Can Humidifiers Cause Mold In A Room Or Carpet?

Last Updated on: 11th December 2023, 07:24 pm

A humidifier is an important household appliance that is used to make the indoor air more convenient and comfortable especially if you live in a cold or dry environment.

This handy device helps tackle many issues such as congestion, dry skin, respiratory problems, and other health conditions caused by dry air. If you want to know about how a humidifier works, you can read this post by the author.

But can a humidifier cause mold? Yes, a humidifier can cause mold if it is not properly maintained and cleaned. Mold can grow in the water tank and on other parts of the humidifier if it is not cleaned regularly.

It is important to follow the manufacturer’s instructions for cleaning and maintaining the humidifier to prevent the growth of mold. Additionally, it is important to make sure that the humidifier is not adding too much moisture to the air, as high humidity levels can also contribute to the growth of mold.

Table of Contents

can a humidifier cause mold?

But first, let’s discuss what mold is and what causes its growth in our homes.

What are Molds?

Molds are a type of fungi that is composed of hyphae. They release mold spores as part of their life cycle and can be present both outdoors and indoors where moisture and oxygen are present

. There are hundreds of species of molds consisting of various colors such as black, green, orange, or white.

Molds thrive in damp and humid conditions and can be present in your bedroom, kitchen, bathroom, or other areas that have excessive moisture. Mold Growth in a humidifier badly affects indoor air quality leading to various health problems such as:

  • Stuffy nose
  • Sneezing
  • Wheezing
  • Itchy eyes
  • Coughing
  • Headache
  • Skin rash
  • Difficulty breathing

What Causes Mold Growth in Homes

Molds in a humidifier are caused by releasing tiny spores into the air that are invisible to the naked eye. They can grow at any place where conditions are favorable for their growth. It is necessary to know those elements and factors which cause mold to develop in your indoor environment to fully eradicate this problem.

The factors that contribute to mold formation in a humidifier include:

  1. Mold spores
  2. Presence of moisture
  3. Oxygen supply
  4. Darker areas where sunlight is limited
  5. Warm and damp places
  6. Food sources ( such as organic material in walls or paints)

Some circumstances in your home make your indoor environment a perfect breeding ground for these tiny molds to thrive. These include; poor ventilation, a damp basement, home flooding, wet clothing, leaking pipes, or a leaking roof.

How Using a Humidifier Can Cause Mold Growth

A humidifier can cause mold growth in your home in many different ways. Here are the common ones:

Overusing a Humidifier Can Increase Humidity Levels

Overusing a humidifier can contribute to increased humidity levels in your home that may exceed the standard value of 55% This leads to excessive moisture and dampness creating a favorable environment for mold to grow.

According to the EPA, indoor humidity levels should be between 30 and 50%. Sometimes, the recommended levels of humidity may also exceed if the in-built hygrometer of a humidifier gives false or inaccurate readings.

Read this post if you’re wondering how long it takes for a humidifier to work.

Lack of Proper Cleaning And Maintenance

can a humidifier cause mold?

The stagnant water in the humidifier provides ideal conditions for mold to grow and spread. Many owners use tap water in their humidifier that contains minerals. The mineral buildup in the water reservoir thus serves as a food source for these molds causing them to grow exponentially within a short time.

If this water is not replaced and refilled in time then mold can be carried away with the water mist and spread into your indoor atmosphere and surfaces such as walls and window sills. Likewise, if the humidifier is not cleaned properly and regularly, it can breed harmful mold and bacteria.

Leaking Humidifier

If you notice water on the surface, front, or back of a table or counter where you have placed your humidifier, it means your humidifier is leaking. The leaking humidifier may cause mold to grow. You’ll have to call in an electrician to help fix your leaking humidifier.

Using a Humidifier When Not Needed

Using your humidifier, especially during the summer when the weather is warm and humid may contribute to excessive humidity levels that can promote mold growth in the environment.

Moreover, areas in your home such as the kitchen or bathroom already have increased humidity. Using a humidifier in these rooms will add extra moisture causing mold and dust mites to thrive.

Mineral Build up in a Humidifier

If you use tap water instead of distilled water in your humidifier, it may contribute to mineral accumulation. This mineral buildup contains calcium, magnesium, and sodium which serve as a food source for these bacteria and mold to grow and flourish. These microbes are released through water vapor contaminating your indoor air.

How to Identify If there is Mold in the Humidifier?

You can know if there is mold in your humidifier by doing a visual inspection of your unit. Look inside the water chamber or other parts that are in contact with water for any signs of mold. Mold growth can appear as black, pink mold, or green spots.

The second method to identify mold in your humidifier is to take a smell test. If you notice musty odors coming out of your device, chances are your humidifier is contaminated with mold growth.

Moreover, if you observe that your allergy and other respiratory symptoms are aggravated after using your humidifier, know that there is mold in your indoor air that is released through the mist from your device.

Important Tips to Prevent Mold Growth

can a humidifier cause mold?

Fortunately, there are some ways that you can follow to prevent mold growth when using a humidifier. These include:

Use Distilled Water

Using the right type of water is essential to avoid mold formation. Unfiltered tap water contains minerals such as calcium and magnesium which lead to mineral buildup or scale formation. This encourages the growth of mold and other microbes that are distributed in your room’s air through water vapors.

Therefore, it is recommended to use distilled or demineralized water that has a lower mineral content to avoid the formation of mold. You can easily find distilled water at supermarkets or grocery stores.

Monitor the Indoor Humidity Levels

Mold formation occurs when the relative humidity levels go above 55%. Therefore, you should keep an eye on your indoor moisture levels. The ideal humidity level for your home should be between 30 and 50%. You can use a built-in humidistat or purchase a digital hygrometer to keep track of moisture levels in your room.

Keep the Area Surrounding the Humidifier Dry

Excessive moisture can make the surfaces around your humidifier wet and damp which favors mold formation. You can decrease your humidifier’s mist output setting if you notice wet surfaces around your unit or on your walls and furniture. Also, use your humidifier intermittently or only when needed.

Place your humidifier at the right location to prevent your furniture and carpet from getting damp. You can also place a towel or mat under your device to protect the furniture.

Regular Maintenance and Cleaning of the Humidifier

Dirty humidifiers cause potential health risks for people with allergies and asthma when the contaminated mist is released into the atmosphere. Therefore, proper maintenance and cleaning of your device are important to ensure healthy indoor air.

Always unplug your device before you clean it. Disassemble the device and thoroughly wash and clean your humidifier’s filter, water tanks, and other parts. Make sure your humidifier is completely dried before you reassemble it. It is suggested to clean your device at least once a week.

Before starting any cleaning or maintenance procedures, always follow the manufacturer’s instructions and recommendations. Regular maintenance of your device prevents mold accumulation and ensures the optimal functioning of your humidifier.

Disinfect the Humidifier

You can remove scale and mineral buildup using a vinegar solution. Add one cup of vinegar in equal amounts of water and use this solution with a brush to remove mineral deposits.

Hydrogen peroxide acts as an excellent cleaning agent to disinfect your humidifier. For this, make a 3% solution of hydrogen peroxide and allow this solution to remain in the tank for about half an hour. Next, rinse thoroughly with fresh water and let your device dry completely before you use it again.


Humidifiers may increase relative humidity beyond the recommended values if not used properly. Excessive moisture can promote mold formation which is harmful to our health. Also, poor maintenance and negligence may result in mold growth in the humidifier and subsequently in the indoor environment.

However, if you clean and maintain your humidifier regularly, use the right type of water in it, and monitor the indoor humidity levels constantly then you can significantly prevent mold formation and improve the indoor air quality of your home.