Where It Comes From
Human and animal feces, sewage leaks, failing septic systems, manure runoff, and storm or floodwater reaching wells or aquifers [1][2].
How You Are Exposed
Drinking from private wells or small groundwater systems, or swimming where sewage overflows have occurred [1][3].
Why It Matters
Finding coliphage means a higher chance that disease-causing enteric viruses (like norovirus) are present; under EPA’s GWR, detecting fecal indicators at the source triggers actions to protect users [1][2].
Who Is at Risk
Infants, young children, older adults, pregnant people, those with weakened immune systems, and users of private wells or systems with septic problems [1][3].
How to Lower Your Exposure
Maintain and test wells regularly; fix septic issues; avoid using water that may be contaminated; during advisories, boil water for 1 minute (3 minutes above 6,500 ft); consider certified virus treatment (e.g., UV disinfection or reverse osmosis) or use bottled water until resolved [3][4].
References
- [1]US EPA. Ground Water Rule. https://www.epa.gov/dwreginfo/ground-water-rule
- [2]WHO. Guidelines for Drinking-water Quality, 4th ed. (2022 update). https://www.who.int/publications/i/item/9789240045064
- [3]CDC. Private Wells – Testing & Maintenance. https://www.cdc.gov/healthy-water/drinking/private/wells/
- [4]CDC. Boil Water Advisory. https://www.cdc.gov/healthywater/emergency/drinking/drinking-water-advisories/boil-water-advisory.html