What it is
Escherichia coli, usually shortened to E. coli, is a bacterium that lives in the intestines of humans and warm-blooded animals. It does not survive long outside the body, so finding it in water means contamination is recent. Results are reported as the number of colony-forming units in 100 ml, and the only acceptable result is none.
Where it comes from
E. coli reaches a water supply from sewage or animal waste: a leaking septic tank or soakaway, livestock around a spring or well, slurry spread on nearby land, surface water getting into a poorly sealed wellhead, or a break in a pipe. Heavy rain often carries it in, so a supply that was fine in summer can fail in winter.
Why it matters
Most strains of E. coli are harmless in themselves, but their presence shows that other organisms from faeces, including viruses and parasites that cause stomach upsets, may be present too. Some strains cause serious illness directly. Water containing E. coli should be boiled before drinking, cooking or brushing teeth until a retest shows it is clear. Children, older people and anyone with a weakened immune system are most at risk.
What can be done about it
First, find and fix the route in: a Pozzani engineer will inspect the source, the wellhead or spring chamber and the storage tank. The supply is then disinfected and flushed. For lasting protection, an ultraviolet (UV) disinfection unit after suitable filtration is the standard treatment for private supplies, as it kills bacteria without adding chemicals. A retest confirms the water is clear before you stop boiling.
Information last reviewed 5 October 2026 by Pozzani Pure Water.