Do Humidifiers Cause Mold? 3 Big Problems Caused By Humidifiers

Indoor Air Quality

Mold in a home is not only an eyesore with a musty smell but a major health hazard. Nearly 4.6 million asthma cases in the US are associated with mold exposure. Mold-related illnesses don’t come cheap either. The yearly cost of allergic rhinitis caused by high humidity and indoor mold is $3.7 billion!

It is a well-known fact that mold LOVES humid places. Naturally, you worry if your trusty humidifier, which increases the humidity in your home in the colder months, is causing mold growth. But is your concern legit? 

Do humidifiers cause mold in your home? How dangerous is the spread of mold spores to your family’s health? Most importantly, what can you do so that your humidifier won’t turn against you and invite the enemy mold into your house?

Read the answers to these questions and more in the following article.

DP do humidifiers cause mold

Do Humidifiers Cause Mold?

Humidifiers can cause mold if they raise the humidity too high. If the humidity level in a home is not being managed properly and it increases to 70% and above, mold will prosper and spread.

A humidifier, if not appropriately used and regularly maintained, can cause these three problems:

  1. Promote the growth of allergens. The high humidity level in itself can cause allergic rhinitis or hay fever. But other allergens such as mold, dust mites, cockroaches, and other small insects thrive in an overly humid environment. It is also easier for allergy triggers to float and stay in the air when it is heavy with moisture. Overuse of a humidifier causes mold and other air pollutants to ruin the indoor air quality of your home.
  2. Trigger and worsen asthma attacks. While the right level of humidity produced by the humidifier can ease asthma symptoms, a humidity level above 50% can prompt asthma attacks. It can even make the breathing of the sufferer more difficult. Because the air is denser and more stagnant when there’s too much vapor, mold, mildew, bacteria, and viruses have a greater chance to develop and induce asthma symptoms.
  3. Cause damage to furniture. Your health is not the only thing in jeopardy when the humidity level caused by your humidifier is out of control. Wood furniture, for example, is porous and absorbs water easily and deteriorates. Mold will then feed on the damaged furniture and cause health problems and structural harm to your home. 

Small room humidifiers tend to be the most dangerous. If you have several portable humidifiers in different rooms, you may be unable to track if the water has been replaced or if all tanks have been cleaned. Mold growth can start to form inside a small humidifier in two days. 

If the room humidifier is also placed too close to walls and furniture, it can release too much condensation on surfaces and damage its wood components, making it a likely food for mold. 

Central or whole-house humidifiers have better control and are safer. Typically installed and tucked away with your air conditioner and heating systems, it is out of your way. You can also better manage the humidity level in your home with a central humidifier and prevent over-humidification. Cleaning and maintenance of whole-house humidifiers are also less than room humidifiers.

How to Prevent Mold Growth With Your Humidifier

The ideal relative humidity is at a 30% to 50% moisture level. A humidifier is designed to increase the humidity in your home by releasing water vapor. It is found to ease congestion, asthma symptoms, dry skin, and nasal cavities, and also help with sore throats.

While there is a certain need for humidifiers during the colder months when heating systems make the air so much drier, it is critical to strike a balance. Too much humidity can give birth to another set of problems. 

One leading issue is mold growth. It is no secret that molds flourish in damp surfaces and moist spaces. Of course, you cannot just stop using humidifiers only to prevent mold growth. 

So how can you prevent mold from developing inside your humidifier and stop it from spreading around your home? Here are a few effective tips to take note of:

Clean Your Humidifier Regularly

Because a humidifying unit is always damp, a dirty humidifier may quickly become home to mold. It is best to establish a rigorous cleaning program for your humidifier to maintain good air quality for your home.

