Cassop STW
Storm overflow operated by Northumbrian Water. The source names Chapman Beck as the receiving water.
- 38
- Spills in 2025
- 140.2
- Recorded hours
- 95.8%
- Monitor operation
- 2
- Years listed
The reported spill count was 15 lower than in 2024. This compares event counts, not discharge volume.
Checking the latest monitor report…
How it compares in 2025
Cassop STW recorded 38 spills in 2025. That is more than 81% of the 14,239 overflows in England with a reported figure, and ranks 2,593rd nationally. Among Northumbrian Water overflows it ranks 230th of 1,559; the median Northumbrian Water overflow recorded 11 spills.
| Group | Rank by spills | Median spills | Median hours |
|---|---|---|---|
| This outlet | – | 38 | 140.2 |
| England | 2,593rd of 14,239 | 11 | 22.3 |
| Northumbrian Water | 230th of 1,559 | 11 | 15.6 |
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 | 38 | 140.2 hours | 95.8% | Official data |
| 2024 | 53 | 363.5 hours | 99.9% | 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
- Northumbrian Water
- Outlet type
- Storm tank at a wastewater treatment works
- Permit
- 243/1016
- Activity reference
- A2
- Grid reference
- NZ3412538365
- Waterbody ID
- GB103024077470Official 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 2.1 km north of the Kelloe reference point in the ONS built-up areas data.
Area and water pages
- Durham area →
- High Pittington area →
- East Rainton area →
- Sherburn (County Durham) area →
- West Rainton area →
- Brandon (County Durham) area →
- Hetton le Hill area →
- Sherburn Hill area →
- Croxdale area →
- Hetton-le-Hole area →
- High Shincliffe area →
- Spennymoor area →
- Easington Lane area →
- Shadforth area →
- Bowburn area →
- Old Durham Beck from Chapman Beck to Wear 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
- Kelloe SSO Manhole No. 18Current status unknown
Northumbrian Water · Coxhoe Beck, Tributary of
- Davey Lamp Ph CSOCurrent status unknown
Northumbrian Water · Coxhoe Beck
- Railway Line CSOCurrent status unknown
Northumbrian Water · Coxhoe Beck
- Workingmen'S Club CSOCurrent status unknown
Northumbrian Water · Coxhoe Beck
Questions about Cassop STW
- Who operates Cassop STW?
- Northumbrian Water is the operator named in the annual record. The permit reference is 243/1016.
- Where does Cassop STW discharge?
- The source names Chapman Beck as the receiving water. This does not show how far a discharge travelled.
- How many times did Cassop STW spill in 2025?
- The 2025 return records 38 counted spill events and 140.2 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 95.8% of the reporting period, so the annual figures cover most of the year. They still do not measure discharge volume.
- Is Cassop STW 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 Cassop STW?
- 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 Cassop STW compare with other overflows?
- Cassop STW recorded 38 spills in 2025. That is more than 81% of the 14,239 overflows in England with a reported figure, and ranks 2,593rd nationally. Among Northumbrian Water overflows it ranks 230th of 1,559; the median Northumbrian Water overflow recorded 11 spills. 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.