Abstract: A mixer tap unit has a body connected to a nozzle having two separate water passages extending the length of the nozzle. A hot water connection, a cold water connection and a filtered water connection are provided for the body. In use, the hot and cold water can mix in a mixing chamber in the tap body and flow along the passage. Filtered water flows separately along the passage. Valves are provided to respectively control the flow of the hot, cold and filtered water. In a preferred form, a chamber allows carbonization of the filtered water prior to delivery to the tap body and the supply of CO.sub.2 gas to the chamber is controllable by a valve. The valve is operated in a first direction to inject CO.sub.2 gas into water in the chamber, and in a second direction to allow the carbonated water to flow to the nozzle.