Existing medium height RC frame structures with masonry infill panels can be made earthquake safe by limiting the story drift to 0.2% and thereby ensuring compressive strut action of masonry panels in load resisting mechanism. The tuned sloshing water damper (TSWD) is an effective system for reducing displacement response of structures. The TSWD based systems are sensitive to characteristics of host structures and excitations imposed. The single frequency TSWD systems can be optimally designed and executed for targeted response control of accurately assessed structures against well-defined excitations. The multiple frequency TSWD is a robust system for response control of approximately assessed structures against dynamic excitations. A simulated shake table experimental study has been conducted on a reduced scale model of an existing structure. A retrofitting regime for 25% displacement response reduction of the existing structure has been proposed with multiple frequency TSWD system mounted on its roof. The reduced response shall limit the story drift and ensure the compressive strut action of masonry panels.