 | 11 | 22.3 |
| Yorkshire Water | 699th of 2,176 | 16 | 37.8 |
| Don from Greasborough Dyke to River Dearne | 13th of 37 | 15 | 72.8 |
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 | 29 | 40.8 hours | 100% | Official data |
| 2024 | 33 | 47 hours | 100% | Official data |
| 2023 | 44 | 56.6 hours | 100% | Official data |
| 2022 | 34 | 42.8 hours | 100% | Official data |
| 2021 | 39 | 30.4 hours | 99.6% | 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
- 3374
- Activity reference
- A1
- Grid reference
- SK4176092810
- Waterbody ID
- GB104027057452Official 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 1.5 km west of the Rotherham reference point in the ONS built-up areas data.
Area and water pages
- Waverley and Catcliffe area →
- Greasbrough area →
- Brinsworth area →
- Rotherham area →
- Sheffield area →
- Thorpe Hesley area →
- Ecclesfield and Grenoside area →
- Treeton area →
- Wentworth (Rotherham) area →
- Rawmarsh area →
- Whiston area →
- Jump area →
- Brampton (Rotherham) area →
- Hoyland area →
- Chapeltown and High Green area →
- Hemingfield area →
- Don from Greasborough Dyke to River Dearne 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
- Masbrough Street/CSOCurrent status unknown
Yorkshire Water · Holmes Tail Goit
- Psalters Lane Holmes/CSOCurrent status unknown
Yorkshire Water · Varies with Outlet
- Brinsworth Street/CSOCurrent status unknown
Yorkshire Water · Holmes Tail Goit
- Marsh Street/CSOCurrent status unknown
Yorkshire Water · River Don
Questions about Union Street/CSO
- Who operates Union Street/CSO?
- Yorkshire Water is the operator named in the annual record. The permit reference is 3374.
- Where does Union Street/CSO discharge?
- The source names River Mas Culverted as the receiving water. This does not show how far a discharge travelled.
- How many times did Union Street/CSO spill in 2025?
- The 2025 return records 29 counted spill events and 40.8 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 Union Street/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 Union Street/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 Union Street/CSO compare with other overflows?
- Union Street/CSO recorded 29 spills in 2025. That is more than 73% of the 14,239 overflows in England with a reported figure, and ranks 3,624th nationally. Among Yorkshire Water overflows it ranks 699th of 2,176; the median Yorkshire Water overflow recorded 16 spills. On the Don from Greasborough Dyke to River Dearne waterbody it ranks 13th of 37. 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.