Where It Comes From
Human and animal feces entering water via sewage overflows, failing septic systems, agricultural runoff, stormwater, and wildlife [1][2].
How You Are Exposed
Drinking or using contaminated water; swimming; eating raw/undercooked shellfish; floodwater contact; produce irrigated with contaminated water [1][2][3].
Why It Matters
High levels signal pathogens that can cause diarrhea, vomiting, ear/skin infections; may trigger beach closures or boil-water advisories [1][2].
Who Is at Risk
Young children, older adults, pregnant people, and those with weakened immune systems [2][3].
How to Lower Your Exposure
Heed advisories; avoid swimming after heavy rain; disinfect drinking water (boil 1 minute, appropriate filtration/UV); maintain wells and septic systems; wash hands; cook shellfish thoroughly [2][3][1].
References
- [1]U.S. EPA. Recreational Water Quality Criteria (2012).
- [2]CDC. E. coli and Drinking Water from Private Wells (accessed 2025).
- [3]WHO. Guidelines for Drinking-water Quality, 4th ed. (2017/2022 updates).