HPC for Quanti-Tray®

Heterotrophic plate count made easy for bottling and manufacturing plants

Bottled Water Recreational Water

Simpler detection and quantification of heterotrophic organisms

  • No autoclaving, filtering or agar
  • No colony counting or interpretation
HPC for Quanti-Tray


Call 1300 4 IDEXX or email water@idexx.com.

HPC for Quanti-Tray: Confidence in quantification


  • Convenient 100-ml sample size - test source water, transport vehicle water, manufacturing line water and finished products.
  • Simple procedure needs no special training.
  • Shares the same Quanti-Tray® system as Colilert®, Enterolert® and Pseudalert® tests for maximum efficiency.
  • Results valid at 44–72 hours.
Product Information

Sample size: 100 ml

Time to results: 44–72 hours

Shelf life: Up to 12 months at 2–25°C; store away from direct light

Read: Sample fluoresces to indicate the presence of heterotrophs

Uses: Quantification testing using IDEXX Quanti-Tray®, Quanti-Tray®/2000


Snap packs with Quanti-Tray for 100-ml water samples:

  • 20 test pack No.WHQT-20
  • 200 test pack No.WHQT-200

Snap packs with Quanti-Tray/2000 for 100-ml water samples:

  • 20 test pack No.WHQT2K-20
  • 200 test pack No.WHQT2K-200

How HPC for Quanti-Tray® works

The HPC for Quanti-Tray® Test is used for the quantification of heterotrophic organisms in 100 ml of water.


The test is based on IDEXX-patented Multiple Enzyme Technology™, which detects viable heterotrophic organisms by testing for the presence of key enzymes known to be present in these organisms. The test uses multiple enzyme substrates that produce blue fluorescence when metabolised by water-borne bacteria.


The sample/reagent mixture is added to a Quanti-Tray®, incubated and then examined for fluorescing wells. The number of fluorescing wells corresponds to a most probable number (MPN) of total heterotrophic organisms in the original sample.


The HPC for Quanti-Tray Test detects organisms at 1 cfu/100 ml after 44–72 hours of incubation.



View/Print HPC for Quanti-Tray Procedure 


A step-by-step guide to using HPC for Quanti-Tray


Step 1

Add reagent to sample (sample will turn pink).


Step 2

Pour into Quanti-Tray® or Quanti-Tray®/2000.


Step 3

Seal using a Quanti-Tray® Sealer; incubate for 44 hours.


Step 4

Read under ultraviolet light; count blue fluorescent wells and refer to MPN table.


Frequently asked questions and answers


Which water types can be tested?

The HPC for Quanti-Tray® Test is designed specifically for bottled-water samples. Bottled-water samples are defined as samples taken from any point in the bottled-water manufacturing process (from the original water source, to transportation vehicles, to the manufacturing line, to the finished product).


What is the sample incubation time and temperature?

Water samples are incubated at 36ºC (±2ºC) for 44 hours, and results are valid up to 72 hours.


What is the detection limit?

The HPC for Quanti-Tray Test detects heterotrophic organisms at 1 cfu/100 mL.


Does the test include a comparator?

There is no comparator for the HPC for Quanti-Tray Test. Use a negative control for comparison when you interpret results.


Are results valid prior to 44 hours?

Yes, if the results are positive. An inoculated HPC for Quanti-Tray Test sample that is positive before 44 hours is a confirmed positive test. However, for an accurate quantitative determination of heterotrophic count in a sample, the results should be read between 44 and 72 hours of incubation.


Are results valid after 72 hours?

Yes, if the results are negative. If an inoculated HPC for Quanti-Tray Test sample is inadvertently incubated over 72 hours, lack of fluorescence is a valid negative test. However, a fluorescent read after the 72 hours is not valid and should be repeated or verified.


Can either a 51-well or a 97-well Quanti-Tray® be used?

Yes, both the Quanti-Tray® and Quanti-Tray®/2000 can be used with the HPC for Quanti-Tray Test in the 100-mL format.


What should be the color and consistency of the test powder?

The HPC for Quanti-Tray Test reagent powder should be pink in color and of a free-flowing, granular consistency. Direct any concerns about the color or integrity of the powder to IDEXX Technical Service.


How should customers dispose of a positive HPC sample?

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


Can HPC for Quanti-Tray be used with carbonated water samples?

HPC for Quanti-Tray should not be used with carbonated water samples.


HPC for Quanti-Tray: Everything you need for confident outcomes


Note: Availability varies by country.


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