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Hardness Test Kits

Titrimetric Kits

Range MDL Method Type Kit Cat. No. Refill
50 - 500 ppm as CaCO3 50 ppm EGTA (Calcium) Titrets K-1705
2 - 20 ppm as CaCO3 2.0 ppm EDTA (Total) Titrets K-4502
20 - 200 ppm as CaCO3 20 ppm EDTA (Total) Titrets K-4520
100 - 1,000 ppm as CaCO3 100 ppm EDTA (Total) Titrets K-4585

CHEMetrics offers test kits employing the well-known EGTA and EDTA reagents to deliver sensitivity and accuracy within two minutes or less. Based on CHEMetrics patented Self-Filling Reagent Ampoule technology. Premixed. Premeasured. Precise.

The EGTA Method (Calcium)

The EGTA method is specific for calcium hardness. The EGTA titrant in alkaline solution is employed with a zincon indicator. Results are expressed as ppm (mg/l) CaCO3.

Shelf-life: eight months. Although the reagent itself is stable, the end point indicator has a limited shelf-life. We recommend stocking quantities that will be used within seven months.

West, T. S., DSC, Ph.D., Complexometry with EDTA and Related Reagents, 3rd ed., pp. 46, 164 (1969).

The EDTA Method (Total)

The EDTA titrant is employed in alkaline solution with a calmagite indicator. This method determines the combined calcium and magnesium concentration of a sample. If no magnesium is present, the end point of the titration normally appears sluggish. Results are expressed as ppm (mg/l) CaCO3.

APHA Standard Methods, 22nd ed., Method 2340 C- 1997.
USEPA Methods for Chemical Analysis of Water and Wastes, Method 130.2 (1983).

Titrets Technology

CHEMetrics Titrets employ reverse titration technology, meaning that the premixed and premeasured alkaline titrant is in the ampoule, and the sample and indicator is drawn in a little at a time from the sample cup. The amount of sample required to neutralise the acid titrant is proportional to the hardness of the sample, which is shown on the scale on the side of the ampoule.


Hardness is a measure of the mineral content of water and is dependent on the local geology. Calcium and magnesium are the most common minerals that contribute to hardness. Hard water causes scaling in boilers and other industrial equipment, and diminishes the effectiveness of soaps and detergents. Harder water requires more soap to produce a lather. The total hardness method is applicable to drinking, surface, boiler, and brine waters.

Hardness is related to alkalinity as both measure CaCO3 content. However, hardness is also a measurement of other dissolved metals that do not necessarily neutralise acidity.