Heterotrophic Plate Count

Heterotrophic Plate Count

Heterotrophic Plate Count


The Heterotrophic Plate Count (HPC) is used to count total bacteria in water under certain growth conditions (media and temperature).

HPC can be used to monitor changes in the bacteriological quality of finished water throughout a distribution system, thus giving an indication of the effectiveness of chlorination or other disinfection in the system, as well as the possible existence of cross-connections, sediment accumulations and other problems within the distribution lines.

HPC is also used to evaluate the effectiveness of biocides in cooling water systems. Types of water that may be tested include potable water, swimming pools, spas, cooling towers, and reclaimed water.

Test Method

  • Enzyme Substrate Method, incubation 35°C ± 0.5°C for 2–3 days in humidified air.
  • Standard Methods for the Examination of Water and Wastewater: Method 9215E.
  • Measure of uncertainty available upon request.

Turn Around Time
2–7 days

Test Code

Sample Transport
See Sampling and Shipping page for instructions.

Accreditations and Proficiency
See Accreditations and Proficiency page for information on our accreditations and Legionella testing proficiency programs.