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Enumeration of Total & Fecal Coliforms

Multiple Tube Fermentation for the Detection and Enumeration of Total and Fecal Coliforms in Water Samples


PHL Location

Central Laboratory, Amite Laboratory, Lake Charles Laboratory, Shreveport Laboratory

CPT Code



Raw Water

Brief Description of Test

This method describes a Multiple Tube Fermentation for the detection and enumeration of total and fecal coliforms in water samples.

Possible Results

Most Probable Number (MPN) of Fecal Coliforms/100ml

Reference Range


Specimen Type

Surface waters, Wastewater, and Groundwater

Specimen Container(s):

6 oz. Nasco Whirl- Pak bag

Minimum volume accepted:

4 oz.

Collection Instructions

Surface waters, wastewaters, and groundwater samples are collected in sterile, approved containers, containing sodium thiosulfate. The most commonly used collection containers for potable water are sterile disposable 6 oz. Nasco Whirl-Pak bags, each containing a 10 mg sodium tablet. The sampling container must remain closed to maintain sterility until the time that the sample is collected. When the sample is collected, ample air space (at 1 inch) must be left at the top of the container to facilitate mixing of the sample by shaking. When using the 6 oz. Nasco bag, the bag should be filled to the 4 oz. fill line mark on the bag.

Storage and Transport Instructions

Storage time (must not exceed 6 hours) limits, transport (<10 ¡ãC) and storage temperatures (1-4 ¡ãC).

Causes for Rejection

Sample is submitted ¡Ý 10 ¡ãC when submitted and > 2 hours has elapsed since collection, sample submitted frozen, sample with no identification, sample submitted in an unsatisfactory container, insufficient sample volume, and submitted in a leaking container.

Limitations of the Procedure

The detection limit of the test is dependent on the volume of sample analyzed and dilutions selected when calculating and reporting results.

Interfering Substances

Overgrowth of heterotrophs by non-coliform. Heterotrophic bacteria in the sample such overgrowth of heterotrophs could suppress the growth of coliform bacteria and therefore mask their presence in the sample.


1.      Eaton, A. D., L.S. Clesceri and A. E. Greenberg, eds. 1995. Standard Methods for the Examination of Water and Wastewater, 19th ed. American Public Health Association, American Water Works Association, Water Environment Federation. Washington, D.C.

2.      Multiple Tube Fermentation Technique for the Detection and Quantitation of Total and Fecal Coliforms in Non-potable Water. 2006. Louisiana Department of Health and Hospitals, Office of Public Health, Laboratory Services. New Orleans, Louisiana.

3.      U. S. Environmental Protection Agency. The  NELAC web site.