Abstract: A filter system for a liquid, which system has a base with an inlet for incoming unfiltered liquid and an outlet for outgoing filtered liquid and a filter subassembly having a filter unit and structure for removably maintaining the filter unit in an operative position on the base. There is a first lead-in port on the base in communication with the base inlet and a first lead-out port on the base in communication with the base outlet. There is a second lead-in port on the filter unit and a second lead-out port on the filter unit. The filter unit further has structure for filtering liquid communicating between the second lead-in port and the second lead-out port.