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Can Humidifiers Cause Mold

Can Humidifiers Cause Mold? [ 4 Reasons Revealed]

Humidifiers are a must-have for many of us, especially on cold and dry days. We resort to a humidifier for various reasons. Some use it to relieve the cough and congestion, and some use it to protect skin and hair. However some customers found mold grows in the room while using a humidifier. 

Can humidifiers cause mold? Yes. Using humidifiers can lead to higher risks of mold growth. If you don’t regulate the humidity level or don’t clean the humidifier regularly, the mold can survive and thrive on the walls or other places in your room. 

But why can a humidifier cause mold, and how to prevent it from happening? You can find the correct answers to these questions in this post!

Without further ado, let’s dive in!

What is mold?

Even though mold gives creeps to many of us, few people understand what it is. Mold is a kind of fungi that grows in hyphae. Hyphae can release mold spores which need an excessive moisture environment to survive and thrive.

There are thousands of types of molds, and not everyone is terrible for us. But many molds we find in our house can usually pose dangerous threats to our health. Some dangerous molds include Stachybotrys, Penicillium, and Aspergillus. 

Molds are not always black. Some of them are green, orange, and pink. 

The mold spores can get into our lungs through the airway, causing allergies, infections, or triggering asthma. Exposure to molds also relates to the development of asthma in children. 

That being said, for the sake of our health, we should stay away from molds.

How do molds grow at home?

How do molds grow at home

Molds exist indoors and outdoors. The mold spores outside can get into the house through doors, windows, and HVAC systems. They can also attach to clothing, bags, and other personal belongings. In addition, the old water supply pipe also contains rust and mold. 

Mold can thrive in dark, moist, and warm places. You can find many spots that meet these requirements, such as our bathroom and basement. When mold spores land in these places, they find a new residence and start to build their kingdom. 

Situations can worsen when there is a leaking pipe, flooding, and poor ventilation. When you have a humidifier running, it could be another culprit of mold growth at home. 

Why can humidifiers cause mold? 

As I said initially, humidifiers can cause mold. In this section, I will explain why humidifiers can increase the risk of mold growth. 

Humidifiers can excessively increase the humidity level

The ideal indoor humidity is usually between 30% to 55%. While humidifiers can make us feel more comfortable in dry climates, they can also lead to dampness in the air. 

When you use a humidifier in a humid room, the moisture level can quickly go over 55%, creating a suitable environment for mold to grow. 

It also happens when people don’t know how long they should run the humidifier. In some regions, the humidity varies from morning to night, meaning that you may only need to use a humidifier in the afternoon. 

If you continue to use it day and night, the indoor humidity can result in excessive moisture and mold growth accordingly.

You can use a humidifier with a built-in humidistat or monitor the humidity level through a hygrometer to stop your house from becoming the peri dish of mold growth. 

Stagnant water in the humidifier reservoir

The standing water in the humidifier tank is a haven for mold. Many people like to add tap water to a humidifier, and the mineral buildup provides sufficient for mold to eat and grow. 

As you know, many types of molds tend to grow within 12 to 24 hours. Therefore if you don’t change the water out often, the mold in the reservoir can start to thrive. 

Things can get relatively better when you use distilled water, but you still need to clean the device at least once a week. 

The mold spores in the dirty humidifier tank can be released into the air along with the water mist and then find their new residence in the furniture. They will wreak havoc on our entire respiratory system if we breathe them in.

The mineral buildup will also get into the air as white dust, extending our time on cleaning.

The humidifier is leaking 


Humidifiers can often last for years. But it can go wrong at some point in your life. If it is leaking, the water can drip on the surface, back, or front of the table or furniture where the humidifier is placed. Sometimes, the mold grows in the bottom of the device. 

You should get an electrician to fix it or purchase a new one. 

Can humidifiers cause mold on walls?

Yes. According to what we discussed above, the humidifier can increase the humidity level around the walls and disperse mold spores into the air. 

The wall is a common food source for molds. With the help of a humidifier, the mold can grow happily on it.

How Do I Know if There is Mold in My Humidifier?

The most straightforward way to identify mold in a humidifier is by checking the tank water directly. 

If the water turns black, black mold is likely growing. Of course, there are other causes. Sometimes, you can also find the pink mold and green mold in the tank. 

Another way is to smell the odor. If the water has a musty smell but the water looks normal, mold may be thriving under the table.

How to prevent mold when using a humidifier?

Don’t be afraid to use a humidifier because it may cause mold. There are three effective and easy ways to avoid it.

Clean and disinfect the device regularly 

clean humidifier reguarly

Humidifiers are notorious for cleaning and maintenance. However, you have to do it if you want it to function properly.

Use vinegar or other cleansers to thoroughly clean and disinfect the base and the reservoir every a few days and remember to change out the water every day even though some models can run up to 36 hours. 

In this way, you can remove most of the mold spores hiding in the water and tank. 

Use distilled water

If you struggle to commit to regular cleanings, using distilled water can save you some effort. Distilled water is free of minerals, which promote mold and bacteria growth. 

The device will not be as susceptible to clogs as before. You could also get rid of the white dust coming out of the tank. 

Regulate humidity level constantly 

As long as the humidity level does not go over 55%, the humidifier will not cause mold. So keeping the humidity level under control is critical when using it.

You could choose a model with a built-in humidistat so that it can shut off automatically when reaching the target level. Alternatively, you can use a hygrometer and monitor the moisture level every a few hours. 

Consider buying a vaporizer 

These days, the dividing line between humidifiers and vaporizers has become blurred. If you want to stop the mold spores in the tank from spreading to the air, using a vaporizer would be helpful since the heating elements can kill most molds and bacteria.

On top of it, many vaporizers recommend using tap water for increasing conductivity. (You may need to add salt when using it.)


Humidifiers can gradually release mist and vapor into the air, increasing the humidity level. When used properly, it can help relieve dry skin, sore throat, and dehydrated mucous membranes. However, when you fail to do it and make the room too wet, it can cause mold in your home and the water tank. 

To prevent it, you should clean and disinfect the appliance regularly. Meanwhile, use a hygrometer or humidistat to regulate the humidity level. Filling the tank with distilled water is also crucial. I am sure you can continue to enjoy the benefits of a humidifier without the disruption of molds by following this advice.

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Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested more than 150 products in person, including humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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