Seeking Sustainability ch. This is somewhat misleading, however, as not all the salts found in the water are table salts. The TDS measurement includes common elements such as sodium, calcium, magnesium, chloride, sulfate, and bicarbonate that are combined with forms of sulfur and carbon with oxygen.
Water hardness is linked to scale formation and the reduced cleaning efficiency of soaps.
Alkalinity helps control the pH of water. These naturally occurring chemicals help control the pH of water between 7.5 and 8.5. In natural waters moderate alkalinity is beneficial, since it is composed of carbonates that can combine with calcium. CAP water has about 2.5 times the hardness of Tucson groundwater, but CAP alkalinity is about 10 to 20 percent lower. Therefore, the ability of CAP water to form scale may be slightly lower than that of Tucson's groundwater.