Top of the Poops | Senedd Constituency Sewage Map | Caerdydd Penarth

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Totals for Caerdydd Penarth in 2025

35 Sites polluted by Dwr Cymru Welsh Water

1,089 sewage dumps

6,377 hours duration

That's 8.86 months. On average 3 times a day

Change Over Time

Senedd Constituencies near Caerdydd Penarth

Westminster Constituencies within Caerdydd Penarth

To see live data by overflow, go to the Westminster Constituency, then 'live data'

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Pollution Summary 2025

Here are all the reported sewage overflow totals for Caerdydd Penarth in 2025. Sometimes sewage can be being dumped for months at a time.

Reporting refers to how much of the time the monitoring was active. In this constituency all the declared CSO Combined Sewage Overflow - a device that, when operating, pours combined rainwater & sewage into a waterway s appeared to have monitoring enabled for more than 50% of the year

Company	Waterway	Site	Sewage Dumps	Duration (Hours)	Reporting %
Dwr Cymru Welsh Water	Nant Clun	RHIWSAESON STW RHIWSAESON LLANTRI	179	1,254	99.9
Dwr Cymru Welsh Water	Nant Glaswg	CREIGIAU SEWAGE TREATMENT WORKS HOE	72	1,219	99.9
Dwr Cymru Welsh Water	Unknown	St Fagans STW	81	809	99.9
Dwr Cymru Welsh Water	Nant Coslech	Groesfan SPS	71	644	99.8
Dwr Cymru Welsh Water	Severn Estuary	CARDIFF CENTRAL SPS TREMORFA	84	384	96.8
Dwr Cymru Welsh Water	Nant Dowlais	RHYDLAFAR STW ST FAGANS CARDIFF	87	337	99.9
Dwr Cymru Welsh Water	Sully Brook	CSO and EO at Penarth Stonylands Pumping Station, Penarth	34	320	99.5
Dwr Cymru Welsh Water	Severn Estuary	PENARTH HEAD SEWAGE PUMPING STATION	51	211	99.9
Dwr Cymru Welsh Water	Severn Estuary	Settled Storm Overflow at Cardiff Eastern District Pumping Station	41	144	99.8
Dwr Cymru Welsh Water	Coastal Waters Off Lavernock P	COG MOORS STW CDIFF RD DINAS POWYS	15	110	99.9
Dwr Cymru Welsh Water	River Ely	Miskin Sewage Pumping Station Miskin	19	92	99.9
Dwr Cymru Welsh Water	Severn Estuary	Penarth Marina SPS	8	90	99.5
Dwr Cymru Welsh Water	Severn Estuary	BROCKHILL RISE & LAVERNOCK RD SSO'S	29	84	91.9
Dwr Cymru Welsh Water	River Ely	CSO at TRELAI PARK STORM SEWAGE PS	31	81	99.9
Dwr Cymru Welsh Water	River Ely	Penarth Road WDPS	14	81	99.8
Dwr Cymru Welsh Water	Nant Henstaff	CREIGIAU PS	32	79	99.9
Dwr Cymru Welsh Water	River Clun	RHIWSAESON STW RHIWSAESON LLANTRI Settled Storm	9	79	100
Dwr Cymru Welsh Water	Severn Estuary	KYMIN PS PENARTH CARDIFF ,	40	78	99.4
Dwr Cymru Welsh Water	Cardiff Bay	Grangetown SPS	17	57	99.9
Dwr Cymru Welsh Water	Sully Brook	Sully Moors Road SPS	21	45	99.9
Dwr Cymru Welsh Water	Severn Estuary	CARDIFF EAST DISTRICT LONG OUTFALL	41	41	99.8
Dwr Cymru Welsh Water	R Cadoxton	ST CADOCS AVENUE CSO	13	40	99.5
Dwr Cymru Welsh Water	River Ely	Brynsadler Pumping Station Clun Ely	10	22	99.9
Dwr Cymru Welsh Water	River Ely	Penarth Llandough Moors Cardiff CSO, Cardiff	16	16	99.9
Dwr Cymru Welsh Water	River Taff	Cardiff Wood St/Havelock St Jn CSO	13	13	99.6
Dwr Cymru Welsh Water	River Ely	Danybryn SPS	9	7	99.9
Dwr Cymru Welsh Water	River Ely	Cogan Storm Tank Cogan Penarth	1	5	100
Dwr Cymru Welsh Water	River Ely	Ely Mill Rd/Muston Rd CSO, Cardiff	14	5	99.9
Dwr Cymru Welsh Water	River Taff	Park Street PS	6	4	99.9
Dwr Cymru Welsh Water	River Taff Estuary	Harrowby Street PS	7	4	91.4
Dwr Cymru Welsh Water	Sully Brook	A Combined Sewer Overflow Rear Of	5	4	100
Dwr Cymru Welsh Water	River Ely Estuary	Cogan SPS	8	3	99.5
Dwr Cymru Welsh Water	Severn Estuary	OCEAN PARK PS TREMORFA FORESHORE RO	2	2	99.9
Dwr Cymru Welsh Water	River Ely	CSO at Cardiff Ely Plymouth Rd No 108	8	2	99.6
Dwr Cymru Welsh Water	River Ely	YNYSDDU PUMPING STATION PONTYCLUN	1	0	99.6
Dwr Cymru Welsh Water	Coldbrook	ARGAE LANE CSO ARGAE LANE BARRY	0	0	99.8
Dwr Cymru Welsh Water	Cardiff Bay	Curran SPS	0	0	97.1
Dwr Cymru Welsh Water	River Ely	Fairview SPS	0	0	98.7
Dwr Cymru Welsh Water	River Ely	MAES YR FELIN PUMPING STATION	0	0	99.9
Dwr Cymru Welsh Water	River Ely	RHYDYNANT PS (ADJ TO 49) PONTYCLUN	0	0	99.9

Data Sources & Accuracy

EDM (Event Duration Monitoring) data and Consented Discharges to Controlled Waters with Conditions from Environment Agency & Data Map Wales, and Scottish Water

Experimental derived data from Thames Water API, Some data may be missing or inaccurate. Live sewage data from Stream Water API

Uses Environment Agency rainfall data from the real-time data API (Beta) - Rainfall data is delayed by up to two days.

This website is intended to provide an accurate representation of the Environment Agency data. The data is hard to use, and thus some errors may have been made. If you find something that is incorrect, please raise an issue at the GitHub issues page and we'll endeavour to fix it quickly.

This project is not associated, approved or endorsed by any of the companies whose logos you see here.

Analysing sewage pollution by the Water Industry

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© 2020-2025 Top-Of-The-Poops CC-BY-SA 4.0,
© Openstreetmap contributors, Contains OS data © Crown copyright and database right 2021-2025,
Contains Water UK National Storm Overflow Hub Data CC-BY-SA 4.0 and analysis © 2025 Top-Of-The-Poops

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