Water softeners have been around for a long time and are still the greatest method for removing lime scale from water. Ion exchange is the method by which water softeners remove lime from water. Ion exchange occurs when hardness ions (lime) in water are replaced by sodium or potassium ions (salt). All of the resin beads are laden with sodium ions, and when water runs over them, the sodium exchanges places with the calcium and magnesium in the water. The calcium and magnesium then adhere to the resin. This is also why the water thereafter has a greater salt level and may taste considerably different than before.