Dorchester STW
Storm overflow operated by Thames Water. The source names Thame as the receiving water.
- 15
- Spills in 2025
- 121
- Recorded hours
- 99.9%
- Monitor operation
- 3
- Years listed
The reported spill count was 48 lower than in 2024. This compares event counts, not discharge volume.
Checking the latest monitor report…
How it compares in 2025
Dorchester STW recorded 15 spills in 2025. That is more than 56% of the 14,239 overflows in England with a reported figure, and ranks 5,981st nationally. Among Thames Water overflows it ranks 193rd of 579; the median Thames Water overflow recorded 6 spills. On the Thame (Scotsgrove Brook to Thames) waterbody it ranks 3rd of 3.
| Group | Rank by spills | Median spills | Median hours |
|---|---|---|---|
| This outlet | – | 15 | 121 |
| England | 5,981st of 14,239 | 11 | 22.3 |
| Thames Water | 193rd of 579 | 6 | 20.9 |
| Thame (Scotsgrove Brook to Thames) | 3rd of 3 | 64 | 1,124.8 |
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 | 15 | 121 hours | 99.9% | Official data |
| 2024 | 63 | 791.3 hours | 99.5% | Official data |
| 2023 | 4 | 17 hours | 99.5% | 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
- Thames Water
- Outlet type
- Inlet storm overflow at a wastewater treatment works
- Permit
- TEMP.2542
- Activity reference
- 1 activity on permit
- Grid reference
- SU5801093700
- Waterbody ID
- GB106039030240Official 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 “Inlet SO at WwTW”: inlet storm overflow at a wastewater treatment works. The overflow is at the inlet of a treatment works, where wastewater enters the 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 0.9 km south of the Dorchester (South Oxfordshire) 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
- Benson STWCurrent status unknown
Thames Water · Howbery Ditch
- Little Milton STWCurrent status unknown
Thames Water · Gainsbridge Brook
- Chalgrove STWCurrent status unknown
Thames Water · Warpsgrave Ditch
- Watlington STWCurrent status unknown
Thames Water · Pyrton Stream
Questions about Dorchester STW
- Who operates Dorchester STW?
- Thames Water is the operator named in the annual record. The permit reference is TEMP.2542.
- Where does Dorchester STW discharge?
- The source names Thame as the receiving water. This does not show how far a discharge travelled.
- How many times did Dorchester STW spill in 2025?
- The 2025 return records 15 counted spill events and 121 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 99.9% of the reporting period, so the annual figures cover most of the year. They still do not measure discharge volume.
- Is Dorchester 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 Dorchester STW?
- The annual return lists the asset type as “Inlet SO at WwTW”, which means inlet storm overflow at a wastewater treatment works. The overflow is at the inlet of a treatment works, where wastewater enters the works.
- How does Dorchester STW compare with other overflows?
- Dorchester STW recorded 15 spills in 2025. That is more than 56% of the 14,239 overflows in England with a reported figure, and ranks 5,981st nationally. Among Thames Water overflows it ranks 193rd of 579; the median Thames Water overflow recorded 6 spills. On the Thame (Scotsgrove Brook to Thames) waterbody it ranks 3rd of 3. 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.