Switch off the humidifier before beginning any cleaning procedure. Unplug the unit from the wall after you've turned it off.
Lift off the main housing. The main housing contains the motor unit, which must not get wet, so place the main housing in a dry area away from where you will be doing the cleaning.
Slide the PermaWick Filter out of the main housing. Release the plastic hooks you'll find at each corner of the filter frame, and remove the filter from its frame.
Place the filter in a basin or a large sink. Fill the basin with 1 gallon of water and 1 cup of white vinegar. Let the filter soak for 20 minutes.
Remove the filter from the vinegar solution and rinse it thoroughly with cool water. Prop it up over a towel and allow it to drip dry while you clean the rest of the humidifier.
Take the water tank out of the base. Empty any remaining water in the tank.
Mix 1 gallon of water with one cup of white vinegar. Pour this solution into the base and let it sit for 20 minutes.
Empty the vinegar solution out of the base. Wipe it with a sponge or cloth to remove any remaining mineral deposits, then rinse it with clean water.
Pour 1 gallon of water and 1 cup of white vinegar into the water tank. Replace the cap on the tank and shake it thoroughly until the vinegar-water mixture has cleaned off the inside surface of the tank. Empty out the vinegar-water solution and rinse the water tank out with clean water.
Use a soft cloth to wipe off the main housing. Reassemble the humidifier and refill the tank with water up to the "fill" line. Plug it in, turn it on and resume use.