What to Do If Your Dehumidifier Gives Off a Musty Smell

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Dehumidifiers that are not properly maintained can give off unpleasant odors.
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Dehumidifiers are designed to remove excess humidity from your home, but if they are not properly maintained they can acquire a musty smell that spreads throughout your home. Problems start when the grills, bucket and air filter are not consistently cleaned; this causes bacteria and mold to accumulate. When there is enough buildup, the dehumidifier begins to smell musty and may even be less efficient. Cleaning your dehumidifier regularly and properly storing it are the best ways to keep this musty smell at bay.


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Cleaning the Exterior and Grills

While the exterior of the dehumidifier is not likely to cause a musty smell, if it is not cleaned regularly mold and bacteria can accumulate on the grill and potentially cause a smell or accumulate debris so that air cannot properly flow through the unit. Wash the exterior of the dehumidifier with warm water and a mild detergent. Vacuum any debris that has accumulated on the air intake and outtake grills with a small vacuum attachment or wire brush.


Cleaning the Bucket

The bucket is a likely culprit for a moldy smell arising from your dehumidifier. Unless you clean the bucket every several weeks, mold, bacteria and mildew can quickly accumulate. To clean the bucket, fill it half to two-thirds full with clean water. Add detergent until suds appear. Rotate the bucket to help the solution clean the sides of the bucket, empty it and rinse it with clean water. Do not use bleach in the bucket unless the manual for your particular brand and model explicitly states that bleach is safe to use.


Cleaning the Air Filter

Air filters should be cleaned once a month or more to prevent the accumulation of bacteria, mold and mildew that can cause a musty smell. Remove the filter from the unit and vacuum it gently with a vacuum attachment. Then scrub the filter gently with a sponge soaked with warm, soapy water. Rinse the filter in clean water and allow it to dry completely before replacing it in the unit.


Storing it Properly

Improper storage can cause biological growth inside the unit that creates a musty smell. This is often due to storing the dehumidifier with water still inside. To properly store your dehumidifier, turn it off and wait 24 hours; then empty the tank. Clean the exterior, bucket and filter as described above, allow the unit to fully dry and cover it in plastic to keep damp air out. Also allow the hose to drain completely. Some units may be flushed with a biofungicide prior to storage, but it must be safe for materials such as aluminum, polyethylene and copper that the units are often constructed of. To flush, take out the air filter and pour 2 cups of biofungicide into the reservoir; drain the biofungicide manually or by pressing the button that typically drains the unit. Avoid storing the dehumidifier in a basement or other damp location. Keep it in a dry area with good air circulation. Clean the unit again before you use it next.