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Polluted by sewage 705 times in 2025 lasting 5,262 hours
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Donate NowHere are all the reported sewage overflow totals for Caernarfon 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 | Menai Strait | BRYNSCIENCYN STW | 184 | 2,785 | 99.9 |
| Dwr Cymru Welsh Water | River Seiont | CAERNARFON STW | 90 | 1,251 | 99.8 |
| Dwr Cymru Welsh Water | Seiont | CAERNARFON PONT SEIONT PS | 41 | 354 | 99.7 |
| Dwr Cymru Welsh Water | River Seiont | CAERNARFON WWTW INLET PUMP ST 6MM | 83 | 301 | 99.8 |
| Dwr Cymru Welsh Water | Cadnant - Caernarfon | SSO AT MILL LANE CAERNARFON | 87 | 194 | 99.9 |
| Dwr Cymru Welsh Water | Menai Strait | BRYNSCIENCYN PS , , | 13 | 103 | 99.9 |
| Dwr Cymru Welsh Water | River Seiont | Peblig Industrial Estate CSO | 37 | 97 | 98.2 |
| Dwr Cymru Welsh Water | Menai Straits | CROSSVILLE CSO | 67 | 95 | 99.9 |
| Dwr Cymru Welsh Water | Unnamed Watercourse | CAERNARFON MARGARET STREET SSO | 57 | 36 | 98.7 |
| Dwr Cymru Welsh Water | River Seiont | Caernarfon WWTW Inlet Pump ST 6mm SPS | 18 | 28 | 99.8 |
| Dwr Cymru Welsh Water | Cadnant | MIN-Y-NANT CSO | 27 | 14 | 99.7 |
| Dwr Cymru Welsh Water | Menai Straits | BALACLAVA ROAD SEWAGE PUMPING ST | 1 | 0 | 99.8 |
| Dwr Cymru Welsh Water | River Siont | ANGLESEY ARMS PUMPING STATION | 0 | 0 | 100 |
| Dwr Cymru Welsh Water | Menai Straits | CAERNARFON BANK QUAY PS | 0 | 0 | 99.9 |
| Dwr Cymru Welsh Water | Menai Strait | WATERLOO PORT SEWAGE PUMPING ST | 0 | 0 | 99.2 |
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