Watch House Bay
Caution
This spot's annual water-quality classification is Poor. Bathing isn't recommended.
Checked against Natural Resources Wales · data last changed 2 months ago.
Sea conditions
Water temperature
17.3°C
Cool — comfortable for a shorter swim
Wave height
0.5 m
Significant wave height offshore; inshore conditions vary.
Tide
Going out
- Low water around UTC
- High water around UTC
Modelled values, not measurements — coastal water often differs from the open-sea model, and tide times are approximate to within about half an hour. Use official tide tables for anything that depends on precise timing.
This spot’s record
Watch House Bay is in the Vale of Glamorgan, about 13 km from Cardiff. Watch House Bay was rated Poor in 2025 by Natural Resources Wales. Its previous classifications were Sufficient in 2024 and Poor in 2023, so the rating here has moved rather than held. Across the 12 most recent samples published by Natural Resources Wales, E. coli counts ranged from 10 to 2,700 per 100 ml. The highest was taken on 21 July 2026. A classification is calculated from percentiles across four seasons, so no single reading decides how this water is rated.
Recent sample results
The last 12 bacterial samples published by Natural Resources Wales, most recent on the right. Counts are per 100 ml of water.
Dashed line: 500 E. coli per 100 ml, the Bathing Water Directive guide value for coastal / transitional waters.
| Date | E. coli | Enterococci | Assessment |
|---|---|---|---|
| 14 Sept | 10 | 36 | — |
| 7 Sept | 18 | 27 | — |
| 30 Aug | 73 | 118 | — |
| 17 Aug | 10 | 10 | — |
| 14 Aug | 470 | 250 | — |
| 4 Aug | 10 | 82 | — |
A bathing water's official classification is calculated from percentiles across four bathing seasons, not from any single sample — so one high reading doesn't mean a spot is unsafe, and one low reading doesn't mean it's clean today.
Quality over the last 3 years
- Poor2023
- Sufficient2024
- Poor2025
This water's rating has varied over the last 3 years.
Official water quality
Classified Poor in 2025.
Official bathing-water profileCommon questions
- Can you swim at Watch House Bay right now?
- Watch House Bay is currently marked "Caution". This spot's annual water-quality classification is Poor. Bathing isn't recommended. This reflects the latest data published by Natural Resources Wales. Conditions change quickly — always assess the water yourself before entering.
- What is the water quality like at Watch House Bay?
- Natural Resources Wales classified Watch House Bay as Poor in 2025. Classifications are a rolling assessment of bacterial samples taken over four bathing seasons, measured against E. coli and intestinal enterococci limits set by the EU Bathing Water Directive.
- Is there a swimming ban or warning at Watch House Bay?
- There are no active bathing restrictions published by Natural Resources Wales for Watch House Bay. That is not a guarantee of safety — assess conditions yourself.
This spot is also in
Get told when this changes
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Nearby swimming spots
See all swimming spots near Cardiff — about 13 km away.