Storm overflow register · 2025 annual return

Dwr Cymru Welsh Water storm overflows, 2025

Dwr Cymru Welsh Water reported 122 storm overflows in England for 2025. Together they recorded 2,843 spills over 14,525 hours, an average of 23.3 spills per overflow against 20.4 across England. That ranks 7 of 10 companies, where 1 is the fewest spills per overflow. Counting the same overflows in both years, spills were down 46% on 2024.

9 overflows did not spill · 9 spilled more than 60 times · 117 had monitors working for 90% of the year or more · 26 sewage treatment works with overflows

Hours spilling by month, 2025

Hours spilling, all Dwr Cymru Welsh Water overflows, from the start/stop records. Spills running across a month end are split between the months.

All Dwr Cymru Welsh Water storm overflows

Sorted by hours spilling. Open an overflow for its permit, location, reasons for high spills and improvement status.

Overflow	Discharges to	Spills 2025	Hours 2025	Spills vs 2024	Monitor uptime
Chester Parkgate Court SPS Storm discharge at pumping station Company site name Chester Parkgate Court EA ID / permit DCW00022 · CM0191201 Outlet location SJ3994967898 (OS grid reference) · View on Apple Maps WFD catchment Finchetts Gutter (GB111067056930) 2024 spills / hours 2 / 0.8 Long-term average 4.1 spills a year (monitored since 2017) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period Volume & pollution Estimate from 0.8 hours spilling →	Bache Brook	3	0.8	up 50%	96%
Well Street Combined Sewer Overflow Overflow on sewer network Company site name Rear 2 Well St Malpas CSO EA ID / permit DCW00119 · EPRMP3422GZ Outlet location SJ4891747275 (OS grid reference) · View on Apple Maps WFD catchment Bradley Brook (GB111067052230) 2024 spills / hours 1 / 0.3 Long-term average 0.6 spills a year (monitored since 2020) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period Volume & pollution Estimate from 0.8 hours spilling →	Unnamed Watercourse	2	0.8	up 100%	100%
Earle Drive - Parkgate Road CSO Overflow on sewer network Company site name Neston Parkgate Earle Drive/Parkgate Rd EA ID / permit DCW00043 · CM0169901 Outlet location SJ2783477647 (OS grid reference) · View on Apple Maps WFD catchment MERSEY (GB531206908100) Shellfish water Dee (East) 2024 spills / hours – / – Long-term average 0.4 spills a year (monitored since 2015) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period Volume & pollution Estimate from 0.5 hours spilling →	Dee Estuary	2	0.5		95%
Greenfields Drive CSO Overflow on sewer network Company site name Greenfields Drive Little Neston EA ID / permit DCW00054 · CM0170201 Outlet location SJ2905575755 (OS grid reference) · View on Apple Maps WFD catchment MERSEY (GB531206908100) Shellfish water Dee (East) 2024 spills / hours 34 / 330 Long-term average 13.1 spills a year (monitored since 2015) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period Volume & pollution Estimate from 0.5 hours spilling →	Dee Estuary	1	0.5	down 97%	100%
Gayton Parkway CSO Overflow on sewer network Company site name Heswall Gayton Parkway Nra Riverbank Rd EA ID / permit DCW00050 · CM0197201 Outlet location SJ2817480218 (OS grid reference) · View on Apple Maps WFD catchment Tidal Dee (GB531106708200) Shellfish water Dee (East) 2024 spills / hours 11 / 7.5 Long-term average 5.3 spills a year (monitored since 2015) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period Volume & pollution Estimate from 0.5 hours spilling →	Tributary of River Dee	1	0.5	down 91%	100%
Moston Road CSO Overflow on sewer network Company site name Moston Road CSO EA ID / permit DCW00083 · NPSWQD009967 Outlet location SJ4112569675 (OS grid reference) · View on Apple Maps WFD catchment Finchetts Gutter (GB111067056930) 2024 spills / hours 3 / 9.5 Long-term average 2.3 spills a year (monitored since 2017) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period Volume & pollution Estimate from 0.5 hours spilling →	Tributary of River Lugg	1	0.5	down 67%	100%
