Abstract: The present invention relates to the process of re-mineralizing treated potable water that has had hardness components removed by dissolving a magnesium compound in the treated water. The resulting concentration of magnesium, pH level and alkalinity level are controlled by the inclusion of a calcium compound such as calcium carbonate and a bypass orifice. The bypass orifice allows a portion of pretreated wafer to bypass a filter that contains the magnesium compound. The process is particularly useful as an in-line process for continuous or semi-continuous treatment of water. The preferred magnesium and calcium compounds include magnesium phosphate dibasic trihydrate and calcium carbonate, respectively.