Gladys Avenue Portsmouth CSO - 108434
Storm overflow operated by Southern Water. The source names Portsmouth Harbour as the receiving water.
- 39
- Spills in 2025
- 98.7
- Recorded hours
- 99.7%
- Monitor operation
- 2
- Years listed
The reported spill count was 17 lower than in 2024. This compares event counts, not discharge volume.
Checking the latest monitor report…
How it compares in 2025
Gladys Avenue Portsmouth CSO - 108434 recorded 39 spills in 2025. That is more than 81% of the 14,239 overflows in England with a reported figure, and ranks 2,494th nationally. Among Southern Water overflows it ranks 126th of 975; the median Southern Water overflow recorded 7 spills. On the Portsmouth Harbour waterbody it ranks 2nd of 36.
| Group | Rank by spills | Median spills | Median hours |
|---|---|---|---|
| This outlet | – | 39 | 98.7 |
| England | 2,494th of 14,239 | 11 | 22.3 |
| Southern Water | 126th of 975 | 7 | 17 |
| Portsmouth Harbour | 2nd of 36 | 3 | 1.8 |
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 | 39 | 98.7 hours | 99.7% | Official data |
| 2024 | 56 | 123.9 hours | 99.7% | 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
- Southern Water
- Outlet type
- Storm overflow on the sewer network
- Permit
- W00279
- Activity reference
- Storm
- Grid reference
- SU6407002560
- Waterbody ID
- GB580705140000Official 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 1.3 km south-west of the Portsmouth 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
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- Winstanley Road Portsmouth CSO - 108504Current status unknown
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- North End Avenue Portsmouth CSO - 108773Current status unknown
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Questions about Gladys Avenue Portsmouth CSO - 108434
- Who operates Gladys Avenue Portsmouth CSO - 108434?
- Southern Water is the operator named in the annual record. The permit reference is W00279.
- Where does Gladys Avenue Portsmouth CSO - 108434 discharge?
- The source names Portsmouth Harbour as the receiving water. This does not show how far a discharge travelled.
- How many times did Gladys Avenue Portsmouth CSO - 108434 spill in 2025?
- The 2025 return records 39 counted spill events and 98.7 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 99.7% of the reporting period, so the annual figures cover most of the year. They still do not measure discharge volume.
- Is Gladys Avenue Portsmouth CSO - 108434 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 Gladys Avenue Portsmouth CSO - 108434?
- 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 Gladys Avenue Portsmouth CSO - 108434 compare with other overflows?
- Gladys Avenue Portsmouth CSO - 108434 recorded 39 spills in 2025. That is more than 81% of the 14,239 overflows in England with a reported figure, and ranks 2,494th nationally. Among Southern Water overflows it ranks 126th of 975; the median Southern Water overflow recorded 7 spills. On the Portsmouth Harbour waterbody it ranks 2nd of 36. 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.