A water treatment apparatus includes a water receiver configured to receive an input of water; and an installation mechanism configured to include one or more slots in which a module for water treatment is installable. Among a plurality of types of modules available to be selected in accordance with a use of water treatment, at least one module includes a filter as a component, and the water treatment apparatus is configured to provide a water treatment function corresponding to the module to the water received at the water receiver by installing the module in one of the one or more slots.