Modified Colitag™ 16-Hour Presence-Absence Test 

Modified Colitag

Hach Modified Colitag™ is the fastest coliform presence-absence test in the market. Test your water at 5:00 pm and have your results by 9:00 am the next day!  The product also provides unparalleled flexibility by offering two testing parameters (16 or 22 hour test) in one product.

The fastest on the market at 16 hours

  • Fastest EPA-approved test for coliforms and E. coli
  • Test as late as 5:00 PM and still have results by 9:00 AM the next day

One product that supports 16- or 22-hour test methods

  • Allows for a "standard" test that requires less setup, or a "rapid" test when necessary
  • One media for both tests reduces complexity in certification and inventory

Results are valid for up to 32 hours

  • Saturday’s tests can be read on Monday – no need to work all weekend
  • Results stay valid for 8 times longer than the competition

Learn More or call 800-227-4224

Hach Modified Colitag Procedure

Snap to Open Hach Modified Colitag

Step 1: Snap to open Hach Modified Colitag Pack

Shake to dissolve media

Step 3: Shake sample, media will not dissolve immediately

Check for yellow color

Step 5: Check for yellow color, indicating coliforms

Add Hach Modified Colitag to water

Step 2: Add Hach Modified Colitag to 100 mL water sample


Step 4: Incubate for 16-22 Hours at 35°C ±0.5°C

Check for e coli

Step 6: Check for fluorescence with UV light, indicating E. Coli