Turn off and unplug the humidifier.
Lift the water reservoir off of the humidifier base and set it aside.
Empty the base into the sink.
Fill the base with a mixture of 1 cup of white vinegar mixed with 1 gallon of water. Allow it to sit for 20 minutes.
Empty the vinegar solution into the sink. Scrub the interior parts with a soft brush. Dampen a cloth with white vinegar and wipe the base to remove scale. For small areas, use the cleaning brush included in the base. Pay special attention to the transducer located above the base.
Dampen a cloth with water and wipe the base, transducer and all other parts that were cleaned with vinegar.
Dry the base with a cloth and replace the water reservoir.
Turn off and unplug the humidifier.
Remove the water reservoir from the humidifier base.
Fill the base with a mixture of 1 teaspoon of bleach per gallon of water. Allow it to sit for 20 minutes. Swish the bleach mixture around the base every few minutes to cover all surfaces.
Empty the bleach mixture from the base into the sink and rinse it thoroughly with clean water.
Dry the base with a cloth and replace the water reservoir.