Total Coliform Bacteria
EPA Limit (MCL)
No MCL
Health Goal (MCLG)
Zero (0)
No level is considered safe
Unit of Measure
presence/absence
How concentrations are reported
Regulated under the Revised Total Coliform Rule (RTCR). Systems must have no coliform in >5% of monthly samples.
Health Effects
Not harmful themselves but indicate possible presence of harmful pathogens. E. coli indicates recent fecal contamination.
The EPA has set the health goal (MCLG) at zero, meaning no level of exposure is considered risk-free.
How It Gets Into Water
Naturally present in the environment; fecal contamination from human or animal waste
How to Reduce Exposure
- 1Boiling water for 1 minute kills coliform bacteria
- 2NSF/ANSI 55 certified UV systems eliminate bacteria and viruses
- 3Whole-house filtration with 0.5 micron absolute rated filters
- 4If coliform is detected, contact your water utility immediately; this requires prompt action
Always look for NSF/ANSI certified filtration products. Certification means the filter has been independently tested to remove the stated contaminants.
Official EPA Guidance
For authoritative information on Total Coliform Bacteriain drinking water, visit the EPA's official resource page.
View EPA Guidance ↗