It is possible that the shut-off valve was blocked by the cumulated white stuff. As a result, water supply can not be stopped even when water level is high. # N4 M: A* U/ j& w1 V* A( C, C/ f, {2 U1 ~, y% @
Solution: turn off water supply and take the humidifier apart and clean it will stop the leaking. {, T# ]1 x. R) D9 I' ^% ^
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Otherwise, find a professional or change a new set.