Water hardness classification

Frieda S. : With your recommendations for water ionizers you always state the hardness levels in °dH (degree of German water hardness). In the analysis of my water provider these are stated in mmol/l. On mineral water bottles it is written in mg/l. How can you compare these classifications?

  • You can investigate. As a consumer you have the right to information. I really don’t know how this terminology jumble can be useful to consumers. It is like with the international standardisation and makes most uncertain. Maybe the drinking and mineral water industry doesn’t want people to compare straight away. For self help, here an aid:
  • The prior indication that was usual for the contents in mg/l (miligrams per litre), which can still be found on mineral water bottles, differs from the modern description with mmol/l (=milimole per litre). To be able to compare your drinking water with mineral water, you have to multiply the stated value in mmol/l with the below shown molar mass of the corresponding atoms and then you obtain the value in mg/l.
  • Sodium (Na+): 22,99
  • Potassium (K+): 39,1
  • Calcium (Ca2+): 0,08
  • Magnesium (Mg2+): 24,31
  • Iron (Fe-II): 55,85
  • Manganese (Mn2+): 54,94
  • Ammonium (NH4+): 18,039
  • Hydrogen carbonate (HCO3-): 61,017
  • Chloride (Cl-): 35,45
  • Sulphur (SO42-): 96,066
  • Sulphide (S2-): 32,07
  • Nitrate (NO3-): 62,004
  • Nitrite (NO2-): 46,005
  • Phosphate (HPO42-): 95,974
  • Silica (SiO2): 60,088

The conversion of the hardness of water results as follows:


Some water providers limit themselves to not publish a complete analysis. You only receive it when requested.

Swiss water hardness ranges


Many state solely the hardness of the German Washing and Cleansing Agents Act from 2007. Only 3 hardness ranges are in this act.
In Germany you have water hardness over dH 30. In the past, the stronger subdivided upper half above dH 15 was phased. So no one has to still claim that hard water was delivered.

Water hardness chart Germany England France USA


Yet this difference still exists in Switzerland. In Switzerland you differentiate the hardness range according to 6 hardness levels in French degrees, respectively mmol/l as follows:

Hardness range chart Millimol Calcium Carbonate per litre dH


Excerpt from the book “Karl Heinz Asenbaum: Electrically activated water – An invention with extraordinary potential.”
Copyright 2016 

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About Karl Heinz Asenbaum

The Munich-based journalist has been working on the topic of "alkaline activated water" since 2004. For 12 years he worked closely with the alternative physician Dr. Walter Irlacher, with whom he wrote two successful books: "Service Manual for Humans” (Service Handbuch Mensch) (2006) and "Drink Yourself Alkaline” (Trink Dich basisch) (2008,2011). Since 2014 he has been contributing his knowledge and experience to Aquacentrum and giving lectures worldwide. “Electro-activated Water", the world's most comprehensive book on the subject, was published in 2016. View all faqs by Karl Heinz Asenbaum 

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