A household apparatus for treating water has a water treatment reactor; a dispense water path extending from the water treatment reactor to a dispenser whereby treated water produced in the water treatment reactor exits the apparatus by the dispenser; a filter removably mounted in the dispense water path; and, a sensor, (which may be a timer, a flow rate sensor and/or a back pressure sensor) for monitoring the flow of a treated water through the filter, the apparatus issuing a signal advising a user to change the filter when the time for the treated water to flow through the filter exceeds a predetermined value.