Why Does My Humidifier Make My Room Smell Bad? Causes and Fixes

If your humidifier makes the room smell musty, well, something is wrong. The same way that a Pure Enrichment humidifier not working is cause for worry, so will any humidifier that makes your room smell musty.

Usually, the humidifier will start working just fine, but after some time, it will start producing mist with a musty smell. While this is better than a humidifier not producing mist, well, you need to know what causes it, and rectify the problem as soon as possible.

So, what are the main reasons why a humidifier would produce mist that has a musty smell? Mold? Dirt? Bacteria? Combination of all of these?

Keep reading to find out!

10 Possible reasons for a humidifier making your room smell musty

humidifier making your room smell musty

A humidifier will save you from the effects of sleeping in dry air. But like everything else, these humidity control devices have their flip side. For instance, in my post on a Levoit humidifier not working, you saw tens of reasons why this device can fail.

Today, we look at the main causes of a humidifier making a musty-smelling mist:

1. Water has stayed too long in the tank

Remember that delicious bowl of soup you forgot about in the fridge? Same idea! Humidifiers hold water, and if it sits for too long, it gets stagnant.

This stagnant water becomes a breeding ground for yucky bacteria and black mold, which release those musty smells.

Solution: Pour out the old water, clean the humidifier tank with soap and water, rinse it thoroughly, refill it, and reattach it.

2. Minerals in the tank

Do you live in a place with “hard water”? This water has lots of minerals that can build up inside your humidifier, leaving white crusts and contributing to that musty odor. You can tell you have hard water if your ultrasonic humidifier leaves white dust.

Solution: Clean the tank, the base, and the heating elements if it is a warm mist humidifier. Follow the same instructions for cleaning in this post on how to clean a Levoit humidifier.

3. Filters replacement is long overdue

Just like air filters in your house, humidifier filters need regular cleaning or replacement. A clogged filter traps dust, dirt, and even more yucky stuff, which adds to the musty mix. It can trap mold, releasing musty-smelling air back into the room.

Solution: If it comes with washable filters, clean them under running water, and air-dry on a rack completely before refitting them.

4. Wick problems

Some humidifiers have wicks that absorb water and release it into the air. These wicks can trap mold and mildew, especially if not dried properly after use. Guess what that smells like? Bad, really bad.

Solution: Clean or replace the wick. Just clean it in warm water and mild soap, but sometimes a dip in white vinegar can also help.

5. Dirty air ducts

If your humidifier uses air from your house, those musty smells could be coming from dusty air ducts! The humidifier just amplifies them like a smelly amplifier.

Solution: The same way you would have a professional technician check the whole house humidifier, have them check the air ducts too.

6. You added essential oils

Did you add essential oils to your humidifier? While they might seem like a good idea, some can damage the humidifier and trap smells inside, leading to, you guessed it, mustiness!

Solution: Clean the humidifier thoroughly, and unless it has a scent pad, never add essential oils to the tank. You can even use a Vicks humidifier without Vapopads if that is the issue.

7. Plastic smell

Some cheap humidifiers are made of low-quality plastics that can release unpleasant odors, especially when heated. Usually, the humidifier has a plastic smell that lingers in your air.

Solution: It will stop smelling soon, or you can invest in a good-quality one if you can.

8. Placing humidifier at a questionable location

Where to place your humidifier matters! Placing it near dusty areas, furniture, or closed windows can trap bad smells and make them worse.

Solution: Leave a space of at least 12 inches between a humidifier and the wall, or furniture.

9. Keeping the indoor temperature too low

Keeping your house too cold can slow down evaporation in the humidifier. This leads to stagnant water staying too long in the unit, thus producing an unwelcome odor.

Solution: Never use the same humidifier water for three consecutive days. If the water in the tank is not being used up, check the hygrometer. You probably don’t need to be using the humidifier.

10. You did not clean the humidifier

Forgetting to clean your humidifier regularly is a recipe for mustiness. A dirty humidifier can also cause bacteria growth, pink mold in the tank, and other shenanigans.

Solution: Clean your unit two times a week, or sooner if you use it daily. 

How to get the musty smell out of your humidifier

How to get the musty smell out of your humidifier

Getting rid of the musty smell is fairly simple. Here’s how:

Empty and clean: This is the most important step! Empty the water tank regularly and clean it with white vinegar or a mild cleaning solution. Don’t forget the filter and wick, following the manufacturer’s humidifier instructions.

Dry it thoroughly: After cleaning, dry all parts completely before reassembling.

Fresh water: Use fresh, filtered water instead of tap water in the humidifier to minimize mineral buildup.

Filters: Clean or replace your filter regularly, following the manufacturer’s instructions.

Can I make my humidifier smell nice?

Yes, you can, indeed. Start by using distilled water in the unit.

While adding scents isn’t the best idea for most humidifiers, there are safe alternatives:

Citrus: Place a few slices of lemon or orange in the water tank for a natural, refreshing scent.

Herbs: Add a few sprigs of fresh herbs like rosemary or mint for a subtle, calming aroma.

Clean it: Regularly cleaning your humidifier is the best way to ensure it emits only clean, fresh air.

Frequently Asked Questions

Can the musty smell from the humidifier make me sick?

While not typically dangerous, mold and mildew growth in your humidifier can trigger allergies or respiratory problems for some people. So yes, a humidifier can make you sick. Regular cleaning is key!

How often should I clean my humidifier?

Ideally, clean it daily if you use it frequently. If you use it just a few times a week, cleaning it at least once a week is essential.

What if the smell still lingers after cleaning?

If the smell persists, there might be hidden mold growth. Consult the manufacturer or consider replacing the humidifier.

Can I use bleach to clean my humidifier?

No! Bleach can damage your humidifier and release harmful fumes. Stick to white vinegar or mild cleaning solutions.


Always remember that a clean humidifier is a happy humidifier! By understanding the reasons behind the musty odor and following these simple cleaning tips, you can keep your humidifier running smoothly and enjoy the benefits of fresh, moist air without holding your nose anytime you step into the room.