E. coli

Category: microbiological

Written by WaterFilterMatch Editorial TeamApril 2026

EPA MCL

0 presence/absence

Status

EPA Regulated

NSF Standard

NSF/ANSI 55 (UV Class A), NSF/ANSI 58

Health Effects

Indicates fecal contamination and potential presence of dangerous pathogens. Certain strains (e.g., O157:H7) can cause severe gastrointestinal illness, bloody diarrhea, kidney failure, and death. Particularly dangerous for children, elderly, and immunocompromised individuals.

Source: EPA National Primary Drinking Water Regulations

Where It Comes From

Human and animal fecal waste. Presence in drinking water indicates a serious treatment failure or direct contamination from sewage or animal waste.

Where It's Commonly Found

Surface water supplies, systems with treatment failures, wells near septic systems or animal operations. Any E. coli detection in a public water system is a serious violation.

Regulated under the 2013 RTCR with an MCL requiring zero detection. Any E. coli-positive sample triggers Tier 1 public notification (24 hours) and immediate corrective action.