Targeted testing of heterotrophic bacteria via heterotrophic plate count (HPC). Note: one HPC result is hard to interpret alone, but repeated testing reveals whether your water's bacterial population is stable, increasing (a sign of biofilm or disinfectant breakdown), or changing in response to treatment upgrades. We strongly recommend ordering multiple HPC kits to test your water over time, as one test alone does not indicate safe or unsafe levels. Certified lab testing Fast turnaround at lab (5 business days) Shipping included: Standard shipping to you, Overnight to the lab Expert treatment advice Heterotrophic bacteria are broadly defined as microorganisms that require organic carbon for growth. They include bacteria, yeasts, and molds and this total heterotrophic bacteria plate count (HPC) test is an excellent way to demonstrate a quantified presence or absence of microbial activity in a water supply. This mail-to-lab kit provides all required materials to properly collect and submit a sample for certified laboratory testing. This includes a prepaid shipping label and chain of custody.