The water hardness indicates how many alkaline earth metals (especially calcium and magnesium) are present in the water. The higher the hardness of the water, the more of this hardness is in the water. The detergent law regulates the division of the hardness ranges. There are three different hardness ranges:
Water hardness range soft: water hardness less than 8.4 ° dH
Water hardness range medium: water hardness between 8.5 ° dH and 14.6 ° dH
Hard water hardness range: water hardness higher than 14.6 ° dH
A high water hardness is a problem especially in the household. It comes to limescale and higher detergent consumption. In addition, the coffee taste changes with a high water hardness, since the coffee aromas can not develop. In areas with high water hardness, the use of a central water softener in the house is recommended to avoid the problems with hard water.