DPD dispenser for chlorine testing

EZ DPD main image
Use in field tests for free or total chlorine in water for 5 mL and 10 mL samples.

  • Dispense reagent with the press of a button.
  • Avoid messy powder handling and leftover foil pouches.
  • Refill dispenser quickly and easily.
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  • Eliminates foil packets.
  • Recessed mouth fits different sized sample vials.
  • Works with wide range of colour cubes, colour wheels, and colorimeters.
  • Colour coding distinguishes free and total chlorine tests.
  • Dispenses reagent in one quick step.
  • Reduces hands-on time.
  • Refill vials screw on quickly and easily.
  • Eliminates risk of powder trapped in corners of foil pouches.


How EZ DPD works

EZ DPD dispenses a premeasured dose of N, N-Diethyl-p-phenylenediamine (DPD) into a 5 mL or 10 mL sample. The DPD reacts with chlorine in the sample to produce a pink colour change. The intensity of the colour is proportional to the amount of chlorine in the sample.

Colorimetric test kits (not currently sold by IDEXX) allow the sampler to interpret the intensity of the colour change, providing a quantitative measure of the amount of chlorine in the sample. EZ DPD detects chlorine between 0.1–3.5 parts per million (ppm).

How to Use


A guide to using EZ DPD



  • Fill sample vial (not from IDEXX) with water you wish to test.
  • Place EZ DPD over sample vial and press button once.
  • Read results according to procedure explained in your test kit.


  • To refill, unscrew empty reagent vial.
  • Uncap refill vial and screw into dispenser top.


  • EZ DPD works with a wide range of chlorine test kits.

Q & A

Frequently asked questions and answers

What is free chlorine?
Chlorine present as Cl2, HOCl, and OCl— is free available chlorine. The active chlorine in the water for disinfection is also called free chlorine residual.

What is combined chlorine?
Combined chlorine is that which is bound to other elements or organic compounds but is still an effective disinfectant. Combined chlorine has been found to be more effective than free chlorine in controlling postdisinfection bacterial growth. Chloramines are an example of combined chlorine.

What are chloramines?
Chloramines are compounds formed by the reaction of chlorine and ammonia nitrogen in water.

What is total chlorine?
Total chlorine is the combination of free chlorine and combined chlorine.

What is residual chlorine?
Residual chlorine is the chlorine that has not combined with organic matter.

What is the amount of DPD powder delivered by the EZ DPD dispenser?
The EZ DPD Test dispenser will deliver 0.04–0.09 grams of DPD powder each time the button is pressed.

What is the chlorine ppm detection range of the EZ DPD test?
The EZ DPD Test detection range is from 0.1–3.5 ppm.

Can I use EZ DPD for testing 25 mL samples?
Yes. Press the button 3 times for each 25 mL sample.

What should be done if the EZ DPD dispenser is plugged?
Remove the dispenser from the vial and clean it to dislodge any plugs. This can be done with a swab or other small device. The dispenser can also be cleaned with water. If you clean the dispenser with water, make sure it is dry before putting it back on a vial of reagent.

What should be done if the EZ DPD powder has clumped?
If the powder clumps, shake the vial to ensure free-flowing powder before dispensing.

What chlorine testing products will the EZ DPD Test work with?
EZ DPD is capable of working with many products on the market, including: Hach Pocket Colorimeter, Hach color wheel, Hach color cube, and LaMotte colorimeter.

Hach and Pocket Colorimeter are trademarks of the Hach Company. LaMotte is a trademark of LaMotte Chemical Products Company.

Tests & Accessories

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>>  Search the Water Tests and Accessories tool

Resources & Product Information


IDEXX Water has reference materials and approval documents to support the many products in our water portfolio.

IDEXX Water Customer Support

UK Headquarters

IDEXX Technologies Ltd Units 1B & 1C, Newmarket Business Park, Studlands Park Avenue, Newmarket, Suffolk, CB87ER

Tel: 01638 676800


ISO Certifications

File Icon  ISO 9001:2008

File Icon  ISO 17025:2005

File Icon  ISO 14001:2004