Clarence Street CSO
Storm overflow operated by United Utilities. The source names River Darwen as the receiving water.
- 42
- Spills in 2025
- 69.1
- Recorded hours
- 99.2%
- Monitor operation
- 2
- 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
Clarence Street CSO recorded 42 spills in 2025. That is more than 83% of the 14,239 overflows in England with a reported figure, and ranks 2,238th nationally. Among United Utilities overflows it ranks 554th of 2,270; the median United Utilities overflow recorded 15 spills. On the Darwen - headwaters to conf Davy Field Bk waterbody it ranks 7th of 26.
| Group | Rank by spills | Median spills | Median hours |
|---|---|---|---|
| This outlet | – | 42 | 69.1 |
| England | 2,238th of 14,239 | 11 | 22.3 |
| United Utilities | 554th of 2,270 | 15 | 29.1 |
| Darwen - headwaters to conf Davy Field Bk | 7th of 26 | 8 | 4.7 |
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 | 42 | 69.1 hours | 99.2% | Official data |
| 2024 | 46 | 101.3 hours | 98.9% | 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
- United Utilities
- Outlet type
- Storm overflow on the sewer network
- Permit
- 017190797
- Activity reference
- A1
- Grid reference
- SD6871023540
- Waterbody ID
- GB112071065240Official 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 1.2 km north-west of the Darwen 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
- Lower Eccleshill Road CSOCurrent status unknown
United Utilities · River Darwen
- Cotton Hall Street CSOCurrent status unknown
United Utilities · Tributary of River Darwen
- Hindle Street CSOCurrent status unknown
United Utilities · River Darwen via SWS
- Woodvale Flats combined sewer overflow (059AF) (BBN0151)Current status unknown
United Utilities · River Darwen
Questions about Clarence Street CSO
- Who operates Clarence Street CSO?
- United Utilities is the operator named in the annual record. The permit reference is 017190797.
- Where does Clarence Street CSO discharge?
- The source names River Darwen as the receiving water. This does not show how far a discharge travelled.
- How many times did Clarence Street CSO spill in 2025?
- The 2025 return records 42 counted spill events and 69.1 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 99.2% of the reporting period, so the annual figures cover most of the year. They still do not measure discharge volume.
- Is Clarence 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 Clarence 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 Clarence Street CSO compare with other overflows?
- Clarence Street CSO recorded 42 spills in 2025. That is more than 83% of the 14,239 overflows in England with a reported figure, and ranks 2,238th nationally. Among United Utilities overflows it ranks 554th of 2,270; the median United Utilities overflow recorded 15 spills. On the Darwen - headwaters to conf Davy Field Bk waterbody it ranks 7th of 26. 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.