E. coli samples at bathing waters

Every Environment Agency lab sample of E. coli at the inland bathing waters this site covers, with the date each was taken. A historical record of the water at those times, not of the water today. For a bathing water's official rating and today's advice, the Environment Agency's own page comes first; each bathing water here links to it.

What these samples do not tell you

• One sample is the water at one place and time. It says nothing about the water on another day, or later the same day.
• The hindsight estimate is not the forecast the site issued that day. The site's issued forecasts are scored on the Accuracy page.
• A sample the model missed, or a warning with no high sample, does not point to any overflow, water company or other source.

How the hindsight estimate was made

After the samples were taken, the site's model was refitted once for each year, each time leaving out that year's samples, and run for each sample's day on the rain forecast archived for that day and the exposure to spills upstream, replayed for it. Its inputs are the ones the forecast uses: rain, the spills upstream, the season and, for rivers, how wet the soil was. The result is the chance the model gives of the count being over 900 per 100 ml. It was never shown on the site.

• What this page's data holds
• How the forecast works

Sources

Environment Agency bathing water quality data, Open Government Licence v3.0. Samples from the Environment Agency's bathing water quality service, and from its Water Quality Archive for samples the service's copy lacked. Data credits.