Horley (Surrey) STW
Storm overflow operated by Thames Water. The source names Mole as the receiving water.
- 59
- Spills in 2025
- 835.8
- Recorded hours
- 86.5%
- Monitor operation
- 3
- Years listed
Checking the latest monitor report…
How it compares in 2025
Horley (Surrey) STW recorded 59 spills in 2025. That is more than 91% of the 14,239 overflows in England with a reported figure, and ranks 1,145th nationally. Among Thames Water overflows it ranks 30th of 579; the median Thames Water overflow recorded 6 spills. On the Mole - Horley to Dorking waterbody it ranks 2nd of 7.
The monitor worked for 86.5% of 2025, so this count may be low and its rank may understate activity.
| Group | Rank by spills | Median spills | Median hours |
|---|---|---|---|
| This outlet | – | 59 | 835.8 |
| England | 1,145th of 14,239 | 11 | 22.3 |
| Thames Water | 30th of 579 | 6 | 20.9 |
| Mole - Horley to Dorking | 2nd of 7 | 26 | 218 |
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 | 59 | 835.8 hours | 86.5%Low coverage | Official data |
| 2024 | 91 | 1,444.3 hours | 99.7% | Official data |
| 2023 | 80 | 1,240 hours | 97.7% | 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
- Thames Water
- Outlet type
- Storm tank at a wastewater treatment works
- Permit
- CTCR.1779
- Activity reference
- 1 activity on permit
- Grid reference
- TQ2679043590
- Waterbody ID
- GB106039017625Official 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 Horley (Reigate and Banstead) 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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Questions about Horley (Surrey) STW
- Who operates Horley (Surrey) STW?
- Thames Water is the operator named in the annual record. The permit reference is CTCR.1779.
- Where does Horley (Surrey) STW discharge?
- The source names Mole as the receiving water. This does not show how far a discharge travelled.
- How many times did Horley (Surrey) STW spill in 2025?
- The 2025 return records 59 counted spill events and 835.8 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 86.5% of the reporting period. Below 90%, some events can be missed, so the count and hours may understate activity.
- Is Horley (Surrey) 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 Horley (Surrey) 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 Horley (Surrey) STW compare with other overflows?
- Horley (Surrey) STW recorded 59 spills in 2025. That is more than 91% of the 14,239 overflows in England with a reported figure, and ranks 1,145th nationally. Among Thames Water overflows it ranks 30th of 579; the median Thames Water overflow recorded 6 spills. On the Mole - Horley to Dorking waterbody it ranks 2nd 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.