dehumidifier smells musty

Dehumidifier Smells Musty?

Does Your Dehumidifier Smell Musty?

Musty is a word that describes the smell of mold.

When your dehumidifier smells musty, it is almost more than certain that it has mold and bacteria growing in the water or the filter and you need to give the whole unit a thorough disinfecting.

Dehumidifiers like their cousin, the humidifier have a predisposition for becoming moldy because of standing water.

And dehumidifiers even more so.

dehumidifier is moldy


1.  The Dark

The fact that dehumidifiers are collecting water into a basin that is dark makes them more likely to grow mold and bacteria even faster. Low light and dark are essential for mold to grow.

2. Collect airborne contaminants

Dehumidifiers also have the added component of removing airborne germs like bacteria, molds, spores, and pollen from the air which go into the water tank and are allowed to grow and populate till the tank is emptied and cleaned.

3.  Not visible

Unlike a humidifier that usually has a clear basin that you can see the water and get a visual idea of whether it is getting dirty, dehumidifiers collect water into a bucket that you cannot see.

And in this case, out of sight, out of mind, can mean that mold and bacteria can get a stronghold.

With all this in mind you can see that a dehumidifier has an even greater predisposition to growing bacteria and mold inside of the water than a humidifier.

This is a very serious situation when it is not taken care of in a timely manner.

Inhaling bacteria that has grown on water can make you very sick.

Legionnaires disease and Pontiac fever to a lesser degree or diseases that are caused by breathing in water grown bacteria.

Legionnaires disease is responsible for death in many people, especially the elderly and people with weakened immune systems.

Whether you’re talking about a dehumidifier, a humidifier, or an evaporative cooler, these types of appliances are prone to becoming germ farms.

And they all require a stricter attention to keeping them clean because of that fact.


There is one caveat to helping you keep a dehumidifier cleaner longer. That is to run a continuous hose from it so that the water does not collect in the dehumidifier but goes outside.

But regardless, even with the continuous hose, they need to be cleaned often to ensure that they are kept safe and healthy.

how to clean a dehumidifier

How to Clean Your Dehumidifier

Routine cleaning of the dehumidifier is essential for keeping it from developing germs and bacteria and also for running efficiently.

The main components that you want to dial in on when cleaning a dehumidifier are:

  • The water basin
  • The filter
  • The coils
  • outside

1. The water basin

Arguably the most important part of cleaning a dehumidifier is keeping the water basin and around it disinfected.

Bacteria can begin to grow in water in as little as 48 hours. And since dehumidifiers have all the criteria; low light, dust, and moisture, for mold to flourish,
Special attention should be given to the water basin to ensure that it is kept clean and disinfected thoroughly and often.

Fortunately it’s not a tough job.

a. unplug the machine

No use risking the chance of being shocked regardless.

To clean the water basin on your dehumidifier, simply take the basin off and dump the water out.

Using cleaning vinegar, which is a little more acidic than regular white vinegar, completely scrub out the basin and rinse it.

Add a couple of cups of vinegar back into the basin and fill it up. Allow it to sit for at least 30 minutes.

Dump the vinegar out, rinse it out with warm water and allow it to completely dry.

2.  The filter

Dehumidifiers are almost identical to window air conditioners in their mechanics.
And if the filter is allowed to get dirty enough to inhibit the airflow, the machine will not do its job properly.

To clean the filter, simply pull it out and knock off the loose material into the trash.

To take a cleaning brush and scrub the rest of the debris out of the filter.

Knock it off again, into the trash.

At this point, if the air filter is particularly dirty, canned air can be used to blow the filter out even further.

And if it’s still grimy after that, wash it under the faucet using warm water.

If you end up having to clean the filter with water, be careful to let it dry completely before you reinsert it.

Since water is one of the components of mold taking root.

3. The coils

The coils are less likely to be dirty and are not considered an essential part of routine maintenance. But they can still get dirty over time.

If the coils on your dehumidifier or window AC get dirty. The machine will not run as efficiently and use more energy.

Dirty coils can also cause the machine to freeze up quicker.

To clean the coils, a can of coil cleaner can make the job very easy.

Coil cleaner foams up similar to bathroom cleaner. Simply spray the coil cleaner all over the coils, let it foam up and sit.

After it has sat for the amount of time that the direction says, wash the coils off with warm water, preferably with the spray bottle, and let it completely dry.

4. Outside

Wipe the outside thoroughly with cleaning vinegar. Sure to get into the nooks and crannies where water can get access to and eventually cause bacteria to grow on the outside of the machine.


Does the dehumidifier smell musty?

A musty smell is almost always certainly an indication that there is mold somewhere in the vicinity.

When you smell that mustiness coming from your dehumidifier, then the most logical reason is that it has mold and bacteria growing or starting to grow in the water or even around the water basin.

Since dehumidifiers pull moisture out of the air that is filled with bacteria and allergens like mold spores and dust mites,

The moisture that is collected inside of the dehumidifier has a chance of developing mold and bacteria even faster than just standing water on its own.

And you couple that with the fact that it is dark inside of the basin, you have all the ingredients for mold and bacteria to take root faster.

Bacteria growing on standing water can be dangerous to breathe.

Legionnaires disease is caused by inhaling a certain bacteria that has grown on water.

So keeping the water basin emptied and thoroughly cleaned on a dehumidifier is very important.

Fortunately it’s a job that you can do with some household items like a scrub brush and some vinegar.

   And if the area where you have your dehumidifier can accommodate it, you can skip the water basin all together and hook up a continuous hose. So that the water coming into the machine goes outside instead of collecting into a bucket.


Published by

Dennis Reed

Dennis Reed Owner and Author @