E. coli
What is it? E. coli (short for Escherichia coli) is a bacteria that lives in the guts of warm-blooded animals, including humans. Most strains are harmless. We test for it in water because finding it tells us that poop has gotten in recently — from sewage, wildlife like geese and ducks, livestock, pets, or other sources.
Why does it matter? E. coli itself usually won't make you sick, but its presence is a warning sign. Where there's fecal contamination, there can also be other germs — viruses, parasites, and some harmful bacteria — that do cause illness if you swallow the water or swim in it. That's why it's the bacteria most countries use to decide whether water is safe for swimming.
What does it mean? Water quality can change quickly, so beaches, rivers, lakes, and swimming holes need to be tested often. The guidelines for safe E. coli levels come from health studies that tracked how often swimmers got sick — usually with stomach issues like diarrhea — at different levels of contamination. The numbers aren't arbitrary; they're based on real-world risk.
Once you enter your results, we'll colour-code them based on the standards for your region, so you can see at a glance whether your water falls within safe levels.