Heterotrophic plate count measurement context
Standard Methods 9215: a portion of the sample is mixed into or spread on a general nutrient agar and incubated, and the colonies are counted. Drinking water uses the pour plate method (9215 B); environmental samples can also use the spread plate (9215 C) or membrane filter (9215 D) method. The result, in CFU per mL, is a general count of bacteria that grow on the medium, not a test for a particular organism.
Plan collection and receipt together
Define the organism or indicator, test portion and enumeration or presence/absence question. Use the assigned bottle and collection instructions and coordinate delivery around the method requirements.
Include the complete project requirement
Provide the matrix, target analytes, required method, fraction, units and reporting limits. Include the permit or monitoring instructions where results will support a regulatory submission. Naming this method does not establish blanket compliance eligibility.
Resolve collection before sampling
Use the bottle, preservation and delivery instructions assigned to the agreed scope. Identify each location and collection time, and document any deviation. The final analytical plan must fit the submitted material and its intended use.
Related testing & guidance
Technical & service references
Vanguard service detailsSource review: November 8, 2026. The agreed method and project scope govern the testing.