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. 7 \$ D/ j& Y$ K1 [2 M" S! o 5 Y4 F0 D3 h, R" g9 ?Solution: turn off water supply and take the humidifier apart and clean it will stop the leaking. ( E4 s0 L' }8 p" S1 ?' p/ N2 q0 i 8 h7 m) y( D# D; [" L * o" L6 x. \6 B' I1 S8 m7 t8 AOtherwise, find a professional or change a new set.