(1) Check whether the water level is higher than the float ball at the bottom of the Clean Water Bucket.(2) A water level lower than the float ball is normal. Currently the sensor is set such that the user will be prompted to add water if the water level is lower than the float ball.(3) If the water level is obviously higher than the float ball, please lift the Clean Water Bucket and put it back in.(4) If the alarm persists, please gently touch the float ball to check whether it is stuck.① If the alarm is gone after you touch the float ball, you can use it as usual.② If the float ball won't move or the alarm persists after you touch it, please contact customer service.