Calcium, dissolved

Overview

Calcium is a cation that is present in nearly all natural waters, although concentrations vary. Calcium is present in nearly all rocks and soils present and is frequently the dominant cation in natural waters. One of the more common sources of calcium in water is from the dissolution of limestone. High calcium concentrations are undesirable because the water would be less useable as a drinking- water source and can cause the formation of lime deposits in pipes. Information of the hardness of water is used by water treatment managers to determine amounts of chemical to add during the treatment process.