How the verdict is decided

The plain answer

Every UK bathing water gets a single verdict. Yes if the water is clean enough today, Caution if recent conditions could degrade quality, and No if there is active pollution or the annual classification is too poor to recommend swimming.

The verdict is decided by software. We do not buy ratings, accept sponsored placements or adjust what the regulator says.

The four signals

1. Annual classification. Every site is graded Excellent, Good, Sufficient or Poor based on four years of bacterial sampling. The regulator publishes the result at the end of each bathing season.
2. Daily pollution-risk forecast. During the bathing season the Environment Agency and Natural Resources Wales publish a same-day forecast that flags raised risk after expected short-term pollution events.
3. Live sewage discharges. The water companies in England and Wales now publish near-real-time data from their storm-overflow monitors. We query the relevant operator for any event that started or finished within ten kilometres of the bathing water in the last 48 hours.
4. Recent rainfall. Heavy rain washes pollution from land into rivers and the sea. We pull rainfall totals from the nearest Environment Agency flood-monitoring station and downgrade the verdict when totals are high.

Coverage

We cover every designated bathing water in the United Kingdom: 464 in England, 114 in Wales, 90 in Scotland and 33 in Northern Ireland. The classifications come directly from the Environment Agency, Natural Resources Wales, SEPA and DAERA.

Live sewage data and the daily risk forecast are presently available for England and Wales. Scottish Water and Northern Ireland Water publish summary data only. For Scotland and Northern Ireland the verdict relies on the regulator's classification, the rainfall signal and any directly observable activity, with a clear note that live storm-overflow data is not yet available.

What we cannot tell you

Bathing water classification measures bacteria. It does not measure chemicals, jellyfish, rip currents or temperature. A Yes verdict means the regulator's water-quality bar is likely cleared and there is no recent sewage discharge in range. It does not mean the water is risk-free. Always check tide times, lifeguard cover and local signs before entering the water.

We update the live signals every five minutes. The regulator updates the daily risk forecast once per day during the bathing season. If a source goes down we degrade gracefully and tell you on the page.

Open data, open methodology

All the data we use is published under the Open Government Licence v3. We attribute the source on every page. There is nothing on this site you could not derive yourself from the same public APIs; we just present it in plain English so you can decide whether to swim.

Get in touch

Spotted a problem? Email hello@isitsafetoswim.com.