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 W k4 F( J& n/ ~& w" M4 [. ?; A. R( }$ ]/ I7 L$ M# \
Solution: turn off water supply and take the humidifier apart and clean it will stop the leaking. - [8 n3 H1 Q* g, _8 x0 F' Q 4 p f6 A. ]4 G! y6 d" P! Y9 o3 c" {+ K
Otherwise, find a professional or change a new set.