Maintaining printhead using maintenance station with backflush

A capping unit, a waste liquid tank, a valve, and a cleaning liquid tank are provided for maintaining a printhead. The capping unit includes a drain. The waste liquid tank receives a waste liquid from the capping unit. The valve is in fluid communication with the capping unit through a first fluid passage connected to the drain. The valve is also in fluid communication with the waste liquid tank through a second fluid passage. The valve includes a first state that permits the waste liquid to flow from the capping unit through the valve to the waste liquid tank. The valve includes a second state that prevents the waste liquid from flowing from the capping unit through the valve to the waste liquid tank. The cleaning liquid tank is in fluid communication with the valve through a third fluid passage. The cleaning liquid tank is configured to provide a cleaning liquid through the valve and into the first fluid passage when the valve is in the second state. The valve is operated to cause the valve to move between the first state and the second state.