• USA Home
  • 37194 - Water hardness (total) test sticks Aquadur®, 3-21°d

37194 Sigma-Aldrich

Water hardness (total) test sticks Aquadur®, 3-21°d

Graduation: 3 − 4 − 7 − 14 − 21 °d



General description

The hardness of water is expressed in mmol/l or in the older common unit degrees of hardness, whereby it is important to differentiate between German, English and French interpretation:

in Germany: 1 °d = 10 mg/l CaO = 17.8 mg/l CaCO3
in Great Britain: 1 °e = 14.3 mg/l CaCO3
in France 1 °f = 10 mg/l CaCO3

Conversion factors: 1 °d = 1.25 °e = 1.78 °f = 0.178 mmol/l
In the USA, the water hardness is simply expressed in terms of mg/l CaCO3. Apart from the above values, water is often simply classified as "soft water", or "hard water" etc. The following values generally apply to these terms:

below 90 mg/l CaCO3 - very soft water
90 − 180 mg/l CaCO3 - soft water
180 - 270 mg/l CaCO3 - medium hard water
270 - 450 mg/l CaCO3 - hard water
above 450 mg/l CaCO3 - very hard water

The hardness of water is often of importance where no laboratory facilities for the analytical determination exist. In these cases Aquadur® provides a quick method for an indicative reading. Its sensitivity is adequate for textile establishments of moderate size, in dyeing, laundries, small water works, boiler rooms as well as in pisciculture, aquaria and also for household use.


test sticks, package with 100 pieces

Legal Information

Aquadur is a registered trademark of Macherey-Nagel GmbH & Co., KG

Price and Availability

Safety & Documentation

Safety Information

Safety Information for this product is unavailable at this time.


Certificate of Analysis

Protocols & Articles
Related Products

Technical Service:

Our team of scientists has experience in all areas of research including Life Science, Material Science, Chemical Synthesis, Chromatography, Analytical and many others.

Bulk Ordering & Pricing:

Need larger quantities for your development, manufacturing or research applications?