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. : e- K& O# O; X/ k I/ y2 w. h- R- b7 ?' j4 S# G( Q& Q7 K
Solution: turn off water supply and take the humidifier apart and clean it will stop the leaking. & c- Y, h- }3 z! d- H+ Y: {5 U* i6 h$ }
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Otherwise, find a professional or change a new set.