However, calcium ions are a major contributor to water hardness. Hard water has a noticeable taste, produces precipitates with soaps which inhibits lathering and forms precipitates in boils, hot water systems and kettles. Temporary hardness is due to Ca(HCO3)2 when deposits CaCO3(s) as scale on boiling the water. Ca2+ and Mg2+ can combine with Cl- and/or SO42- causing permanent hardness, which cannot be removed by boiling. Calcium ion can be determined by atomic absorption spectroscopy (AAS)