The system comprises a valve unit connected to a filtering unit for the selective delivery of cold, hot and mixed sanitary water, respectively either refrigerated or boiling purified water with optional carbonation. The valve unit comprises a base body for housing a first mixer tap, of the cartridge type, which is connected to a first delivery duct of the sanitary water, as well as a second control tap for the purified water, connected to a second delivery duct internal to the previous one. The outlet or each outlet of the purified water of the filtering unit is connected to an inlet of the second control tap, whereas the inlet of the cold water of the filtering unit is directly connected to the inlet of the cold water of the first mixer tap, by means of a branched channel that is provided inside the base body of the valve unit.