Check the dehumidifier. Most models have an indicator light that lights up or blinks if the dehumidifier water reservoir is full. If your model does not have an indicator light, open the door leading to the bucket to check water levels.
Open the side door leading to the dehumidifier's water reservoir if the model is not self-draining. If the model is self-draining, it will need to be attached to a drainage system that will empty the water bucket.
Slide the water bucket out of the dehumidifier carefully so as not to displace any of the water.
Empty the water into an area with a drain or outside.