Clean your dehumidifier every two weeks during heavy use
A dehumidifier pulls moisture from the air through a cold coil, and dust, pet hair, and mold spores stick to that coil. If you don't clean it regularly, the coil clogs, the machine works harder, and it pulls less moisture from the room. Cleaning takes about 15 minutes and requires only a soft brush, a vacuum, and warm water. Most of the work is emptying the water tank and rinsing the filter—the parts you touch most often anyway.
How often you clean depends on how much the dehumidifier runs. If it's running eight hours a day in a damp basement, clean it every two weeks. If it runs a few hours a day in a bedroom, once a month is enough. If the air in your home is very dusty or you have pets, move toward the two-week schedule.
Key Takeaways
- Empty the water tank and rinse the filter every time the tank fills, or at least every two weeks during heavy use.
- Vacuum the intake vents and brush the cold coil gently with a soft brush to remove dust and mold growth.
- Never pour water directly on the coil or electrical parts—use a soft brush and compressed air instead.
- Replace the filter according to the manufacturer's schedule, usually every three to six months, depending on how dusty your home is.
- If you see mold on the coil or smell mold from the machine, clean it when ready and check for leaks or standing water nearby.
Empty and rinse the water tank
The water tank is the easiest part to clean and the one you'll do most often. Unplug the dehumidifier, slide out the tank, and pour the water down a sink or drain. Rinse the inside of the tank with warm water and wipe it dry with a cloth before sliding it back in.
If the tank smells musty or you see black spots inside, soak it in a mixture of one part white vinegar to three parts warm water for 15 minutes, then scrub with a soft brush and rinse thoroughly. Dry it completely before reinstalling it, because standing water in the tank breeds mold.
Vacuum the intake vents and filter
The intake vents are where air enters the machine—usually on the side or back. Dust builds up here first. Unplug the dehumidifier and use a vacuum with a brush attachment to gently remove dust from the vents. Don't push hard; you're brushing away surface dust, not forcing the vacuum into the opening.
Next, locate the filter. On most dehumidifiers, it's a foam or mesh panel behind the intake vents or inside a removable cover. Slide it out and vacuum both sides gently with the brush attachment. If the filter is very dusty, rinse it under warm running water, squeeze out excess water (don't wring it), and let it air-dry completely before putting it back. Never run the machine with a wet filter.
Brush and inspect the cold coil
The cold coil is where the actual dehumidifying happens—moisture condenses on it and drips into the tank. It's also where mold and algae grow most easily. To reach it, you may need to remove a front panel or access cover; check your manual for the exact location and how to open it safely.
Once you can see the coil, use a soft brush—an old toothbrush works well—to gently brush away dust and any visible mold or algae. Brush in the direction the fins run, not across them. If the coil is very dirty, use a can of compressed air held upright, spraying short bursts from a distance of six inches. Never pour water on the coil or spray it with a hose; water can seep into the electrical components and damage the machine.
If you see heavy black or green mold on the coil, the dehumidifier is running in a very damp space. Clean it now, but also check for standing water, leaks, or poor drainage in the room itself. Mold growth this heavy means the humidity is not dropping enough, even with the machine running.
Replace the filter on schedule
Filters wear out and stop trapping dust effectively. Check your manual for the replacement schedule—most dehumidifiers need a new filter every three to six months, depending on how dusty your home is. If you have pets or live in a very dry climate where dust is heavy, replace it every three months. If the air is cleaner, six months is fine.
When you replace the filter, note the model number of your dehumidifier and order the correct replacement. Using the wrong filter size or type means air bypasses it, and dust reaches the coil faster. Filters are inexpensive—usually between $15 and $40—and replacing them on time extends the life of the whole machine.
Clean the exhaust vent and drain line
Water leaves the dehumidifier in two ways: through the tank you empty by hand, or through a drain hose if your machine has a continuous drain option. If your dehumidifier has a drain hose, check it monthly for clogs. Disconnect the hose from the machine and the drain point, and flush it with warm water. If water doesn't flow freely, use a plumbing snake or a straightened wire coat hanger to clear the blockage.
The exhaust vent—where dry air leaves the machine—can also collect dust. Wipe it with a dry cloth or use compressed air to blow dust away. A clogged exhaust vent makes the machine work harder and reduces how much moisture it removes.
Wipe down the exterior and check for leaks
Once a month, unplug the dehumidifier and wipe the outside with a dry cloth to remove dust. Pay attention to the top and sides where dust settles. If you see water pooling under the machine or dripping from seams, the tank may not be seated properly, or the drain hose may be kinked or loose. Check that the tank is pushed all the way in and that any drain hose is straight and connected firmly.
If water continues to leak after you've checked the tank and hose, the machine may have a crack or a failed seal inside. At that point, it's time to call the manufacturer or consider replacing the unit, because internal leaks usually mean the machine is failing.
Frequently Asked Questions
Can I use bleach to clean mold off the coil?
No. Bleach can corrode the aluminum fins on the coil and damage the machine. Use a soft brush and white vinegar instead. Mix one part vinegar to three parts water, dip the brush in the mixture, and gently brush the coil. Rinse with a dry cloth and let it air-dry before running the machine again.
What if water is leaking from the bottom of the machine?
First, make sure the tank is fully seated—slide it out and back in firmly. Check that the drain hose (if you have one) is not kinked or disconnected. If the tank is in place and the hose is clear, the seal inside the machine may be failing. Stop using it and contact the manufacturer, because continued use can damage the electrical components.
How do I know if the filter needs replacing before the scheduled time?
If you notice dust collecting on the intake vents faster than usual, or if the machine is running but not removing as much moisture, the filter may be clogged. Hold it up to a light—if you can't see light through it, replace it. A clogged filter forces air through gaps around the edges instead of through the filter itself.
Is it normal for a dehumidifier to smell musty?
No. A musty smell means mold is growing inside, usually on the coil or in the tank. Clean the tank with vinegar and water, brush the coil gently, and make sure the filter is dry before reinstalling it. If the smell returns quickly, the humidity in the room is too high for the machine to handle, or there's a moisture source nearby that needs attention.
Can I run the dehumidifier while I'm cleaning it?
No. Always unplug the machine before opening it, removing the tank, or accessing the coil. Water and electricity don't mix, and you could damage the machine or hurt yourself. Wait until all parts are dry before plugging it back in.