Chorley WwTW
Storm overflow operated by United Utilities. The source names River Yarrow & Chor as the receiving water.
- 18
- Spills in 2025
- 105.9
- Recorded hours
- 95.7%
- Monitor operation
- 2
- Years listed
The reported spill count was 2 lower than in 2024. This compares event counts, not discharge volume.
Checking the latest monitor report…
How it compares in 2025
Chorley WwTW recorded 18 spills in 2025. That is more than 60% of the 14,239 overflows in England with a reported figure, and ranks 5,407th nationally. Among United Utilities overflows it ranks 1,054th of 2,270; the median United Utilities overflow recorded 15 spills. On the Yarrow DS Big Lodge Water waterbody it ranks 10th of 19.
| Group | Rank by spills | Median spills | Median hours |
|---|---|---|---|
| This outlet | – | 18 | 105.9 |
| England | 5,407th of 14,239 | 11 | 22.3 |
| United Utilities | 1,054th of 2,270 | 15 | 29.1 |
| Yarrow DS Big Lodge Water | 10th of 19 | 18 | 19.8 |
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 | 18 | 105.9 hours | 95.7% | Official data |
| 2024 | 20 | 134.7 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
- United Utilities
- Outlet type
- Storm tank at a wastewater treatment works
- Permit
- 017060016
- Activity reference
- A2
- Grid reference
- SD5638217462
- Waterbody ID
- GB112070064952Official 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 1.9 km west of the Chorley 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
- Chorley Lower Works PSCurrent status unknown
United Utilities · River Yarrow
- Common Bank Lane CSOCurrent status unknown
United Utilities · River Chor Diversion Channel
- Parklands CSOCurrent status unknown
United Utilities · River Chor Tributary River Yarrow
- Lydd Grove PSCurrent status unknown
United Utilities · Unnamed Tributary of River Chor
Questions about Chorley WwTW
- Who operates Chorley WwTW?
- United Utilities is the operator named in the annual record. The permit reference is 017060016.
- Where does Chorley WwTW discharge?
- The source names River Yarrow & Chor as the receiving water. This does not show how far a discharge travelled.
- How many times did Chorley WwTW spill in 2025?
- The 2025 return records 18 counted spill events and 105.9 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 95.7% of the reporting period, so the annual figures cover most of the year. They still do not measure discharge volume.
- Is Chorley WwTW 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 Chorley WwTW?
- 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 Chorley WwTW compare with other overflows?
- Chorley WwTW recorded 18 spills in 2025. That is more than 60% of the 14,239 overflows in England with a reported figure, and ranks 5,407th nationally. Among United Utilities overflows it ranks 1,054th of 2,270; the median United Utilities overflow recorded 15 spills. On the Yarrow DS Big Lodge Water waterbody it ranks 10th of 19. 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.