Louisiana Department of Health & Hospitals | Kathy Kliebert, Secretary

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Fecal Coliform Enumeration Test in Water

E. coli Enumeration Test of Source Water Samples

PHL Location

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

CPT Code



LT2 ONPG-MUG, 97-Well Analytical Test Method; LT2 Test

Brief Description of Test

The enumeration of E. coli in source water using SM9223 (Colilert Quanti-tray 2000).

Possible Results

E. coli Most Probable Number (MPN)/ 100 ml

Reference Range

A mean of 50 E. coli for flowing stream and a mean of 10 E. coli for reservoir/lakes.

Specimen Type

Source Water

Specimen Container(s):

Sterile, disposable 7oz. Nasco Whirl-Pak bag.

Minimum volume accepted:

120 ml

Collection Instructions

Collect representative sample according to established protocols.  Use a Whirl-Pak bag and fill leaving at least 1 inch of air space at top of container.  Whirl bag to close.  Do not twist tabs together.

Storage and Transport Instructions

Store & transport sample(s) in clean iced cooler(s).  Samples must be at <10¨¬C when received. Maximum holding time is 30 hours.

Causes for Rejection

Sample > 30 hours old; Frozen water sample; No sample ID; Unsatisfactory collection container; insufficient amount of sample; sample container leaking;  sample information form not complete. Sample temperature >10¢ªC upon receipt.                             

Limitations of the Procedure: Not suitable for marine water or any sample altered by any pre-enrichment or concentration.

Limitations of the Procedure

Not suitable for marine water or any sample altered by any pre-enrichment or concentration.

Interfering Substances

Samples containing humic material with innate color.


Idexx Laboratories Colilert, Colilert 18 package inserts; LA DHH-OPH Laboratory Services SOP DOLSOPDWM-01 Chromogenic Fluorogenic Substrate Method.

Additional Information

Complete a Lab 8 Laboratory Request and Report Form. The following is required Lab 8 information:  Sample sequence #¡¯s and Project Code, Name of Supply, Collected by (name or initials), PWS ID, Date/Time Collected. Type of source water, turbidity.