What Total Coliform Rule (TCR) violations actually mean, and why coliform bacteria is an indicator rather than proof of contamination.
Data current as of July 2026
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Coliform bacteria is one of the most common violation types on EPA water quality reports, and also one of the most misunderstood — its presence is a signal to check further, not a confirmed health hazard on its own.
Coliform Bacteria (TCR)
A group of common bacteria used as an indicator that disease-causing organisms could be present, not necessarily that they are. Its presence prompts follow-up testing for actual pathogens.
The Total Coliform Rule (TCR) requires utilities to test for this indicator regularly. A violation means the indicator was found (or testing/reporting requirements weren't met) — see "Understanding EPA Violation Status" for what the specific status (archived, addressed, unaddressed, resolved) means for whether it's still an active concern.
Filtration
Standard home carbon and RO filters are not certified or designed as a substitute for proper disinfection of bacterial contamination — if a specific pathogen concern is confirmed (not just the coliform indicator), a boil-water notice or point-of-use filter certified for microbiological removal (NSF/ANSI 53 or 58 with a specific bacteria/cyst claim) is the appropriate response, not routine carbon filtration.
Live in this area? Simple Water Heater & Filtration can size a filtration system to whatever's actually on file for your utility.