Standard for hardness test of water quality
The hardness of water indicates the plasma content of calcium, magnesium, iron, aluminum and zinc in water.
Water hardness is the property of water resistance and soap bubbles, and it is an old concept used to describe the content of calcium and magnesium in water.
Hardness has different concepts and definitions in different countries, but all kinds of hardness refer to the content of CaO or CaCO3 in a certain volume of water.