Daily and weekly maintenance prevents the build-up of bacteria that can be dangerous to you and can breed in your home. A few simple household ingredients and a few minutes work will keep the bacteria at bay, and keep your Holmes humidifier working smoothly over the long term.
Cleaning
It is recommended that you remove the refillable water reservoir chamber and empty it of any stagnant water every day. Rinse it clean with warm water, wiping the interior down and then drying before refilling with cold tap water. Weekly, empty the reservoir and partially fill it with 8 oz. of undiluted white vinegar. Swirl the vinegar around the reservoir and scrub the walls of the interior with a clean sponge or bottle brush. Scrub with the vinegar both the valve that allows water into the chamber and the mist release nozzle (the interior and exterior). Rinse the water reservoir thoroughly and repeatedly with hot water.
If daily cleaning is inconvenient, add one or two drops of tea tree oil to the water reservoir when refilling; the oil will act as a natural bacteria-killer and run through the whole system. Tea tree oil will impart a slight but not unpleasant scent to the mist output.
Descaling
Depending on your model of humidifier, water may actually come into contact with the heating plate under the fresh water reservoir. Clean this space with the white vinegar solution and scrub off any built-up scale that can impair the humidifier's function. Allow the solution to soak into the plate or coils for 20 to 30 minutes if the scale build-up is very thick and is not readily dislodged. Rinse well and repeatedly with fresh warm water.
Replacing Filters & Wicks
Most newer models of Holmes cool humidifiers have either a filter that reduces mineral content in the reservoir water or wicks that aid in water uptake. The Holmes humidifier care guide recommends that these be replaced every two to three months or when scale build-up increases.