Provided is an aircraft water tank with a lid joined to an opening portion via internal threads and external threads. An O-ring is compressed so that the opening portion is liquid-tightly sealed, which forms a sealed water storage space in a tank body. The portion of the lid that compresses the O-ring is a corner portion formed by an end surface of an annular plate portion and an outer peripheral surface of a tube portion. The portion of an inner liner that compresses the O-ring is a portion of the inner liner attached to an inclined surface. An end portion of the inner liner attached to the surface of a bulging portion is located outside the water storage space.
