Brief Description

Primary drinking water test that simultaneously detects total coliform and E. coli bacteria using defined enzyme substrate technology.

Laboratory Unit

Environmental Bacteriology


Standard Method 9223B Enzyme Substrate, using Idexx Colilert 24-hour Presence/Absence or Colilert 18-Hour Presence/Absence formats. The Idexx QuantiTray format for quantitative results is available upon special request.

Specimen Collection

Click here for sampling instructions. Minimum volume 100 ml.


Ship to MSPHL immediately. Must be received in lab within 30 hours (public water) or 48 hours (private wells) 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)

Potable water from public water supply or private well. Public supply source water samples (surface water and ground water sources).

Test Request Form(s)

Public water samples must be submitted by an official of the public supply following a DNR approved sampling plan. Use the Public Water Sample Form LAB 10B.

The general public may submit private well samples. Test results are considered "Unofficial" and are for informational purposes only. Use the Unofficial Private Water Sample Form LAB 10C.

Private well samples to be used for "Official" purposes, including real estate transactions and health related inspections, must be submitted by an official of the state or local health agency, or a state licensed sample collector/well inspector. Use the Official Private Water Sample Form LAB 10G.

Possible Results

Total Coliform and E. coli "Present" or "Absent".

Reference Range

Total Coliform and E. coli "Absent"

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
Presence of disinfectant
Unapproved container

Interfering Substances

Humic material with innate yellow color

Result Reported

Results are reported to DNR (public water samples) or to the submitter (private water samples) within 24-30 hours of sample receipt in lab (next day).


Private well samples are charged a $10 handling fee. Invoice will be sent with sample results. There is no charge for public water samples submitted by public supplies for their monthly EPA/DNR Safe Drinking Water Act compliance testing.

CPT Codes




Additional Information