Wales

E. coli is a bacteria found in animal and human poop. If it shows up in bathing water, it's usually from land run-off or sewage. Higher levels mean swimmers could be at risk of getting sick. The UK Environment Agency classifies inland bathing waters as Excellent, Good, Sufficient, or Poor, based on two to four years of testing rather than a single sample. So one reading can't tell you how a bathing water is officially classified, but it can show you how today's water compares to their thresholds. We've used 1,000 CFU/100 mL as the cut-off, which is the upper limit of the Good classification (if over 95% samples are under 1,000 CFU/100mL) and the most common interpretation for single samples.

pH measures how acidic or alkaline water is, and it affects the toxicity of many substances in the water as well as the ability of fish and invertebrates to breathe, reproduce, and survive. Outside the acceptable range, fish experience increasing physiological stress, and sensitive invertebrates like mayflies can be affected at levels that seem only mildly acidic. The UK's Water Framework Directive sets a freshwater pH range of 6 to 9 to protect aquatic life.