A tank is installed in a liquid consuming apparatus having a liquid consuming unit and is connected to the liquid consuming unit. The tank includes: a casing having a bottom wall and a side wall in a usable posture of the tank, the side wall extending in a direction intersecting the bottom wall; a first storage chamber and a second storage chamber provided in the casing and configured to store the liquid; an inlet provided to inject the liquid into the first storage chamber; a first communication port that communicates the first storage chamber and the second storage chamber; a second communication port provided in the second storage chamber to let the liquid flow out to an outside of the tank; and an air opening port that opens the first storage chamber and the second storage chamber to the air.