Dunham Massey Outfall SSO
Storm overflow operated by United Utilities. The source names River Bollin via SWS as the receiving water.
- 43
- Spills in 2025
- 166.8
- Recorded hours
- 95.4%
- 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
Dunham Massey Outfall SSO recorded 43 spills in 2025. That is more than 84% of the 14,239 overflows in England with a reported figure, and ranks 2,156th nationally. Among United Utilities overflows it ranks 534th of 2,270; the median United Utilities overflow recorded 15 spills. On the Bollin (Ashley Mill to Manchester Ship Canal) waterbody it ranks 3rd of 7.
| Group | Rank by spills | Median spills | Median hours |
|---|---|---|---|
| This outlet | – | 43 | 166.8 |
| England | 2,156th of 14,239 | 11 | 22.3 |
| United Utilities | 534th of 2,270 | 15 | 29.1 |
| Bollin (Ashley Mill to Manchester Ship Canal) | 3rd of 7 | 43 | 166.8 |
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 | 43 | 166.8 hours | 95.4% | Official data |
| 2024 | 47 | 176.2 hours | 99.4% | 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
- 01TRA0079
- Activity reference
- A1
- Grid reference
- SJ7269087541
- Waterbody ID
- GB112069061382Official 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 3.1 km west of the Bowdon 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
- DUNHAM MASSEY WwTWCurrent status unknown
United Utilities · River Bollin
- Green Dragon Hotel CSOCurrent status unknown
United Utilities · River Bollin
- Oughtrington Lane CSOCurrent status unknown
United Utilities · Bridgewater Canal
- HIGH LEGH WwTWCurrent status unknown
United Utilities · Agden Brook
Questions about Dunham Massey Outfall SSO
- Who operates Dunham Massey Outfall SSO?
- United Utilities is the operator named in the annual record. The permit reference is 01TRA0079.
- Where does Dunham Massey Outfall SSO discharge?
- The source names River Bollin via SWS as the receiving water. This does not show how far a discharge travelled.
- How many times did Dunham Massey Outfall SSO spill in 2025?
- The 2025 return records 43 counted spill events and 166.8 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 95.4% of the reporting period, so the annual figures cover most of the year. They still do not measure discharge volume.
- Is Dunham Massey Outfall SSO 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 Dunham Massey Outfall SSO?
- 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 Dunham Massey Outfall SSO compare with other overflows?
- Dunham Massey Outfall SSO recorded 43 spills in 2025. That is more than 84% of the 14,239 overflows in England with a reported figure, and ranks 2,156th nationally. Among United Utilities overflows it ranks 534th of 2,270; the median United Utilities overflow recorded 15 spills. On the Bollin (Ashley Mill to Manchester Ship Canal) waterbody it ranks 3rd of 7. 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.