An ink supply arrangement for an inkjet printhead is provided having at least one collapsible ink bag containing ink for distribution to nozzles of the printhead via a fluid path between the ink bag and nozzles, a body for housing the ink bag and the printhead, and a biasing member in the ink bag. The ink is primed in the fluid path and nozzles so as to be ejected by the nozzles, in use, thereby depleting the ink contained in the ink bag. The ink bag is attached to the body at a wall opposite a wall of the ink bag facing the printhead. The biasing member applies outwardly directed force on the wall of the ink bag facing the printhead thereby maintaining substantially constant negative pressure at the nozzles as the ink is depleted. The fluid path connects the ink bag to at least 6400 nozzles of the printhead.