Can A Humidifier Cause Mold?


Yes, a humidifier can cause mold growth if not properly cleaned and maintained. Mold thrives in moist environments and can grow on the surfaces inside a humidifier that have accumulated mineral deposits and organic matter. To prevent mold growth, it’s important to regularly clean the humidifier and replace the water with fresh, clean water.

What is the main cause of mold? The answer is easy. Mold is caused from damp, humid conditions. The use of a humidifier for breathing assistance and to moisten the air is common in dryer climates. Many use these devices at various seasons to improve their indoor air quality, but due to the damp environment within the machine, humidifiers have been known to cause mold to develop in homes. A humidifier can cause mold in a variety of different ways.


Humidifier owners can often overuse their device causing the potential for mold to form in their home. The EPA and other environmental regulatory firms indicate that relative humidity for any home should remain between 30% and 50%. A humidifier is designed to increase humidity inside your home, but moving beyond that 50% mark can lead to the potential for mold to develop.

Overly humidified air is unhealthy and many homeowners will make the mistake of leaving their humidifier running on high for too long. Once the RH inside your home reaches 70%, the potential for mold spores to grow is drastically increased.

Poor Maintenance

Regular maintenance on your humidifier is essential for maintaining a mold free device. Mold develops and thrives quickly in a damp environment and keeping your humidifier full of stagnant water is the fastest way to potentially cause mold and spread it around your home.

Clean your humidifier regularly and wipe down components of the device while cleaning. Disinfectants used on the humidifier can help you keep mold from developing and spreading through your home. A cleaned humidifier can make your home much healthier and happier.

Mineral Buildup

Mineral buildup in your humidifier can happen. When you look at your reservoir and see residue along the edges, this is called scale. Scale is minerals that have built up from the water in the tank. Regular cleaning can help minimize scale that feeds mold, so minimizing scale buildup goes hand in hand with regular maintenance.

What Can You Put In a Humidifier to Prevent Mold?

Although there are a lot of various hacks and expert tips for what to put in your humidifier, most of these are not to be trusted. A high end humidifier is something you need to take care of and the best way to do that is to regularly clean the machine and use only distilled water.

Distilled water contains far less chemicals and minerals than standard tap water. Even the use of a filter may not be enough to remove all, potentially harmful minerals. Using distilled water not only makes clean up easier, as you will not be contending with excess mineral buildup, it can also make the humidifier and the filter last longer.

There are several things you can put in a humidifier to prevent mold growth:

  1. White vinegar: Adding a cup of white vinegar to the water in the humidifier can help to kill mold and bacteria.
  2. Hydrogen peroxide: Mixing a few drops of hydrogen peroxide with water in the humidifier can also help prevent mold growth.
  3. Essential oils: Some essential oils, such as tea tree oil and eucalyptus oil, have natural antifungal properties that can help to prevent mold growth.

It’s important to regularly clean the humidifier and replace the water to maintain its cleanliness and prevent mold growth. Additionally, it’s recommended to follow the manufacturer’s guidelines for proper usage and maintenance of the humidifier.

What Happens if You Breathe In Mold from Humidifier?

Mold spores in the air can be dangerous to those with a compromised immune system or existing breathing problems. Although it is unhealthy for anyone to breathe in mold spores, it is particularly damaging to sensitive individuals. Breathing in mold spores brought into the air by a humidifier can cause mild to severe breathing issues. The spores entering your body can begin to grow due to the high moisture level in your body.

Your body looks at mold spores as an invasive species and it will do whatever it deems necessary to rid the body of them. Sneezing, congestion, and other allergic reactions can occur. If you suspect mold in your home, cleaning it out is the only solution, so keep your humidifier as clean as possible and in proper working order.

How Do I Know If My Humidifier is Dirty or Contains Mold?

It can be difficult to know for certain if your humidifier is dirty, but a good indication is if you notice discoloured streaks on the tank. Blue or pink streaks are an indication that mold is present. The ideal thing to do is to maintain a regular cleaning schedule for your humidifier. Set one day each week to clean out the device. Cleaning regularly is the only way to ensure your humidifier is helping, rather than potentially hurting those in your home.

Humidifiers are great devices and should be used in dry climate homes. Overly dry air can cause skin irritation, coughing, and a myriad of other health issues. A humidifier does have the potential to cause mold, but the issue is easily resolved with careful maintenance and cleaning of the device. If you are in the market for a humidifier, ensure it is one that can be easily cleaned. Check how easy it is to remove and clean the tank before deciding on a model. With careful cleaning and using the device to maintain between 30% and 50% humidity, you should not have any mold concerns stemming from your humidifier.


In conclusion, a humidifier can contribute to mold growth in a house if not properly cleaned and maintained. Humidifiers increase the humidity levels in the air, creating a moist environment that is ideal for mold growth. To prevent mold growth in the house, it is important to regularly clean the humidifier, use clean water, and follow the manufacturer’s guidelines for proper usage and maintenance. Additionally, it is crucial to monitor indoor humidity levels and keep them within the recommended range to prevent mold growth in the house. Regular cleaning and proper maintenance of the humidifier can help ensure that it operates effectively and does not contribute to mold growth in the home.

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