A water fullness alarm device may include an alarm switch, a bracket, and a float. The alarm switch may include an alarm switch body and a switch button disposed on the alarm switch body, where the switch button is adjacent to an elastic piece, and where a first end of the elastic piece is fixed on the alarm switch body and a second end of the elastic piece is free. The bracket may be rotatable, where a first end of the bracket is connected with the float, and where a second end of the bracket is propped against the elastic piece. The first end and the second end may be integrally formed such that the second end swings synchronously with the first end around an axis when the bracket rotates, where the second end drives the elastic piece to trigger the switch button when the bracket rotates.