Brief Description

Recreational/Environmental water test that enumerates E. coli bacteria using defined enzyme substrate technology.

Laboratory Unit

Environmental Bacteriology


Standard Method 9223B Enzyme Substrate Most Probable Number (MPN), using Idexx Colilert 24-hour QuantiTray format.

Specimen Collection

Click here for sampling instructions. Use sample information form. Minimum volume 100 ml.


Sterile, disposable 120 ml plastic bottle containing sodium thiosulfate. Must use sample kit provided by MSPHL.

Ship to MSPHL immediately. Must be received in lab within 48 hours of sampling. May be stored in refrigerator conditions temporarily prior to shipping. Use of a cooler and ice packs in the field is recommended.

Acceptable Specimen Type(s)

Recreational waters from public pools, hotel pools and spas, and swim beaches. Environmental samples include non-recreational surface waters submitted by a state or local health agency for investigation.
St. Louis Zoo animal tanks and pools are also tested.

Test Request Form(s)

Use the Recreational/Environmental Water Sample Form.

Possible Results

E. coli MPN/100 ml. (Method can also give a Total Coliform MPN/100 ml if appropriate).

Unacceptable Conditions

Transit time exceeded
No date/time collected
No sample identification
Sample form incomplete
Quantity not sufficient (100 ml)
Sample leaked in transit
Sample frozen
P resence of disinfectant
Unapproved container

Interfering Substances

Humic material with innate yellow color

Result Reported

Results are reported to the submitter within 24-30 hours of sample receipt in lab (next day).


Samples are charged a $20 fee. Invoice will be sent with sample results. Testing is performed on a contractual basis with a federal or state agency, or with privately owned entities (homeowners' associations). Contracts cannot be formed with individuals to test privately owned pools or beaches.

CPT Codes




Additional Information

Recreational/environmental water samples must be submitted by an official of the state or local health agency, or a representative of the contractee.  Use the Recreational/Environmental Water
Sample Form.