Where It Comes From
Naturally present in soil and water; grow on pipe surfaces and household plumbing, especially with low disinfectant or stagnation. [1][2]
How You Are Exposed
Drinking tap water; breathing fine droplets from showers, humidifiers, and similar devices. [1][3]
Why It Matters
HPC itself is usually not a direct health risk, but elevated counts can affect taste/odor, complicate lab tests, and flag system problems; many utilities track HPC (e.g., operational target ≤500 CFU/mL). [1][2]
Who Is at Risk
People with weakened immune systems, older adults, infants, and those in healthcare settings. [1][3]
How to Lower Your Exposure
Run taps after periods of nonuse; clean aerators/showerheads; maintain and disinfect humidifiers; follow device instructions; use certified point‑of‑use filters or boil water during advisories; keep home hot‑water systems properly maintained. [1][3]
References
- [1]WHO. Heterotrophic Plate Counts and Drinking-water Safety. World Health Organization, 2003.
- [2]EPA. National Primary Drinking Water Regulations – Microorganisms (Heterotrophic Plate Count). US Environmental Protection Agency, epa.gov.
- [3]CDC. Reduce Risk from Waterborne Germs at Home (drinking water, devices, and maintenance). Centers for Disease Control and Prevention, cdc.gov.