Caerdydd

Polluted by sewage 857 times in 2025 lasting 6,011 hours

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Totals for Caerdydd in 2025

29 Sites polluted by Dwr Cymru Welsh Water

857 sewage dumps

6,011 hours duration

Sewage pollution map of Caerdydd: 6,011 hours in 2025

That's 8.35 months. On average 2.3 times a day

Change Over Time

Constituency for Caerdydd

Nearby Constituencies

Waterways in Caerdydd

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Pollution Summary 2025

Here are all the reported sewage overflow totals for Caerdydd 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 place 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	Severn Estuary	Kimberley Road CSO	117	1,906	98.5
Dwr Cymru Welsh Water	River Taff	Tongwynlais CSO	69	1,222	99.9
Dwr Cymru Welsh Water	Unknown	St Fagans STW	81	809	99.9
Dwr Cymru Welsh Water	River Rhymney	Storm Water Overflow at Began, St Mellons	93	412	96.7
Dwr Cymru Welsh Water	Severn Estuary	CARDIFF CENTRAL SPS TREMORFA	84	384	96.8
Dwr Cymru Welsh Water	River Rhymney	Ball Lane CSO	45	280	99.9
Dwr Cymru Welsh Water	Severn Estuary	PENARTH HEAD SEWAGE PUMPING STATION	51	211	99.9
Dwr Cymru Welsh Water	River Taff	Ynys Bridge CSO	32	155	98.6
Dwr Cymru Welsh Water	Severn Estuary	Settled Storm Overflow at Cardiff Eastern District Pumping Station	41	144	99.8
Dwr Cymru Welsh Water	Severn Estuary	Penarth Marina SPS	8	90	99.5
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	Cardiff Bay	Grangetown SPS	17	57	99.9
Dwr Cymru Welsh Water	Nant-Y-Wedal	HEATHWOOD ROAD CSO, HEATHWOOD JUNCTION	27	27	92.8
Dwr Cymru Welsh Water	Rhydwaedlyd Brook	Caedelyn Park Boundary CSO	26	26	99.8
Dwr Cymru Welsh Water	Rhymney River	Began Road CSO	10	24	99.5
Dwr Cymru Welsh Water	River Taff Via Culverted Watercourse	ABERPORTH RD CSO	9	17	91.9
Dwr Cymru Welsh Water	River Ely	Penarth Llandough Moors Cardiff CSO, Cardiff	16	16	99.9
Dwr Cymru Welsh Water	River Rhymney	Fishponds Road No22 CSO, Llanrumey	10	14	99.9
Dwr Cymru Welsh Water	River Taff	Cardiff Wood St/Havelock St Jn CSO	13	13	99.6
Dwr Cymru Welsh Water	Taff	Bottom of Westbourne Crescent CSO, Cardiff	13	8	99.6
Dwr Cymru Welsh Water	River Rhymney	Rumney Hill CSO	4	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	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 Rhymney	CSO at Bridge Road, St Mellons, Cardiff	1	0	97.2
Dwr Cymru Welsh Water	Rhymney River	Hartland Road PS	0	0	99.9
Dwr Cymru Welsh Water	Roath Brook	Kimberly Road CSO	0	0	99.9
Dwr Cymru Welsh Water	Cardiff Bay	Curran SPS	0	0	97.1

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

Annual figures up to and including 2025 come from official water company returns. The 2026 figure is our own estimate, derived continuously from the companies' live data feeds.

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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