Where do you draw the line between hard and soft water?
The answer to the question ‘what exactly is hard water?’ is a matter of mineral concentration, measured in milligrams per liter or grains per gallon.
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Each country may have a different standard for what constitutes hard water, but in the United States, the American National Standards defines soft water as containing less than 17.1 mg/L.
Generally speaking the following levels be used to assess water hardness:
0-60 mg/L: soft
121-180 mg/L: hard
more than 180 mg/L: very hard
The most common dissolved minerals are calcium and magnesium, both alkaline earth metals found in the 2nd group of the periodic table. These elements have a 2+ charge so they lose two electrons to form cations, such as Ca