Phobos
Staff Emeritus
Science Advisor
Gold Member
- 1,956
- 7
The "hardness" of water is defined by the amount of "polyvalent cations" present in the water (i.e., the amount of salts like calcium or magnesium carbonate). "Hard" water has more of that stuff dissolved in it and "soft" water has less. There's a limited number of health studies available about drinking hard vs. soft water. (maybe I can discuss a few when I get more time)