  1. Wash the humidifier components with clean water and vinegar.
  2. Let the mixture sit for 20 minutes while occasionally swishing the water inside.
  3. Empty the tank from the solution and rinse it with clean water until the vinegar smell is gone.
  4. Every week, perform a deeper cleaning routine on the tank and base. Apply vinegar and water solution to the well of the base and use a soft toothbrush or cotton buds to scrub off the nook and crannies of the unit.
  5. Always dry the tank and base with clean towels to wipe off any moisture left. Eliminating moisture will make your humidifier less ideal for mold spores to breed.

Use Distilled Water For Your Humidifier and Change It Daily

Will it make a difference if you use distilled water over regular tap water for your humidifier?

Some say that mold is capable of growing regardless of the type of water you use in a humidifier and that tap water is relatively clean as it goes through the public water system. 

However, according to the CDC, tap water is not sterile and still contains a small number of germs that naturally exist in the environment. If these microbes are inhaled as a mist released by a humidifier, they can cause diseases of the lungs, brain, eyes, or skin.

To be on the safer side, CDC recommends using distilled water in cleaning the humidifier parts and refilling the tank. It is essential to replace the distilled water in the humidifier every day.

Replace Humidifier Filters Routinely

Most humidifiers do have filters like home air conditioners, furnaces, and heat pumps. To keep the indoor air clean and healthy, it is vital to check if the humidifier filters need cleaning and maintenance, or even replacement. Otherwise, the dirt buildup will encourage mold to develop. 

When to change your humidifier filters depends on the kind of humidifier you own and how often you use it.

A portable humidifier used once or twice a week should have fresh filters every three months. But if you use your small room humidifier every day, replacing your filters once every six weeks is more appropriate.

A whole-house humidifier requires less frequent replacing of filters: at least once during winter if being used daily.

Read and Follow the Humidifier Instruction Manual

While most versions of humidifiers function the same, it is highly recommended to always check the unit’s manual for basic information on how to operate, clean, replace filters, and store them properly. 

Doing this will prolong the life of your humidifier and prevent mold that can compromise your family’s health.

Store Your Humidifier Properly

When spring arrives in late March or summer approaches in early July, it is time to put your humidifier to rest for the year. But don’t just toss it in the storage, or else it will be a hotbed for mold! 

Do these steps to your humidifier to avoid mold spores from developing: 

  1. Empty the humidifier tank of old water and remove the filter. 
  2. Follow the steps for cleaning listed above using distilled water and vinegar.
  3. Towel-dry thoroughly.
  4. Place it back in the box it came with upon purchase or wrap it in a plastic bag to prevent it from collecting dust and other dirt.
  5. Store in a cool dry space.
  6. Meticulously clean again before reusing it after months of storage. 

Consider A Whole-House Humidifier

Keeping your humidifier clean and mold-free may seem like a lot of work but extremely important. 

To make the cleaning and service routines less tiresome, many invest in whole-house humidifiers. Why?

Whole-house humidifiers only require annual maintenance. And because it is connected to your cooling and heating systems, you can avail of your trusted contractor services for your entire HVAC and central humidifier. It is also hard to miss your schedule to clean your humidifier as it is tied to your other systems.

Central humidifiers also make it easier for managing the level of humidity easier than having to mind multiple devices in different rooms in the house. If you keep the moisture level under control and within parameters, there is less chance for mold and its pesky friends to jeopardize your family’s well-being and your home’s structural integrity.

2 thoughts on “Do Humidifiers Cause Mold? 3 Big Problems Caused By Humidifiers”

  1. What brand do you recommend? I had an Aprilaire that was quite old and made a lot of noise so I turned it off. I do feel that my air is drier without it but it’s much quieter. I am replacing my furnace and the contractor has an option to add an Aprilaire. The new furnace will be a Lennox. Any recommendations?

    • Aprilaire is a very good brand so I think you’ll be happy with that choice. As far as noise, most newer humidifiers tend to be very quiet. The most common noise complaint is hearing water running. But that shouldn’t be any different than any other appliance that uses water. If you install a bypass humidifier instead of a power humidifier it will have less moving parts and less possibility for noise issues.


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