Humidifier Makes Room Smell Musty

If you have noticed a musty or moldy smell in your home, there is a high likelihood that the humidifier level in certain parts of your home is very high. Using a humidifier when your indoor humidity is already high will definitely make your home smell musty.

A humidifier can only make a room smell musty when the humidifier is used in a room with high humidity levels that exceed the recommended 40 to 50% recommendation for indoor humidity.

If you want to continue enjoying the benefits of having a humidifier in your home without worrying about mold and other microbes that grow in high-humidity areas, this article will offer you some insights into the different factors that raise indoor humidity or promote the growth of mold in a home.

Equipping yourself with a little bit of knowledge and the right approaches for managing your indoor space, will help you keep your humidifier from making your room smell musty.

In this post we will cover the following:

Humidifier Makes Room Smell Musty

Humidifier Makes Room Smell Musty

When a humidifier is not maintained properly or cleaned regularly, mold and bacteria can start growing in the humidifier’s water tank, thereby placing you and your loved ones at risk of developing mold-related illnesses like allergies.

The mold that accumulates in a humidifier can lead to the development of a musty or unpleasant smell inside the humidifier and in the room where you commonly use the humidifier.

Aside from that, if you are using a humidifier that is not the correct size for your room or house, especially in cases where a large humidifier is used in a relatively small room, the moisture released from the humidifier can easily increase your indoor humidity to excessively high levels, leading to over-humidification of a room.


Cleaning: To prevent the musty smell from taking over your room or accumulating in your humidifier, it is important to regularly clean and disinfect the device.

A quick and easy way of keeping your humidifier clean is using a half-and-half solution of water and vinegar to clean the humidifier or using water and hydrogen peroxide.

If you opt to use water and hydrogen peroxide to clean your humidifier, ensure that you rinse the humidifier’s water tank well to remove all traces of hydrogen peroxide.

Empty and Refill: Aside from just cleaning your humidifier, it is also important to empty and refill the water tank daily, and to use distilled water to prevent mineral buildup.

Replace: If you notice that the humidifier continues to produce a musty smell despite regular cleaning and maintenance, you should consider replacing the device or asking a professional to take a quick look at it to determine the problem.

In some cases, water might have seeped into some of the internal areas of the humidifier and promoted the growth of mold in hard-to-reach areas. A professional plumber or electrician can open the humidifier and clean it thoroughly for you.

Can A Humidifier Make A Room Smell?

Mold growth in the humidifier: Yes, a humidifier can make a room smell bad depending on the quality of water placed in the humidifier. For instance, using tap water has been linked to increased risks of mold growth in humidifiers by numerous research.

In our experiments, we have also found that tap water can contain minerals, dust mites, dirt, dust, and other contaminants that can provide mold and other microbes with the perfect environment and nutrition that will promote mold growth in your humidifier.

This is why most manufacturers recommend using distilled water in humidifiers as distilled water does not contain contaminants that can alter the natural scent and microbial activity rate within your home.

Mold growth in your home: You might be using your humidifier properly but still notice that your room smells bad. The humidifier may be adding excess humidity to your indoor space. If your home has too much humidity, the air in the room can get musty and stuffy.

Check the humidity level in your home before turning on your humidifier to determine whether or not you should be running your humidifier.

If the humidity levels are above 55% RH, you should not use a humidifier. If the humidity level is between 50 and 55%, you should use your humidifier with caution and monitor your indoor humidity levels regularly.

You can invest in a hygrometer to help you assess the humidity levels in your home. Check out the two recommended options below from Amazon:

Common Causes Of Musty Smell In A Room With A Humidifier

Some of the most common causes of a musty smell in a room include:

  • Too much humidity in the room: High humidity levels provide a breeding ground for mold and other microbes that can make the indoor air musty.
  • Poor maintenance of the humidifier. Not cleaning a humidifier regularly will promote the accumulation of mold and dirt in the humidifier and also contribute to moldy or musty smell, as the contaminated water is dispersed into the surrounding environment.
  • Water leaks and damaged walls. Water leaks caused by damaged pipes and cracks in walls can also promote the growth of mold, which can, in turn, cause musty smells in your home.
  • Using tap water that contains minerals or impurities in the humidifier. The impurities in tap water can contribute to unpleasant smells, which can be confused with mold growth.
  • Using a humidifier that is too big for the size of the room. If you are humidifying a small room, it is essential to use a small portable humidifier or limit the number of hours that you use a medium-sized or large humidifier.

How To Prevent Musty Smell In A Room With A Humidifier

  1. Maintaining your indoor humidity at the right or recommended levels (40-50% is generally safe). Anything past 55% is considered a high humidity level.
  2. Cleaning, disinfecting, and maintaining the humidifier regularly and according to the manufacturer’s instructions. If you disposed of the manufacturer’s manual or box that the humidifier came in, you can follow the cleaning guideline discussed above.
  3. Using distilled water or purified water in the humidifier prevents the build-up of dirt, minerals, and contaminants.
  4. Using the appropriate size humidifier for a room to prevent over-humidification of your indoor space.

How Do You Get The Musty Smell Out Of A Humidifier?

A humidifier should be cleaned and disinfected to remove the musty smell. You can easily clean and disinfect your humidifier according to the manufacturer’s instructions, which usually suggest using a water-and-vinegar or water-and-peroxide solution and rinsing the humidifier with some distilled water afterwards.

It is also crucial to use distilled water for humidification to avoid mineral deposits accumulation in the humidifier and to empty and refill the water tank every day.

Additionally, you should replace the humidifier if the musty smell continues after routine cleaning and maintenance because continued of a humidifier that is filled with mold can increase your risk of illness. 

Make sure the humidifier is the right size for the space it will be used in. Using a humidifier that is too big will result in too much moisture and a musty odor.

Prevention: A prevention technique that you can apply afterwards is ensuring that you always empty your humidifier and dry the water tank when not in use to prevent the growth of mold and retention of unpleasant smells.

Why Does My Room Smell Musty?

Numerous issues can be the cause of musty or unpleasant smells in your home. Some of the most common causes of musty smells include mold growth, poor ventilation, wetness or dampness, and lingering odors from daily household activities like cooking, smoking, and indoor laundry.

Check your room carefully to determine the cause of the musty smell. You can also try airing out your room by opening your windows and doors if the weather outside is favorable.

Alternatively, you can also clean your room from one end to the other to ensure that any dirt, forgotten food cans and boxes, or dampness are handled.

Related: Can Using a Humidifier Cause Mold


Musty smells in a room can be caused by a wide range of factors. If you suspect that your humidifier is the cause of the musty smell in your home ensure that you check the humidity levels in your room first, then switch off the humidifier if the humidity level is above 50 or 55% RH.

Note that your humidifier can also be the cause of musty smells in a room if the humidifier is not cleaned well regularly or if you do not use the right type of water in your humidifier.

As such, you should always clean your humidifier properly and use distilled water to reduce the risks of mold growth and dirt accumulation in the humidifier.