A fluid tank has a housing that has an upper end wall, a side wall, and a lower end wall that together define a cavity. A flexible diaphragm is connected to the side wall within the cavity and separates the cavity into an upper portion, which is sealed to contain a pressurized gas, and a lower portion, which is sealed to contain a pressurized fluid. An indicator is positioned in the upper wall of the housing and has an indicator arm and a visual indicator. The indicator arm is not visible and the visual indicator is visible with the indicator in a first position and the indicator arm is visible and the visual indicator is not visible with the indicator in a second position.