Clean Water Changes Everything – and It Starts with Reliable Testing

Relied on by communities around the world to ensure clean, safe drinking water, Colitag™ provides your laboratory with a quality and effective choice to test drinking water for total coliform and E. coli with the industry's fastest results. Colitag is an easy-to-use enzyme-substrate test that can detect as low as 1 CFU of total coliform and E. coli in a 100 mL water sample, ensuring you get reliable results for your water testing.

Industry-leading 16-hours Results

Colitag offers the fastest time to results as the only test with a validated 16-hour read window for total coliform and E. coli determination in drinking water.

16–48 Hour Testing Window

Colitag provides unrivaled flexibility with a 16–48 hour read window that allows technicians the freedom to choose the timing that works best for their schedule in a single product.

A Reliable Choice for Drinking Water Testing

Colitag detects as low as 1 CFU of total coliform and E. coli in a 100 mL water sample and is relied on by communities around the world to ensure safe drinking water.

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How Does Colitag Work?

Colitag detects total coliforms and E. coli by identifying two enzymes, β-galactosidase and β-glucuronidase.

If total coliforms are present, β-galactosidase produced by total coliform bacteria hydrolyzes the chromogenic indicator ortho-nitrophenyl-β-D-galactopyranoside (ONPG), releasing a yellow-colored compound.

If E. coli is present, β-glucuronidase produced by E. coli cells hydrolyzes the fluorogenic indicator 4-methylumbelliferyl-β-D-glucuronide (MUG), releasing a compound that fluoresces when exposed to ultraviolet light. E. coli possesses both enzymes, so if the water sample is positive for E. coli, it will turn yellow color and exhibit fluorescence.

Coliform Detection (ONPG)

E. coli Detection (MUG)


  • EPA approved for determination of total coliforms and E. coli in drinking water at 40 CFR 141.852(a)(5)
  • EPA approved for determining E. coli under the Ground Water Rule
  • FDA approved for dairy source waters
  • FDA inclusion in agricultural water

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Colitag Brochure

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Colitag Sell Sheet

Explore our one page reference sheet to learn more about Colitag.

Colitag Training Video

Watch our training video to learn the presence/absence test method.