Did you know that the hard water containing calcium bi-carbonate (the kind that leaves a calcium deposit in your tea kettle) is the best for drinking? As annoying as it is to have those deposits, you should cheer when you see them because then you know you are getting some sorely needed minerals. Do not confuse calcium bi-carbonate with calcium carbonate. Calcium carbonate is a white, insoluble solid occurring naturally as chalk, limestone, marble, and calcite, and forming mo