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Ozone Test Kits

A Banner Image Showing an Ozone CHEMets Test Kit and an Ozone Single Analyte Meter

What is ozone?

Ozone (O3), a gas composed of three oxygen atoms, is very reactive. This reactivity makes it a strong oxidizing agent. It is often used as a disinfectant in a wide range of processes like viral, bacterial and parasitic disinfection. O3 can be used in water to remove taste, odor and color-affecting compounds. Ozone is also used to oxidize inorganic impurities such as iron, manganese and sulfides and has been shown to improve coagulation processes. Drinking water facilities often use ozone as an alternative to chlorine for drinking water disinfection. Ozone has increased in popularity as a water treatment method as regulatory limits for allowable concentrations of disinfection byproducts (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs), have become more challenging for municipalities to meet. Ozone can reduce DBP’s in two ways:

  1. When used as either a pre-oxidant or as the primary disinfectant, it can significantly lower the amount of chlorine required as a secondary disinfectant in the distribution system.
  2. When ozone is used in conjunction with biologically active filters, it can significantly reduce the amount of organic material available to be chlorinated which helps to limit DBP formation.

Water bottling facilities use ozone as the last disinfection step just prior to bottling. They must ensure a low level of ozone residual is maintained to meet regulatory limits. Ozone is also used in aquaculture (nitrite oxidation), pools and spas, groundwater remediation, winery and brewery sanitation (barrel/tank cleaning), electronics (surface cleaning), cooling water towers, laundry, and general industrial wastewater treatment.

Why test for ozone?

If it is being used as a disinfectant, O3 water testing is critical to ensure that the concentration is high enough to remove harmful agents. Excess disinfectant is costly and, when used for drinking water disinfection, can itself affect odor and taste. Frequent testing of the concentration of dissolved ozone in water keeps systems running at peak efficiency.

About our ozone test kits

Two ozone test methods are available that offer different measurement ranges:

  • The DPD method develops a pink color in the presence of ozone.
  • The indigo trisulfonate method uses a blue dye which fades in the presence of ozone. The indigo method is specifically called out in the US National Primary Drinking Water regulation so it is the method of choice for many water bottling operations.

CHEMetrics visual ozone test kits feature CHEMets® self-filling ampoules that contain pre-measured reagent for a single test. Simply snap the ampoule directly in a sample to draw in the correct volume of sample and then compare to the supplied color standards to find the concentration.

CHEMetrics also offers instrumental ozone test kits featuring Vacu-vials® ampoule technology. Vacu-vials ampoules feature a 13mm diameter and utilize the same self-filling technology as CHEMets ampoules. The Vacu-vials that utilize the DPD chemistry are compatible with most photometers or spectrophotometers.

Unlike other ozone test kits, CHEMetrics indigo trisulfonate test kit features a self-zeroing chemistry that eliminates the need to generate an initial indigo trisulfonate absorbance ampoule each time a test is run. Only one ampoule is needed for each O3 water test! These Vacu-vials tests require the use of Single Analyte Meter.

Click on a catalog number below for more information or to purchase a test kit.

Visual Kits

Range MDL Method Kit Catalog No. Refill Catalog No.
0-0.60 & 0.6-3.0 ppm 0.025 ppm DPD K-7404 R-7404

Instrumental Kits

Range Method Kit Catalog No.
0-0.75 ppm Indigo K-7433
0-0.75 ppm Indigo I-2022
0-5.00 ppm DPD K-7423
0-5.00 ppm DPD I-2019


The DPD Method

References: USEPA Methods for Chemical Analysis of Water and Wastes, Method 330.5 (1983). APHA Standard Methods, 23rd ed., Method 4500-Cl G- 2000.

Potassium iodide is added to the sample before analysis. Ozone reacts with the iodide to liberate iodine. The iodine reacts with DPD (N, N-diethyl-p-phenylenediamine) to form a pink color. Results are expressed as ppm (mg/L) O3.

For information regarding ozone analysis in the presence of chlorine using the DPD chemistry, see the Technical Bulletin under the Technical Information tab on the individual product pages.


The Indigo Method

References: Bader H. and J. Hoigné, “Determination of Ozone in Water by the Indigo Method,” Water Research Vol. 15, pp. 449-456, 1981. APHA Standard Methods, 23rd ed., Method 4500-03 B-1997.

With the indigo method, indigo trisulfonate dye immediately reacts with dissolved ozone in water. The color of the blue dye decreases in intensity in proportion to the amount of ozone present in the sample. The test reagent is formulated with malonic acid to prevent interference from up to at least 10 ppm chlorine. Results are expressed as ppm (mg/L) O3.The CHEMetrics Indigo Ozone Vacu-vials® Kit employs an innovative “self-zeroing” feature to eliminate the need to generate a reagent blank. Each Vacu-vials® ampoule is measured before and after being snapped in sample. The change in color intensity, measured in absorbance, between reagent in the unsnapped and snapped ampoule is used to determine the ozone concentration of the sample.