An ink cartridge that has a rigid housing. The housing has a docking face for abutting a printer such that, when installed, the docking face faces downwards. The cartridge also has an ink storage volume and an ink outlet valve for fluid communication with the printhead. The ink outlet valve and an air inlet are both being positioned in the docking face. A variable volume structure within the ink storage volume inflates with air as ink is drawn from the outlet. The variable volume structure has a section that displaces upwardly within the ink storage volume as it inflates with air. An air inlet spaced from the outlet valve is in fluid communication with the variable volume structure to lets air into the ink storage volume as ink is drawn out through the outlet valve. A conduit in the ink storage volume is connected to the ink outlet valve at one end, with the other end being open to ink within the ink storage volume. The other end is positioned remote from the docking face such that it does not get obstructed by the variable volume structure as the variable volume structure inflates.