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. . z/ ~$ P. f. x* e6 P/ H
: P1 g) I3 d' ~! P0 y1 bSolution: turn off water supply and take the humidifier apart and clean it will stop the leaking. ) o( x4 y' f& N9 l) S# B9 {0 r! J5 _4 f m v0 Q
! d X% K# C' i- nOtherwise, find a professional or change a new set.