A modular printhead assembly includes an elongate substrate member that defines a plurality of holes. An ink conduit is mounted longitudinally on one side of the substrate member and defines a plurality of ink holes to be in fluid communication with the ink holes defined by the elongate substrate member. A plurality of printhead module assemblies is mounted along an opposite side of the substrate member. Each module assembly includes an ink feed structure in fluid communication with the ink holes defined by the elongate substrate member and a printhead integrated circuit in fluid communication with the ink feed structure. A bus bar assembly is arranged on the substrate member for providing the printhead integrated circuits with power.