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. $ ~" V p" y$ c
/ x( } k: l2 \0 m
Solution: turn off water supply and take the humidifier apart and clean it will stop the leaking. 3 F( ], [4 @/ t : m6 o2 f3 ]: U/ T$ o8 ?4 J1 V( G& h$ t: A- D1 v' h5 k# f9 X
Otherwise, find a professional or change a new set.