We offer low-level gamma-irradiated Colilert-18 product to improve quality and eliminate possible contamination from coliform bacteria. View FAQs on irradiation.

Colilert-18 detects coliforms and E. coli at 1 organism/100 mL.

Colilert-18 shelf life is up to 15 months from date of manufacture.

The powder should be dry and free flowing. A slight tinge of color may be observed when Colilert-18 is added to the water sample, but this in no way interferes with the "readability" of the test. Any concerns about the color or integrity of the powder should be directed to IDEXX Technical Service.

Yes, presence/absence (P/A) samples need to be prewarmed; however, Quanti-Tray® or Quanti-Tray®/2000 samples do not. For P/A, if the sample is not already at 33–38°C, place the sample in a 35°C waterbath for 20 minutes or a 44.5°C waterbath for 7–10 minutes. This prewarming time is part of (not in addition to) the 18-hour incubation period.

Yes, if an inoculated Colilert-18 sample is inadvertently incubated beyond 18 hours, the result is stable for 4 additional hours (22 hours maximum incubation). Heterotrophic organisms are suppressed during the incubation. After 22 hours, a negative test is valid, but any yellow color greater than or equal to the comparator is not valid and should be repeated or verified.

Yes, Colilert-18 can be run with Quanti-Tray®, Quanti-Tray/2000® or any multiple tube format.

Review the faecal coliform procedure in the Colilert-18 Fecal Coliform Protocol Addendum (PDF).

Check with your local, state and/or federal authorities for proper disposal of bacteriological biohazard materials at your facility.

2–25°C away from light.