How to Deep Clean a Dehumidifier: Inside and Out

Why deep cleaning matters

A dehumidifier pulls moisture from the air, but it also collects dust, dirt, and mold spores. The warm, damp interior of a dehumidifier can become a breeding ground for mold if left uncleaned. The Centers for Disease Control and Prevention (CDC) notes that mold grows where there is moisture and can cause symptoms like a stuffy nose, wheezing, and skin rashes, especially in people with asthma or allergies. The U.S. Environmental Protection Agency (EPA) also emphasizes that the key to mold control is moisture control, and that mold should be cleaned up promptly.

A dirty dehumidifier works harder to move air and remove moisture. Dust on the coils acts as an insulator, reducing the unit's ability to condense water. Keeping the interior clean helps your dehumidifier run efficiently, which may also lower energy use. For information on how dehumidifiers achieve efficiency, see the guide on energy efficiency.

Safety first: unplug and protect yourself

Before any cleaning, unplug the dehumidifier from the wall. Never clean a plugged-in unit, especially around the fan and coils where electrical connections are exposed. Water and electricity are a dangerous combination.

When cleaning, wear protective gear. The University of Minnesota Extension recommends rubber gloves, eye goggles, and an N-95 respirator for mold cleanup. If you use a bleach solution, open windows and doors to provide fresh air. Never mix bleach with ammonia or other cleaners; this produces poisonous gas, as warned by the CDC.

Clean the bucket and drain pan

Start with the parts you can remove. Take out the water bucket and empty it. Wash the bucket with warm, soapy water, then rinse thoroughly. For disinfecting, the CDC recommends a solution of no more than 1 cup of household laundry bleach in 1 gallon of water. Apply it to the bucket, let it sit for a few minutes, then rinse and dry completely.

If your unit has a drain pan or a drip tray, clean it the same way. The drain pan collects condensate and can develop a musty odor or biofilm. For more on bucket odor and cleaning, see how to clean and deodorize the bucket.

Clean the coils and evaporator fins

The coils are the heart of the dehumidifier. They condense moisture from the air, but dust can build up and reduce heat transfer. Use a soft brush or a vacuum cleaner with a brush attachment to gently remove dust and debris from the coil surface and the fins. Work in the direction of the fins to avoid bending them. Be careful not to touch the coil with sharp objects.

Do not spray water directly onto the coils or any electrical parts. If the coils are very dirty, you can use a coil cleaning product designed for refrigeration equipment, but always follow the manufacturer's instructions. For a more detailed look at coil maintenance, read how to clean evaporator coils without removing them and internal coil cleaning.

Clean the fan and interior surfaces

The fan draws air through the unit, and its blades can collect a layer of dust. Use a vacuum with a narrow nozzle or a soft brush to remove dust from the fan blades and the fan housing. You may need to remove a protective grille to access the fan, but check your owner's manual first.

Wipe the interior walls and any visible surfaces with a damp cloth. Be careful around electrical connections and avoid soaking any components. If you have a permanent drain hose, check that it is clear and free of blockages. For more on fan maintenance, see fan cleaning and maintenance.

Reassemble and plan a regular schedule

Let all cleaned parts air dry completely before putting them back. This prevents mold from returning immediately. Reinstall the bucket, replace any filters, and plug the unit back in. Run it for a few minutes to confirm it operates normally.

How often you deep clean depends on your environment. In a dusty basement or a space with high humidity, you may need to clean every 2 to 3 months. In a cleaner space, twice a year is often enough. A good rule is to check the filter monthly and clean the internal components at the start and end of the humid season. For a complete maintenance routine, see the annual maintenance checklist.

If you notice heavy mold growth inside the unit that you cannot fully clean, or if the dehumidifier is more than a few years old and underperforming, it may be worth replacing it with a newer, more efficient model. Look for ENERGY STAR certified dehumidifiers or one suited to your space, such as a basement dehumidifier.

What to pick for easier maintenance

Questions

How often should I deep clean my dehumidifier?

Every 2 to 3 months in dusty or high-humidity spaces, and at least twice a year in normal home conditions. If you notice a musty odor or reduced performance, clean it sooner.

Can I use vinegar to clean the inside of my dehumidifier?

The CDC and EPA recommend soap and water, followed by a bleach solution for disinfecting. Vinegar is not a disinfectant for mold in the same way and may not kill all spores. Stick with the bleach solution for hard surfaces.

Is it safe to spray water on the coils while cleaning?

No. Water can damage electrical components and cause short circuits. Use a dry brush or vacuum with a soft brush attachment to clean coils. If you need a liquid cleaner, apply it to a cloth first, not directly to the unit.

I see black spots inside the bucket. Is that mold?

Likely yes. Mold can grow on any damp surface. Clean the bucket thoroughly with soap and water, then disinfect with a bleach solution (1 cup bleach per gallon of water). Rinse and dry completely before replacing.

Do I need to wear a mask while cleaning a dehumidifier?

The University of Minnesota Extension recommends an N-95 respirator when cleaning moldy surfaces to avoid inhaling spores. Wear gloves and goggles as well, and ventilate the area if using bleach.

What should I do if the inside of my dehumidifier is heavily moldy?

If the mold covers a large area or the unit is old, you may not be able to clean it thoroughly enough. Consider replacing the unit. For moderate mold, follow the cleaning steps and ensure the area around the dehumidifier stays below 50% humidity, as recommended by the CDC.