Drinking water testingTotal Coliforms and E. coli Presence-Absence Test (Order code: 8040)MethodEnzyme substrate—Chromogenic Standard Methods 9223 B Colilert DescriptionThis test employs the IDEXX, Inc Colilert ™ system, allowing the detection of total coliforms at one colony-forming unit (1 CFU equivalent) by hydrolysis of ortho-nitrophenyl-ß-D-galactoside and Escherichia coli by hydrolysis of 4-methyl-umbelliferyl-ß-D-glucuronide. This is the most common test for determination of the potability of drinking water, whether collected from a water system or a well. Reference rangeTotal coliforms and E. coli tests should be negative for a water sample to be considered a safe drinking water source. Turnaround time1 day
Total Coliforms and E. coli MPN, undiluted (Order code: 8350)MethodEnzyme substrate—Chromogenic Standard Methods 9223 B Colilert DescriptionThis test employs the IDEXX, Inc Colilert™ Quantitray system, allowing the detection and enumeration of total coliforms by hydrolysis of ortho-nitrophenyl-ß-D-galactoside and Escherichia coli by hydrolysis of 4-methyl-umbelliferyl-ß-D-glucuronide. Enumeration results in the reporting of a Most Probable Number (MPN) and is commonly used to determine the microbial load of both the total coliforms and E. coli. Reference rangeTotal coliforms and E. coli should be less than 1 MPN per 100 mL for a single sample. Turnaround time1 day
Heterotrophic Plate Count (Order code: 8045)MethodColony count by pour plate Standard Methods 9215 B DescriptionThe heterotrophic plate count (HPC) procedure estimates the number of live heterotrophic bacteria in a water sample. The number of colony-forming units (CFUs) is the final colony count that may arise from pairs, chains, clusters, or single bacteria as well as interaction among developing colonies. The test does not differentiate between type of bacteria. Reference rangeThere are no defined limits for this test. Turnaround time2 days |
County of San Luis Obispo
Public Health Laboratory
Drinking water testing