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Polluted by sewage 857 times in 2025 lasting 6,011 hours
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Donate NowHere 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 |
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.
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Get in touch if you have queries or want to discuss our data.
press [at] top-of-the-poops.org