Lower Lydbrook River Wye CSO Overflow on sewer network Company site name Lower Lydbrook (River Wye) EA ID / permit DCW00071 · AN0015001 Outlet location SO5974416930 (OS grid reference) · View on Apple Maps WFD catchment Wye - conf Walford Bk to Bigsweir Br (GB109055037111) 2024 spills / hours 5 / 2.5 Long-term average 0.7 spills a year (monitored since 2016) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period Volume & pollution Estimate from 0.3 hours spilling →	River Wye	1	0.3	down 80%	100%
Rear of 22 Curzon Park North CSO Overflow on sewer network Company site name Chester Curzon Park North No 22 EA ID / permit DCW00095 · CG0361001 Outlet location SJ3976865536 (OS grid reference) · View on Apple Maps WFD catchment Middle Dee (GB531106708200) 2024 spills / hours 0 / 0.0 Long-term average 0.3 spills a year (monitored since 2017) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period Volume & pollution Estimate from 0.3 hours spilling →	Tributary of the River Dee	1	0.3	up from 0	100%
The Dingle Combined Sewer Overflow Overflow on sewer network Company site name Chester The Dingle Manhole 1202 EA ID / permit DCW00115 · CG0361401 Outlet location SJ4013065215 (OS grid reference) · View on Apple Maps WFD catchment Middle Dee (GB531106708200) 2024 spills / hours 1 / 4.8 Long-term average 4.6 spills a year (monitored since 2017) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period Volume & pollution Estimate from 0.3 hours spilling →	River Dee	1	0.3	no change	99%
Daleside Combined Sewer Overflow Overflow on sewer network Company site name Chester Daleside EA ID / permit DCW00040 · CG0405401 Outlet location SJ4058969734 (OS grid reference) · View on Apple Maps WFD catchment Finchetts Gutter (GB111067056930) 2024 spills / hours 0 / 0.0 Long-term average 0.4 spills a year (monitored since 2017) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period Volume & pollution Estimate from 0.3 hours spilling →	Tributary of Finchetts Gutter	1	0.3	up from 0	100%
Marlston Cum Lache PS SSO Storm discharge at pumping station Company site name Chester Balderton EA ID / permit DCW00077 · CM0075401 Outlet location SJ3744062530 (OS grid reference) · View on Apple Maps WFD catchment Balderton drain (GB111067052150) 2024 spills / hours 45 / 477 Long-term average 18.8 spills a year (monitored since 2019) Monitor below 90% Comms failure / issue · Resolved - Feb Investigation No investigation activity in reporting period Improvement No improvement action in reporting period Volume & pollution Estimate from 0.3 hours spilling →	Tributary of Balderton Brook	1	0.3	down 98%	90%
Sandy Lane Combined Sewer Overflow Overflow on sewer network Company site name Chester Boughton Sandy Lane Car Park EA ID / permit DCW00100 · CM0167201 Outlet location SJ4087365903 (OS grid reference) · View on Apple Maps WFD catchment Dee - Chester Weir to Ceiriog (GB111067057080) 2024 spills / hours 12 / 26 Long-term average 30.2 spills a year (monitored since 2018) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period Volume & pollution Estimate from 0.3 hours spilling →	River Dee	1	0.3	down 92%	100%
Unknown Overflow on sewer network Company site name Hereford Broomy Hill/Belvedere Lane EA ID / permit DCW00005 · Unpermitted Outlet location SO5019239502 (OS grid reference) · View on Apple Maps WFD catchment Wye - Bredwardine Br to Hampton Bishop (GB109055037113) 2024 spills / hours 1 / 0.3 Long-term average 2.4 spills a year (monitored since 2020) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period Volume & pollution Estimate from 0.3 hours spilling →	River Wye	1	0.3	no change	100%
Christleton Old Woman'S Lane CSO Overflow on sewer network Company site name Chester Haslin Crescent EA ID / permit DCW00026 · CG0358801 Outlet location SJ4372165301 (OS grid reference) · View on Apple Maps WFD catchment Finchetts Gutter (GB111067056930) 2024 spills / hours 0 / 0.0 Long-term average 0.3 spills a year (monitored since 2019) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period	Tributary of Caldy Brook	0	0.0	no change	100%
