Top of the Poops | Constituency Sewage Map - 2025 Data| Cardiff South and Penarth

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You're looking at the totals that we have calculated for sewage in Cardiff South and Penarth for 2025. It is an estimate, based on very poor quality live data from the Water Companies. This may not align with the 'official' reported sewage values from the water companies, which is reported in April following then end of the year - so 2025 numbers are reported in April 2026.

What's a potential overflow? If the CSO goes 'Offline' while its Overflowing, we don't know if it stopped overflowing until we get a 'Stop' event.

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Constituencies near Cardiff South and Penarth

Company	Site Name	Receiving Waterway	Overflow Days	Total Duration (hours)	Offline/Potential Pollution
Dwr Cymru Welsh Water	Cardiff Central Storm Overflow	Severn Estuary	61	277h 23m	-
Dwr Cymru Welsh Water	Stonylands Storm Overflow	Sully Brook	29	257h 49m	-
Dwr Cymru Welsh Water	Penarth Head Storm Overflow	Severn Estuary	39	167h 56m	-
Dwr Cymru Welsh Water	Cardiff Eastern Short Sea Outfall Storm Overflow	Severn Estuary	30	119h 43m	-
Dwr Cymru Welsh Water	Cardiff Eastern Long Sea Outfall Storm Overflow	Severn Estuary	30	119h 43m	-
Dwr Cymru Welsh Water	Cog Moors WwTW Storm Overflow	Coastal Waters - Lavernock Point	17	110h 34m	-
Dwr Cymru Welsh Water	Penarth Kymin Storm Overflow	Bristol Channel	36	103h 54m	-
Dwr Cymru Welsh Water	Penarth Marina Storm Overflow	Severn Estuary	6	82h 53m	-
Dwr Cymru Welsh Water	Brockhill Rise Storm Overflow	Bristol Channel	28	81h 41m	-
Dwr Cymru Welsh Water	Cardiff Western District Storm Overflow	River Ely	12	81h 27m	-
Dwr Cymru Welsh Water	Sully Moors Road Storm Overflow	Tributary of Sully Brook	13	37h 45m	-
Dwr Cymru Welsh Water	St Cadoc's Avenue Dinas Powys Storm Overflow	Cadoxton River	8	34h 27m	-
Dwr Cymru Welsh Water	Grangetown Storm Overflow	River Taff	9	31h 16m	-
Dwr Cymru Welsh Water	Penarth Road Storm Overflow	River Ely	9	16h 46m	-
Dwr Cymru Welsh Water	Havelock Street Cardiff Storm Overflow	River Taff	9	11h 21m	-
Dwr Cymru Welsh Water	Maple Road Storm Overflow	Culvert to a Tributary of Sully Brook	5	8h 38m	-
Dwr Cymru Welsh Water	Cogan Flooding Relief Storm Overflow	River Ely via Cowslip	1	6h 30m	-
Dwr Cymru Welsh Water	Cornerswell Road Penarth Storm Overflow	The Sully Brook	5	5h 59m	-
Dwr Cymru Welsh Water	Park Street Cardiff Storm Overflow	River Taff	4	4h 43m	-
Dwr Cymru Welsh Water	Ocean Park Storm Overflow	Severn Estuary	2	2h 45m	-
Dwr Cymru Welsh Water	Penarth Cogan Storm Overflow	River Ely Estuary	5	2h	-
Dwr Cymru Welsh Water	Countess Place Penarth Overflow	The Sully Brook	3	1h 1m	-
Dwr Cymru Welsh Water	Harrowby Street Storm Overflow	River Taff Estuary	1	0h 15m	-
Dwr Cymru Welsh Water	Unknown	Unknown	0	0h	-
Dwr Cymru Welsh Water	Argae Lane Storm Overflow	Culvert Leading to Coldbrook	0	0h	-

Company

Site Name

Receiving Waterway

Overflow Days

Total Duration (hours)

Offline/Potential Pollution

Dwr Cymru Welsh Water

Cardiff Central Storm Overflow

Severn Estuary

277h 23m

Dwr Cymru Welsh Water

Stonylands Storm Overflow