What it is
Enterococci are bacteria from the intestines of humans and animals. Like E. coli they are used to show that faecal contamination has reached the water, but they survive longer in the environment, so they can reveal contamination that happened some time ago or that E. coli alone has missed.
Where it comes from
The sources are the same as for E. coli: sewage, septic systems, livestock and slurry, reaching the supply through an unprotected source, a damaged tank or pipework, or after heavy rain.
Why it matters
Finding enterococci means organisms that cause stomach and intestinal illness may be present. The water should be boiled before drinking, cooking or brushing teeth until a retest is clear.
What can be done about it
As for E. coli: find and close the route in, disinfect and flush the system, and fit UV disinfection after filtration for lasting protection. Because enterococci are more persistent, the engineer will pay particular attention to the storage tank and any dead legs in the pipework.
Information last reviewed 5 October 2026 by Pozzani Pure Water.