How to explore historical Swimfo bathing-water data
Swimfo is the Environment Agency's service for finding designated bathing waters in England. TidalWaiv is an independent way to explore the Agency's historical sampling data and classifications, with charts, rolling averages and downloads.
Where can I find historical Swimfo data?
The Environment Agency publishes historical bathing-water data through its Bathing Water Quality data service. TidalWaiv uses this published data to make changes over time easier to explore.
Choose a bathing water to see its available sampling period, annual classification history and interactive charts. The period available varies by location.
How do I read the history?
Annual classifications describe water quality over an assessment period. Individual bacterial samples can vary widely; the charts use a logarithmic scale and four-year rolling geometric means to help explore longer-term patterns.
Historical estimates are labelled separately from official Environment Agency assessments. Changes in indicators and laboratory methods also affect comparisons. Read our existing methodology for the calculation details.
Does historical water quality tell me whether to swim today?
Historical trends and annual classifications do not describe conditions at this moment. Check Swimfo's current bathing-water advice and local notices before deciding whether to swim.
Can I download the results?
Open a location's interactive analysis to download its sample history and classification data. These exports are useful for exploring your local bathing water and checking the values behind the charts.