1 to 100 ppm as in us tap waters or from 100 to 600 as in some mineral waters the invention may supply health promoting drinking water types fortified with magnesium and other elements selected from calcium iron potassium iodine fluorine zinc or anions such as phosphate the water can be packaged in any type of portable means the product being possibly fortified with vitamins the process and the apparatus of the invention comprise dissolving of magnesium oxide in a flow through reactor in a preferred embodiment the reactor comprises a bed of mgo through which a carbonized aqueous stream flows in a preferred embodiment the aqueous stream is pumped and circulated through the bed of mgo in a first flow circuit closed circuit and fresh water is fed to and withdrawn from the stream in a second flow circuit open circuit wherein the flow rate through the first circuit is greater than through the second circuit in one arrangement tested in pilot the ratio of the flow rates was 10 the invention will be further described and illustrated in the following examples deionized water was used tap water was used in some of the demonstrations fused mgo screened on 1 mm sieve was used a pvc column of 10 cm diameter and 150 cm height was equipped with five taps at different heights for allowing evaluation of the influence of the residence time of the liquid in the column the column was filled with 3 5 kg of fused mgo to a height of 32 cm the water was fed through the column at various rates co 2 was fed from a cylinder and the flow was controlled.