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Dwr Cymru Welsh Water storm overflows

2,366 storm overflows · 2,362 with a live status feed · regulated by Natural Resources Wales.

Discharging now
59
of 2,362 overflows reporting live
Spills in 2025
90,370
official, from 2,028 monitored overflows
Hours in 2025
733k
total discharge time, 361 h per overflow
Average per overflow
44.6
spills each in 2025 · -4% on 2024 (46.4)

Discharging now longest-running 15 of 59

From Dwr Cymru Welsh Water's live monitor feed, longest-running first.

Waterston WwTW Storm Overflow Hazelbeach Stream
16 h 30 minsince 29 Sep, 21:00
Talbot Street Maesteg Storm Overflow River Llynfi
13 h 45 minsince 29 Sep, 23:45
Fishguard Slade Sea Discharge Storm Overflow Fishguard Harbour
13 h 30 minsince 30 Sep, 00:00
Llanfynydd WwTW Storm Overflow Afon Sannen
13 h 13 minsince 30 Sep, 00:17
Pontamman Pipe Crossing Storm Overflow River Amman
13 h 0 minsince 30 Sep, 00:30
Penygroes Storm Overflow Afon Lash
12 h 45 minsince 30 Sep, 00:45
Hirwaun Industrial Estate WwTW Storm Overflow Afon Camnant
12 h 45 minsince 30 Sep, 00:45
Peniel Overflow Nant Crychiau
12 h 37 minsince 30 Sep, 00:53
Carmel WwTW Storm Overflow Tributary Of Afon Marlais
12 h 30 minsince 30 Sep, 01:00
Pontyberem WwTW Storm Overflow Gwendraeth Fawr
12 h 30 minsince 30 Sep, 01:00
Trebanos WwTW Storm Overflow River Tawe
12 h 15 minsince 30 Sep, 01:15
Ystradgynlais WwTW Wetland Return Storm Overflow River Tawe
11 h 45 minsince 30 Sep, 01:45
Crosshands WwTW Storm Overflow River Gwili
11 h 34 minsince 30 Sep, 01:56
Salem WwTW Storm Overflow Afon Myddyfi
11 h 32 minsince 30 Sep, 01:58
Afan WwTW Storm Overflow Swansea Bay
11 h 15 minsince 30 Sep, 02:15

Year by year

Spills reported across all of Dwr Cymru Welsh Water's monitored overflows.

20221,826 sites
61,982 spills · 376k h
20231,773 sites
86,256 spills · 654k h
20242,020 sites
93,808 spills · 709k h
20252,028 sites
90,370 spills · 733k h

More overflows were monitored each year (1,826 in 2022, 2,028 in 2025), so part of any rise is more monitors, not only more spilling.

Dŵr Cymru Welsh Water's annual Event Duration Monitoring return to Natural Resources Wales (12/24-hour spill count), as compiled by The Rivers Trust. Overflows with no usable monitor data in a year are left out of it, not counted as zero. A further 119 Welsh Water overflows in England report to the Environment Agency instead: 2,725 spills in 2025, not included above.

Most spills in 2025

The overflows that spilled most often. A red tag means discharging right now.

1
Llanfachraeth WwTW Overflow River Alaw
3665,498 h
2
Cwrtnewydd WwTW Storm Overflow Nant Cledlyn
3634,409 h
3
Spring Street Connahs Quay OverflowNow Wepra Brook
3182,369 h
4
Waterston WwTW Storm OverflowNow Hazelbeach Stream
3142,307 h
5
Cwm Penmachno WwTW Storm Overflow River Machno
3006,880 h
6
Efailnewydd WwTW Storm Overflow Unnamed Tributary Of The Afon Rhyd Hir
2811,145 h
7
Pentrecwrt WwTW Storm Overflow River Teifi
2752,280 h
8
Llanaelhaearn WwTW Overflow Unnamed Watercourse
2592,409 h
9
Capel Curig WwTW Storm Overflow Afon Lliw
2433,034 h
10
Four Crosses WwTW Storm Overflow River Erch
2382,713 h
11
Llangybi WwTW Storm Overflow River Usk
2341,345 h
12
Wolfcastle WwTW Storm Overflow Afon Anghof
2251,987 h
13
Cribyn WwTW Storm Overflow Afon Granell
2092,816 h
14
Llanedi WwTW Storm Overflow River Gwili
2081,238 h
15
Llangybi WwTW Overflow River Erch
2033,943 h
16
Pennant WwTW Storm Overflow Afon Arth
201714 h
17
Bronwydd WwTW Storm Overflow River Gwili
1972,495 h
18
Tanybryn Risca Pontymister Storm Overflow River Ebbw
1963,475 h
19
Pwllmeyric Storm Overflow Mounton Brook
1933,932 h
20
Beddgelert WwTW Storm Overflow River Glaslyn
1932,698 h
21
Bryngwran WwTW Overflow Crigyll
1922,901 h
22
Marloes WwTW Storm Overflow Unnamed Watercourse
1922,310 h
23
Boncath WwTW Storm Overflow Tributary Of Afon Morgenau
1903,409 h
24
Barry Docks Pumped Storm Overflow Barry No, 2 Dock
188220 h
25
Waunfarlais Road Brynmarlais Storm Overflow Afon Marlais
1883,336 h

Rivers and seas it discharges into most

Spills in 2025 from Dwr Cymru Welsh Water's overflows, by receiving water (names grouped approximately).

1
River Teifi 35 overflows
2,56926k h
2
River Cynon 42 overflows
1,81910k h
3
River Tawe 32 overflows
1,63411k h
4
River Taff 45 overflows
1,56610k h
5
Afon Lwyd 44 overflows
1,5639,399 h
6
River Llynfi 27 overflows
1,45211k h
7
River Usk 28 overflows
1,42211k h
8
River Towy 13 overflows
1,29910k h
9
Unnamed Watercourse 32 overflows
1,29112k h
10
River Ebbw 37 overflows
1,27410k h

Concerned about an overflow?

Report pollution you can see to Natural Resources Wales on 0300 065 3000 — they log and investigate incidents. Complaints about a company's service go to the company first.

Complain to Dwr Cymru Welsh Water ↗ Report pollution ↗ All companies & rankings

Live status: © Dŵr Cymru Welsh Water, from its Storm Overflow Map. Annual spill figures: Environment Agency Event Duration Monitoring return, © Environment Agency copyright and/or database right, Open Government Licence (OGL) v3.0. Annual figures: The Rivers Trust EDM compilation, © Dŵr Cymru/Welsh Water, Open Government Licence. FloodRadar republishes the monitors' status and the published figures; it does not measure discharges itself, and a monitor reports a discharge, not its volume or its cause.