Bache Tanks CSO Overflow on sewer network Company site name Bache Tanks CSO EA ID / permit DCW00013 · CG0359901 Outlet location SJ4028868076 (OS grid reference) · View on Apple Maps WFD catchment Finchetts Gutter (GB111067056930) 2024 spills / hours 1 / 5.8 Long-term average 13.4 spills a year (monitored since 2017) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period	Bache Brook	0	0.0	down 100%	100%
Chester Belgrave Park SPS Storm discharge at pumping station Company site name Chester Belgrave Park EA ID / permit DCW00021 · CG0360901 Outlet location SJ4127664828 (OS grid reference) · View on Apple Maps WFD catchment Dee - Chester Weir to Ceiriog (GB111067057080) 2024 spills / hours 0 / 0.0 Long-term average 0.3 spills a year (monitored since 2017) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period	River Dee	0	0.0	no change	100%
Old Dee Bridge (North Bank) CSO Overflow on sewer network Company site name Chester Hydro Dee Bridge EA ID / permit DCW00088 · CM0125401 Outlet location SJ4065765792 (OS grid reference) · View on Apple Maps WFD catchment Middle Dee (GB531106708200) 2024 spills / hours 0 / 0.0 Long-term average 0.4 spills a year (monitored since 2017) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period	River Dee	0	0.0	no change	100%
Heswall Seabank Road Overflow on sewer network Company site name Heswall Seabank Rd CSO EA ID / permit DCW00059 · CM0173801 Outlet location SJ2608480737 (OS grid reference) · View on Apple Maps WFD catchment MERSEY (GB531206908100) Shellfish water Dee (East) 2024 spills / hours 28 / 229 Long-term average 46.0 spills a year (monitored since 2015) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period	River Dee Estuary	0	0.0	down 100%	99%
Marlston-Cum-Lache Pumping Station Storm discharge at pumping station Company site name Chester Marlston-Cum-Lache EA ID / permit DCW00078 · CM0184801 Outlet location SJ3861263486 (OS grid reference) · View on Apple Maps WFD catchment Balderton drain (GB111067052150) 2024 spills / hours 1 / 0.3 Long-term average 4.0 spills a year (monitored since 2018) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period	Balderton Brook	0	0.0	down 100%	100%
Handbridge Greenbank SPS Storm discharge at pumping station Company site name Chester Greenbank EA ID / permit DCW00057 · CM0185601 Outlet location SJ4117064610 (OS grid reference) · View on Apple Maps WFD catchment Dee - Chester Weir to Ceiriog (GB111067057080) 2024 spills / hours 0 / 0.0 Long-term average 0.0 spills a year (monitored since 2017) Investigation No investigation activity in reporting period Improvement No improvement action in reporting period	River Dee	0	0.0	no change	100%
Gayton Cedarway Pumping Station Storm discharge at pumping station Company site name Cedar Way CSO EA ID / permit DCW00049 · CM0193801 Outlet location SJ2776580257 (OS grid reference) · View on Apple Maps WFD catchment Tidal Dee (GB531106708200) Shellfish water Dee (East) 2024 spills / hours 3 / 0.8 Long-term average 3.2 spills a year (monitored since 2015) Monitor below 90% Comms failure / issue · Resolved - Mar Investigation No investigation activity in reporting period Improvement No improvement action in reporting period	River Dee	0	0.0	down 100%	85%
Unknown Storm discharge at pumping station Company site name Ross-On-Wye Ashburton Trading Estate EA ID / permit DCW00008 · Unpermitted Outlet location SO6074424403 (OS grid reference) · View on Apple Maps WFD catchment Rudhall Bk - source to conf R Wye (GB109055029730) 2024 spills / hours 7 / 7.3 Long-term average 5.4 spills a year (monitored since 2021) Investigation UWWTR investigation completed Improvement No improvement action in reporting period	Rudhall Brook	0	0.0	down 100%	100%

Sewage treatment works

Storm tanks and inlet overflows at each Dwr Cymru Welsh Water sewage works. The figures are 2025 spills.

← All water companies · Contains Environment Agency data licensed under the Open Government Licence v3.0. How to read the data.