A dual-purpose household water purifier includes a main unit and an expansion unit which can be detachably connected. When the main unit is connected with the expansion unit, a booster pump can pressurize tap water entering a filter assembly. In the dual-purpose household water purifier, the main unit can be used as a non-electric drive water purifier. After the tap water enters the filter assembly and is filtered. The purified water flows into the purified water chamber of the pressure bucket, and the user takes the purified water. It is further provided an expansion unit. When the main unit is connected to the expansion unit, the booster pump can pressurize the pipeline, reducing application environmental restrictions on the water purifier. Through arrangement of the expansion unit, the water purifier can be operated in two operation modes of non-electric drive mode and electric drive mode.