You may have heard the terms soft water and hard water.
These are determined by the amount of minerals contained in the water.
Calcium content x 2.5 + magnesium content x 4 = hardness
and generally,
Soft water less than 100 hardness
Medium hard water with a hardness of 100 to 300
Hard water with a hardness of 300 or more
classified as
The lower the hardness, the lighter and mellower the water, making it easier to drink.
Japanese mineral water is mostly soft water. Japan is a volcanic country, with a large proportion of pumice-like igneous rocks in the stratum, and a steep slope from the mountains to the coast. In other words, even if it rains a lot, groundwater infiltrates and flows out quickly, so it is difficult for minerals to dissolve in the soil. Therefore, the mineral water, which is obtained by sterilizing the groundwater pumped from the water source, naturally has a low mineral content.