Potable Water


Potable Water – Total Coliforms/Escherichia coli Detection

Laboratory Fee Schedule

Procedure #:  MZZ0441A

CPT:  N/A

Potable Water – Total Coliforms/Escherichia coli Detection

 Synonym(s):  Total coliform, Drinking Water Test
 Requisition Form G-19
 Test Description Detects the presence of E. coli and total coliform bacteria in potable water
 Pre-Approval Needed N/A
 Supplemental Information Required N/A
 Supplemental Form(s) N/A
 Performed on Specimens from (sources) Food
 Sample/Specimen Type for Testing Water (potable; non-silo dairy) samples
 Minimum Volume/Size Required 105 mL
 Storage/Preservation Prior to Shipping
  • Place sample in water-tight, wide-mouthed container with a capacity of at least 120 mL (4 oz)
  • Sodium thiosulfate (100mg/L) must be added to containers before sterilization (0.1 mL of 10% sodium thiosulfate solution, appropriate tablet, or powder).
  • Potable water samples must be tested within 30 hours of collection.
  • Non-silo dairy water samples must be
    • tested within 6 hours of collection if not refrigerated (temperature control not required); or
    • maintained at 0.0° to 4.5°C and shipment must include temperature control.
 Transport Medium N/A
 Specimen Labeling Sample Identification must match submission form.
 Shipping and Specimen Handling Requirements
  • If shipped, samples must be shipped for overnight delivery.
  • Potable water samples must be tested within 30 hours of collection
  • Non-silo dairy water samples that will not be tested within 6 hours of collection must be maintained between 0.0° to 4.5°C while in transit and include a temperature control. 
 Method Colilert® test 
 Turn-around Time 1 Day
 Interferences/Limitations
  • Can detect E. coli and/or total coliform bacteria at a sensitivity of 1 CFU/100 mL
  • In samples with excessive chlorine, a blue flash may be seen when adding Colilert® or Colilert®-18. If this occurs, sample will be considered invalid and testing will be discontinued.
 Common Causes for Rejection
  • insufficient specimen
  • improperly stored
  • failure to meet shipping guidelines
 Additional Information N/A




Last updated November 18, 2021