The invention concerns a household appliance (1, 100), the household appliance comprising: a washing chamber (20) for washing of items to be cleaned; a water system configured to feed water to and from the washing chamber (20) for cleaning and/or rinsing of the items therein; wherein the water system comprises a UV-treatment chamber (9, 19, 50, 70) for disinfection and/or sterilization of water to be fed to the washing chamber (20) during operation of the household appliance (1, 100), wherein the UV-treatment chamber (9, 19, 50, 70) is provided with at least a first UV-light source (10, 55a, 75a) arranged to direct UV-light towards water present in the UV-treatment chamber (9, 19, 50, 70) The UV-treatment chamber (9, 19, 50, 70) is further provided with at least a first UV-light reflector (56d, 76c). The invention also concerns a method for operating a household appliance (1, 100).