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What is the Brown Stuff in My Humidifier?

What is the Brown Stuff in My Humidifier?

Humidifiers are great for relieving the symptoms of dry air and damage caused by central heating. However, mineral deposits can build up in a humidifier over time due to calcium and other minerals in the water. 

As the water evaporates, minerals form in the tank, filter basket, water tray, and other components within the humidifier, depending on the model. The brown stuff can also be due to dirt and mold accumulating in the unit, emitting brown particles into the air.  

Here is what you should know about the brown stuff in your humidifier and how to clean it:

Why Is the Water In My Humidifier So Dirty?

The water in your humidifier could be dirty and brown due to dirt, mold, or minerals. There’s a mineral buildup in your humidifier because when you drain water from your humidifier, the minerals that are present in the water often stick to the insides of your device. 

Over time, the mineral deposits form a layer of brown sediment that needs to be removed to prevent mineral particles from being emitted by your humidifier once you turn it on. 

Dirt that enters from outside, mold that grows in the moisture, and the minerals buildup form a progressively thick layer of sediment on the inside of your humidifier, which leaches into the water and into the air emitted by your humidifier. 

What Color Is Mold In a Humidifier?

Fungi and bacteria grow very fast in warm and moist conditions, such as those in a humidifier. These organisms multiply extremely fast when left alone, form a furry brown layer inside your humidifier, and allow mold particles to be emitted in the air. 

Having mold in the humidifier is an extremely common problem that you should take care of before it gets out of hand. 

How Does Dirt Get Into Your Humidifier?

Humidifiers are not sealed; dirt and dust can enter while it’s stored and running. This issue is also a risk for devices that are stored near windows. 

If you also get your water from a well and are less diligent about replacing filters, dirt can come from the water you put in the humidifier. 

How Do You Identify the Brown Stuff In Your Humidifier?

Mold is irregularly-shaped specs of black, white, green, yellow, orange, or brown or looks like a fury growth. It’s also soft enough to start coming off when you scrub it; however, that’s not the best way to clean it. 

On the other hand, the sediment caused by mineral buildup can become so hard that scrubbing might seem to make no difference. When the humidifier is dry, mineral buildup also feels dry to the touch, while some molds are slimy. 

However, it doesn’t matter which of the two materials is the problem because you will need to use methods to clean both mineral buildup and mold from your humidifier if you haven’t cleaned it in a while. 

Is the Brown Residue in My Humidifier Unhealthy?

The brown residue in your humidifier is unhealthy and can lead to several health complications if left unattended. Researchers have linked several health conditions to the occurrence of molds, minerals, and dirt in the air. 

Common illnesses linked to a dirty humidifier include asthma, a persistent cough, pulmonary fibrosis, and diminished lung function. Additionally, it’s best to take note of the following:

  • Mold can cause persistent cough and wheeze, especially in infants and children.
  • Some molds, such as Penicillium, can lead to hypersensitivity pneumonitis, a type of allergy that might result in shortness of breath, weight loss, or exhaustion. 
  • Moldy humidifiers can result in an influenza-like illness called humidifier fever, which has symptoms like headache and fatigue. 
  • When tiny mineral particles and chemicals settle in the lungs, they might cause diminished lung function, asthma, or inflammation. 

How to Remove the Brown Stuff in my Humidifier

It’s most likely that your humidifier manufacturer has specific guidelines you should follow when cleaning. You can follow this guideline if you don’t have the cleaning instructions from your manufacturer:

How to Clean Mold From Your Humidifier

You can clean mold from your humidifier by following these simple steps:

What You Need

  • Hydrogen peroxide 
  • Bleach (optional)
  • Water
  • Soft bristle brush


  • Put hydrogen peroxide on a wet, soft bristle brush and scrub the inside of the tank and tray. Hydrogen peroxide is a safe disinfectant designed for wound care; therefore, it’s safe to inhale.
  • You can opt for bleach if the above procedure doesn’t remove the entire mold. Add a tablespoon of unscented chlorine liquid bleach to a gallon of water and let it stand in the tank 
  • for at least twenty minutes before you continue scrubbing.
  • Rinse the tank thoroughly and dry it before the next use. If you require more bleach than a tablespoon, it’s best to vacate the room or house the first time you run your humidifier.
  • If your humidifier is portable, the best option is to take it outside, put the bleach solution in the tank, and run it for at least thirty minutes to ensure that nobody is in danger of inhaling strong chemicals. 

It’s best to remember that evaporative humidifiers are likely to have an antimicrobial coating on the filter, which disinfectants can easily destroy. Therefore, don’t expose it to one of those; just replace the whole filter if mold is growing on it. 

Wearing an N-95 mask while scrubbing will also prevent you from breathing mold spores during cleaning. 

How to Clean Mineral Deposits From a Humidifier

Certain acids can effectively dissolve calcium and other mineral deposits in your humidifier. Here is how you can clean mineral deposits from a humidifier:

What You Need:

  • White vinegar
  • Clean cloth
  • Cotton swabs
  • Baking soda


  • Turn the humidifier off and unplug it from the wall socket.
  • Remove the water tank from the humidifier base and the motor housing if your humidifier has one from the base. If your device has a separate water tray or filter basket, remove it.
  • Remove the filter from either the water tray or the filter basket and set it aside.
  • Fill the humidifier base or separate water tray with undiluted vinegar. 
  • If your humidifier has a filter basket, place it in a sink and fill it with undiluted vinegar. 
  • Open the cap on the water tank and fill the tank with undiluted vinegar.
  • Let the vinegar remain in these parts for 20 to 30 minutes. 
  • Clean the inside of the parts with a clean cloth and vinegar that’s already in the components. Next, use a cotton swab to remove any scale you can’t reach with a cloth.
  • Rinse the vinegar from each of the humidifier parts with clean, warm, running water, and dry the components thoroughly.
  • If white vinegar seems ineffective, your humidifier might be contaminated with acidic minerals, which can be removed by a solution of baking soda and water. 
  • Stir four tablespoons of baking soda into a quart of warm water, dip a scrubber or brush, and scrub the tank and tray to remove the stubborn mineral deposits. 

It’s best to clean your humidifier once a week with vinegar to ensure that it’s operating at optimal efficiency. It’s also best to avoid washing the filter with vinegar because it will damage it. 

How to Prevent Your Humidifier from Getting Dirty Again

Having gunk in your humidifier is very unpleasant. However, you can prevent your humidifier from getting dirty by adopting a regular cleaning routine during the season when you use it the most. 

You can do the following simple tasks to ensure that your humidifier is clean and fresh:

  • Empty the tank, dry all the surfaces thoroughly, and refill it with clean water every one or two days.
  • Empty the water on days when you don’t use the humidifier and allow the filter and tank to dry. 
  • Use distilled water rather than tap water in your humidifier because it doesn’t contain fungi, bacteria, or minerals to clog up your humidifier. You can also use water that has gone through your reverse osmosis system. 
  • Ensure the device is clean and dry before storing it at the end of the season. It’s also best to clean it again at the beginning of the new season before use. 
  • If you have an evaporative humidifier, replace the filter according to the manufacturer’s recommendations. 

Humidifiers are great for preventing dry cough and skin caused by dry air; however, you must follow a diligent cleaning routine to ensure that you don’t have brown stuff in your humidifier water that can lead to several health complications.