Testing by Vanguard Laboratory · Olympia, Washington360-967-7010

Bacteria & microbiology

SM 9221 B: Total coliform counts

Scope SM 9221 B for total coliform counts. Define sample matrix, preparation, reporting limits and project requirements.

Total coliform counts measurement context

Standard Methods 9222 B, membrane filtration: a measured volume is filtered, the membrane is incubated on a selective medium, and typical coliform colonies are counted as colony-forming units (CFU) per 100 mL. Standard Methods 9221 B, multiple-tube fermentation: portions of the sample are incubated in a series of tubes, and the pattern of positive tubes gives a most probable number (MPN) per 100 mL, a statistical estimate. For drinking water, coliform-positive results are checked for fecal coliforms or E. coli by Standard Methods 9221 E1 or F. Fecal coliforms and E. coli. Fecal coliform counts and E. coli counts are separate tests. E. coli is one species within the fecal coliform group, so a fecal coliform count includes E. coli along with other thermotolerant coliforms, while an E. coli count reports E. coli alone. Both are described below.

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 details

Source review: November 8, 2026. The agreed method and project scope govern the testing.

Start with a defined scope

Build a project scope

Tell us the sample, the question and the decision your results need to support.

Build a testing request