H2O News

10 years of Colilert®-18, with expanding approvals and applications

This year marks the tenth anniversary of the IDEXX Colilert®-18 test as a United States (U.S.) EPA-approved method for drinking-water analysis under The Total Coliform Rule. Since that time, Colilert-18 remains the fastest U.S. EPA-approved test for total coliform and E. coli analysis, providing completed test results in only 18 hours. In addition to the U.S., water laboratories in over a dozen countries now rely on Colilert-18 for their drinking-water test results.

An 18-hour time to result means that samples run in the afternoon can be read first thing the following morning. This improves the laboratory workflow because the recording of results, resampling and paperwork are completed before the next round of afternoon samples arrives. This eliminates the afternoon “gridlock” that occurs at many water laboratories. Colilert-18 makes a variety of testing applications easier when time-to-result is important:
  • Emergency resampling and testing
  • New water main installation
  • New home construction
  • Friday samples (results can be read early Saturday, freeing up the weekend)

Recent regulatory changes have spurred an increase in quantitative water testing.

Colilert-18 is now increasingly used in water-testing applications other than drinking water. In 2003, Colilert-18 was approved by the U.S. EPA for ambient water testing in the Ambient Water Rule.¹ This approval includes Colilert-18 and Quanti-Tray® for the testing of E. coli in recreational or swimming waters. More recently, Colilert-18 and Quanti-Tray were proposed for approval by the U.S. EPA for E. coli testing in wastewater in the Proposed Wastewater Rule.2 Additionally, in 2006, Colilert-18, Colilert® and Quanti-Tray were approved by the U.S. EPA for source-water testing under the LT2 Rule.3 In the United Kingdom, Colilert-18, in combination with Quanti-Tray, has been accepted for testing waste sludge generated from the wastewater treatment process. For an overview of Colilert-18 and IDEXX’s other test reagents, see the chart below. Learn more about Colilert-18.

H2O Fact

In the recently promulgated U.S. EPA LT2 Rule, Colilert and Colilert-18 are the only two E. coli methods that allow for a 48-hour sample-holding time, as compared to 30 hours with other methods. For more information on the LT2 Rule, visit www.epa.gov/lt2.
1
U.S. Federal Register – 40 CFR Part 136 Vol. 68, No 139, July 21, 2003
2
U.S. Federal Register – 40 CFR Part 136 Vol. 70, No 157, August 16, 2005
3
U.S. Federal Register – 40 CFR Parts 9, 141 and 142, January 5, 2006


TECH TIP

Certificates of quality for IDEXX products can now be downloaded directly from our Web site. Download certificates now.
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