The concept of water hardness
China stipulates that the total hardness should not exceed 450mg/L, and the World Health Organization recommends the optimal hardness of drinking water as170 mg/L. The hardness of water refers to the content of salt substances dissolved in water, that is, the content of calcium salt and magnesium salt. The hardness unit is ppm, and 1ppm means that the content of calcium carbonate in water is1mg/L. ..
Water below 142 is called soft water, water above 285ppm is called hard water, and water between142 and 285 is called medium hard water. Rain and snow are soft water, while rivers, rivers and lakes are moderately hard water. Spring water, deep well water and seawater are all hard water.
Hard water usually does not cause direct harm to health, but because it contains more calcium salt, the pot we use to boil water is particularly prone to scaling. The precipitation of scale is mainly carbonate and magnesium salt. If it is partially decomposed into the intestine, it will become a constant element for some people. If it can't be dissolved and decomposed, it will be eliminated with feces and will not have a special impact on the body.