How does the water hardness develop?


COdissolved in rainwater (carbon dioxide and water are carbonic acid) is responsible for rainwater being slightly acidic (pH <7.0).

Air pollutants such as sulfurous acid and nitrous acids may exacerbate the acidity of the water. These weak acids are able to dissolve calcareous rocks. The dissolved magnesium (Mg) and calcium (Ca) compounds form the main components of the water hardness. They are not thermally stable, decompose at temperatures of 60 ° C and higher and precipitate as precipitation (turbidity of the water).

Rock without lime (such as granite) is not soluble in acid rainwater and therefore not more hard-wearing.

The water hardness is a practical term and refers to the water constituents, which lead to unwanted encrustations when heating the water, but also during evaporation.

The total hardness is the sum of calcium and magnesium ions. If one speaks of the hardness of water, then this sum is a measure for it.

The carbonate hardness corresponds to the anions derived from carbonic acid.

The permanent hardness (also called non-carbonate hardness) is the total hardness minus the carbonate hardness, that is, the proportion of the hardness that remains after boiling the water.

  • How does the water hardness develop?