Brown Stuff in Humidifier | A Guide

This is our guide for identifying, cleaning, and preventing brown stuff in a humidifier. 

Brown stuff in a humidifier might just be sediment deposits that can easily be cleaned. However, it is possible that the brown stuff in your humidifier is something much more concerning like mold or mineral deposits. 

In that case, you could experience a number of issues with the unit’s performance and even risk significantly lowering its longevity. 

Additionally, if the brown stuff in your humidifier is mold or mineral deposits, it can very easily be released into your home, which can cause various health concerns. 

We’ve been met with all kinds of brown stuff in a humidifier. So if you need help identifying what the brown stuff in your unit is and how to deal with it, leave it to us. 

Keep reading for more information about brown stuff in a humidifier. 

Identifying The Brown Stuff In Your Humidifier 

There are a couple different reasons you might be noticing brown stuff in your humidifier. 

Some common causes for brown stuff in a humidifier include dirty water, water that is rich in minerals (hard water), or even a filter that needs to be replaced. 

So what exactly is the brown stuff in your humidifier, and what caused it? 


One of the most common reasons for brown stuff in a humidifier is sediment from the water getting deposited in the tank. This is probably the case if the water being used in your humidifier is dirty. 

You can inadvertently cause sediment to be deposited in the water tank by using tap water. Tap water might get contaminated with dirt and other such particles if the pipes in your home are damaged or old. 

If the brown stuff is coarse and releases particles into the surrounding water, it is probably a sediment deposit. 

Mineral Deposits

Another possible reason for brown stuff in your humidifier is mineral deposits. This is usually the case with humidifiers that use hard water. 

Hard water is water that is very rich in minerals, making it harder for your humidifier to filter it. In some regions, tap water may also be very rich in minerals. 

When the excess minerals aren’t being filtered properly, they start to build up in the water tank and large deposits can show up as brown stuff in your humidifier. 

Mineral deposits will usually show up as hard, rough patches or stains in your humidifier’s water tank. 


Mold is a fungal growth that thrives in damp, dark places. That means your humidifier’s water tank is the perfect place for mold growth and development. 

Mold is made up of strands of fungus. It resembles fur, but if you notice brown stuff that you suspect is mold in your humidifier, you should never touch it, as it can cause various health problems. 

The exact color of the mold in your humidifier can range from dark to light brown. In fact, mold can be found in many different colors, including shades of yellow, green, red, white, gray, or black. 

Why Brown Stuff In A Humidifier Is Bad

No matter what kind of brown stuff you notice in your humidifier, it is a problem that needs to be dealt with immediately. 

If you don’t address the brown stuff promptly, there are a number of possible problems that could arise. 

Poor Humidification

Brown stuff in a humidifier, be it sediment, or mineral deposits, or mold, can cause your humidifier’s performance to suffer. 

This happens because the brown stuff may be releasing particles into the water tank which can gunk up various parts of the humidifier, such as the filter, the nozzle, or the diffuser. 

Such obstructions can cause the sensitive internal components to malfunction or not work properly, which can lead to reduced humidification capability, lower coverage, and sub-par mist production. 

Reduced Humidifier Lifespan

If the brown stuff is causing the problems we described above, it has a noticeable effect on the lifespan of your humidifier. It is possible that the humidifier loses effectiveness earlier than expected, or becomes completely useless over time. 

Your high performance humidifier unit probably cost you a fair bit of money. So if you want to protect your investment and get the most out of your humidifier, get rid of the brown stuff as early as possible. 

Health Concerns

This is probably the biggest concern with brown stuff in a humidifier. No matter what the brown stuff in your humidifier is, there are a number of health concerns associated with it. 

If the brown stuff is sediment, it can release particles into the air along with the mist. These can cause irritation of the nasal passageways, allergic reactions, and even some respiratory problems. 

Mineral deposits can also release particles into the air, where they can cause similar irritation. In fact, mineral deposits can even promote the development of mold in your surroundings. 

That brings us to the worst offender of all: mold. 

Mold poses countless health and safety risks for you and your family. If the brown stuff in your humidifier is indeed mold, it can release spores into the air, which can very easily spread to various parts of your home. 

