硬水是含钙盐与镁盐较多,硬度大的水质,也就是水中含有钙与镁的碳酸盐、酸式碳酸盐、硫酸盐、氯化物以及硝酸盐所形成的。如果水质含有铁盐或其他矿物质时,也可形成硬度,但因含量极少,一般以钙与镁含量的总和为水的硬度。硬度单位通常用的有两种:一种是用:毫克当量/升表示;另一 Hard water is calcium and magnesium salt more hardness of water quality, that is, water contains calcium and magnesium carbonate, acid carbonate, sulfate, chloride and nitrate formed. If the water contains iron salts or other minerals, but also the formation of hardness, but very little, usually the sum of calcium and magnesium content of water hardness. Hardness units are usually used in two ways: one is used: milliequivalents / liter said; the other