Abstract: The invention relates to RO water purifier (100) with provision for dispensing hot or cold water. The device has a user-interface through which a user can choose how hot the purified water should be. The RO water purifier (100) comprises a compartment (9) for storage of pre-heated or pre-cooled purified water. The compartment comprises an inlet for return of any undispensed purified hot, cold, or ambient water to flow back from the user-interface. The compartment has an outlet for pre-heated or pre-cooled purified water to flow out into a device (8) for heating or cooling it further as desired by the user. The device for heating or cooling the purified ambient water is configured to heat the water to 80 to 95° C. or alternatively, is configured to cool it to 15 to 5° C., and wherein in said e compartment said pre-heated water is stored at 40 to 75° C. and when it is pre, cooled it is stored at 10 to 20° C., and wherein temperature of said purified ambient water is 25 to 40° C.