Mold can cause a plethora of illnesses. Symptoms of mold infection include allergic reactions, coughing, sore throat, breathlessness,lung irritation, watery eyes, headaches, nasal infections, skin rashes, and respiratory issues, to name just a few. 

How To Clean Brown Stuff Out Of A Humidifier

So brown stuff in a humidifier is bad. Noted. But how do you clean it out of your humidifier and prevent it from causing more problems?

Well, the first step is to identify what kind of brown stuff is plaguing your humidifier. If it’s just sediment, something as simple as thoroughly cleaning the humidifier with soap and water might do the trick. 

However, if the brown stuff in your humidifier is mineral deposits or mold, you’ll have to put a bit more work in. 

Follow our step-by-step guide to figure out how to remove mineral deposits or mold from your humidifier. In fact, even if the brown stuff is sediment,  it’s a good idea to follow this process for good measure. 

Step 1: Prepare A Cleaning Solution

Mineral deposits and mold can’t be cleaned effectively with just soap and water. You will need to prepare a special cleaning solution. 

We recommend preparing a solution by mixing 4 parts distilled water with 1 part 3% hydrogen peroxide. Alternatively, you can also use a mixture of distilled water and distilled white vinegar in equal parts. Just be sure to use distilled water (more on that later). 

Step 2: Fill The Tank

Now that you’ve got your cleaning solution ready, it’s time to pour it into the humidifier’s water tank. Make sure you fill the tank such that all of the brown stuff is fully submerged. 

Step 3: Shake Vigorously

Next, close the water tank with the cleaning solution inside, and shake it vigorously. This ensures complete coverage of all affected areas, and also helps loosen up the more stubborn brown stuff. 

Step 4: Let It Sit For A While

After you’ve shaken the tank well, set it aside with the cleaning solution still inside. Doing so gives the solution ample time to work its magic and clean all the brown stuff out of your humidifier. 

We recommend letting the cleaning solution sit for at least an hour. However, depending on how severe the contamination is, you might have to let it sit for longer. 

Step 5: Pour Out The Cleaning Solution

Finally, pour the cleaning solution out of the humidifier, and inspect the inside to see if all the brown stuff has been cleaned away. 

If you still notice some brown stuff inside the tank, repeat the whole cleaning process, and use a thick bristle brush to agitate the brown stuff. 

How To Prevent Brown Stuff In A Humidifier

Brown stuff in a humidifier can be quite serious, and removing it is no easy task either. So what can you do to prevent brown stuff from developing in your humidifier in the first place?

Use Distilled Water

Well, as we’ve discussed, most brown stuff in a humidifier comes from contaminants in the water. That means you need to use water that is free of all contaminants that could cause brown stuff to develop in the humidifier. 

Distilled water is the best choice, as it is free of all contaminants, as well as minerals and heavy metals which can deposit in the water tank. That’s also why we recommend using distilled water to clean the brown stuff out of the humidifier. 

Purified water is also safe for use in a humidifier, but the presence of minerals means a humidifier that uses it is slightly more susceptible to the development of brown stuff. 

Hard water, tap water, and even bottled water should be avoided if you want to prevent brown stuff in your humidifier. 

Clean The Humidifier Regularly

Regularly cleaning your humidifier ensures that any contaminants or minerals that would otherwise be deposited in it are cleared away before they have a chance to become a bigger problem. 

We recommend cleaning your humidifier at least once a week, though more frequent cleaning may be required for units that get used more or at higher mist volume. 

Additionally, you should also descale the humidifier at least once a month. The process for descaling a humidifier is the same as the one used for cleaning brown stuff out of it. 

Replace The Filter Regularly

The filter in a humidifier often gets neglected for months and months at a time. The filter is exposed to all kinds of contaminants, foreign substances, and microorganisms. 

In fact, the filter is the second most prone to developing brown stuff after the water tank. That is why it needs to be inspected and replaced regularly. 

In our experience, the filter in a humidifier should be replaced once every few months. Ultimately, how often you replace the filter will depend on what the manufacturer of your humidifier recommends.


Shawn Willis is all about humidifiers. After working for some of the biggest names in the industry, he started HumidifierGuys with Scott Dawson. Now, the dynamic duo helps others figure out what they need in their next humidifier.

Shawn is an avid sports fan, motorcycle enthusiast, and has two dogs named Whiskey and Boba.