Heswall WwTW
Storm overflow operated by Dŵr Cymru Welsh Water. The source names Estuarial Waters of the River Dee as the receiving water.
- 22
- Spills in 2025
- 205.5
- Recorded hours
- 99.4%
- Monitor operation
- 2
- Years listed
The reported spill count was 36 lower than in 2024. This compares event counts, not discharge volume.
We do not have a live report for this outlet. Its annual spill records are shown below.
How it compares in 2025
Heswall WwTW recorded 22 spills in 2025. That is more than 65% of the 14,239 overflows in England with a reported figure, and ranks 4,697th nationally. Among Dŵr Cymru Welsh Water overflows it ranks 52nd of 122; the median Dŵr Cymru Welsh Water overflow recorded 14.5 spills. On the MERSEY MOUTH - transitional waterbody it ranks 12th of 23.
| Group | Rank by spills | Median spills | Median hours |
|---|---|---|---|
| This outlet | – | 22 | 205.5 |
| England | 4,697th of 14,239 | 11 | 22.3 |
| Dŵr Cymru Welsh Water | 52nd of 122 | 14.5 | 29.3 |
| MERSEY MOUTH - transitional | 12th of 23 | 22 | 45.4 |
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 | 22 | 205.5 hours | 99.4% | Official data |
| 2024 | 58 | 715.5 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
- Dŵr Cymru Welsh Water
- Outlet type
- Storm tank at a wastewater treatment works
- Permit
- CG0362601
- Activity reference
- 1
- Grid reference
- SJ2497081795
- Waterbody ID
- GB641211630001Official 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 km south-west of the Heswall 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
- Park West CSO HeswallCurrent status unknown
Dŵr Cymru Welsh Water · River Dee
- Heswall Seabank Rd CSOCurrent status unknown
Dŵr Cymru Welsh Water · River Dee Estuary
- Heswall Gayton Riverbank Road Mh466 NraCurrent status unknown
Dŵr Cymru Welsh Water · Estuarial Waters of the River Dee
- Long Hey Road CSOCurrent status unknown
United Utilities · River Dee (North Wales)
Questions about Heswall WwTW
- Who operates Heswall WwTW?
- Dŵr Cymru Welsh Water is the operator named in the annual record. The permit reference is CG0362601.
- Where does Heswall WwTW discharge?
- The source names Estuarial Waters of the River Dee as the receiving water. This does not show how far a discharge travelled.
- How many times did Heswall WwTW spill in 2025?
- The 2025 return records 22 counted spill events and 205.5 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 99.4% of the reporting period, so the annual figures cover most of the year. They still do not measure discharge volume.
- Is Heswall WwTW discharging right now?
- This record is not matched to a company live feed, so we cannot show a current report. Only the annual figures are available for this outlet.
- 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 Heswall WwTW?
- 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 Heswall WwTW compare with other overflows?
- Heswall WwTW recorded 22 spills in 2025. That is more than 65% of the 14,239 overflows in England with a reported figure, and ranks 4,697th nationally. Among Dŵr Cymru Welsh Water overflows it ranks 52nd of 122; the median Dŵr Cymru Welsh Water overflow recorded 14.5 spills. On the MERSEY MOUTH - transitional waterbody it ranks 12th of 23. 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.