Brown Stuff In My Humidifier: What Is It & How To Remove It

Humidifiers have become a common household appliance in American homes. It is a godsend for people who live in arid regions.

A humidifier increases indoor humidity by expelling water mist or vapor. Hence, the water tank and base are crucial parts as they hold the water that will be evaporated.

Over time, you may find brown stuff present in your humidifier and don’t know what it is. 

Don’t be agitated! Brown sediment in humidifiers often comprises mineral buildup, mold, dirt, and dust. It is a common thing to see and you can handle it easily.

If you want to know how this ugly brown stuff is formed in your humidifier and how to get rid of it, look no further! You have come to the right place as I will cover all the information you need to know in this post.

What is the brown stuff in my humidifier?

Not every humidifier will have brown stuff in it. It will appear when something gets into the humidifier. 

Mineral buildup is the main culprit. When you put tap water, well water, or other water containing dissolved minerals into your humidifier, the calcium, magnesium, iron, and other minerals will settle down and become buildups in the tank.

brown mineral buildups

In the beginning, these deposits have a white color, which is the slime and scale we often have seen. However, if left for a long time, it will turn brown.

Mold is another primary cause of brown stuff. You may have never noticed, but mold spores are everywhere in the air. They always hunt for new residences that are warm and damp, and the water tank of a humidifier is the perfect place to go. 

brown mold

Within 24 to 48 hours, mold spores will start to thrive in the humidifier, and then you will be able to see them. Molds come in different colors, like black, brown, pink, and green. That’s why some customers also see pink mold and black stuff in their humidifiers. 

Meanwhile, dirt and dust can also get into the humidifier through the mist spout. When they accumulate, you will see the sediment with brown color too. 

Frankly, the brown stuff in a humidifier is often a mixture of mineral deposits, mold, dirt, and dust. It doesn’t consist of a single type of substance.

How to identify brown stuff in your humidifier?

Even though it is likely a mixture of mold, mineral buildups, and dirt, you can tell the composition by touching it.

Mineral buildups are hard, dry, and difficult to remove, whereas molds can be wet and slimy. By knowing the main components of the brown stuff, you can decide which cleaning method to use. 

Health risks you should know

Keeping the humidifier is essential for every user. When you see brown stuff in the tank or base, getting rid of it as soon as possible is needed.

If you use an ultrasonic humidifier, the mineral particles will get into the air as “white dust” along with water mist. White dust can cause complications in the lungs when inhaled. When it settles out on the furniture, it will prolong your time on cleaning. 

However, mold can pose more health risks to you than mineral deposits. When mold spores are expelled into the air, they will get into your body when you breathe, causing breathing difficulties, headaches, allergic reactions, or even asthma flare-ups. They also contribute to lung infections

As the main components of brown stuff are mineral buildups and mold, you should clean it off to prevent these health threats.

Other than that, brown sediment can clog the machine, shortening your device’s lifespan

How to remove brown stuff in the humidifier?

Once you understand how to get rid of mineral sediment and mold, the brown stuff will disappear in your humidifier. Note that you should follow it if the manufacturer has provided the instruction.

Mineral deposits are difficult to remove through scouring. You need to use some acid solution to dissolve it. Rather than buying a specific cleanser, white vinegar in your kitchen can get the job done well

Pour one or two cups of undiluted white vinegar into the tank and let it sit for one hour or more, depending on how much brown stuff it has. Then use a soft cloth or bottle brush to give the water tank and base a good scour. 

Molds can be easier to remove. Sometimes, you can use a soft damp cloth to wipe it away. However, the tiny mold spores and bacteria are invisible to you. You should take measures to sanitize these microorganisms. 

You can choose white vinegar, 3% hydrogen peroxide, bleach, or alcohol to kill the molds and bacteria. The method may vary according to what you use.

How to prevent brown stuff from showing up again?

To avoid brown stuff in your humidifier, you should commit to two things. 

Firstly, clean your humidifier regularly. Every day, dump the stagnant water in the water tank and base and then refill it with clean water. Every week, give your humidifier a thorough clean. Disinfection is also needed.

Secondly, rather than tap water, running your humidifier with distilled water is much better. Distilled water is free of minerals, which can largely reduce the formation of brown sediment.


Humidifiers can dirty over time. If you don’t maintain it well, brown stuff can manifest inside. 

The brown stuff in your humidifier is likely caused by mold, mineral deposits, dirt, and dust. More often than not, it is a mixture of these substances. 

Please don’t neglect the effect of this unpleasant stuff. It can result in respiratory infections, allergies, and other conditions. It will also lead to the malfunction of your device. 

The brown stuff is also a clue that cleaning is overdue. Cleaning and disinfecting your appliance more frequently and filling the tank with distilled water will help you get rid of it for good. 

About The Author

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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 dozens of products in person, like 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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