Why Does My Humidifier Smell?

This article discusses possible reasons for smells coming from a humidifier. 

The smell coming from a humidifier could point to several problems inside the unit. Some of these problems could even cause health issues for you and your family. 

Your humidifier might smell because of mold, water deposits, bacteria buildup in the tank, or all three! 

It’s recommended you address these problems early on to ensure the continued high performance of your unit. 

Here, we tell you how to identify the cause of different smells coming from your humidifier and what you can do to deal with them. 

Keep reading to learn more about why your humidifier smells. 

Why Your Humidifier Smells

There are a few possible reasons your humidifier smells. It is important to identify what is causing the smell so that you can take care of the problem early on. 

If neglected, whatever is causing the smell could spread and lead to health problems. 


One of the most common reasons for smell coming from a humidifier is the buildup of bacteria or other microorganisms. If your humidifier doesn’t get cleaned regularly, bacteria can thrive in the water tank, the wick, or even the filter. 

As the bacteria spread and grow, they release the smell you might be experiencing. These bacteria can cause diseases, so taking care of the problem as soon as possible is important. 


Another common cause of smell coming from a humidifier is mold. Mold is caused by fungi that deposit in the humidifier and spread from there. And since mold thrives in damp and humid conditions, it makes sense that humidifiers are especially susceptible. 

Mold is extremely dangerous and can cause various health problems, such as coughing, allergic reactions, breathlessness, skin irritation, rashes, watery eyes, and many more. 

It’s easy for mold to spread from your humidifier to your surroundings. Mold can be released into the air and settle on people, pets, food, furniture, and walls. 

Here, it causes many health issues and even ruins wood furniture, paint, and fixtures around the house. Again, you must address the problem quickly. 

Water Deposits

Deposits from the water you use for your humidifier can also cause it to smell. This is especially true if you use hard water, i.e., water that has very high mineral content. 

Mineral deposits can build up in the water tank over time and give off a strong, musty smell. 

So now that we know what might be causing the smell in your humidifier, let’s discuss how to get rid of it. 

How To Get Rid Of The Smell In A Humidifier

If you experience a smell coming from your humidifier, one of the reasons mentioned above is probably the culprit. The good news is that no matter the cause, almost any odor coming from your humidifier can be dealt with by cleaning it thoroughly. 

So if you notice a smell coming from your humidifier, break out the cleaning supplies and clean the water tank, the nozzle, and maybe even replace the filter for good measure. 

And if you aren’t sure how to clean your humidifier, here’s our step-by-step guide. 

Step 1

Unplug the humidifier from the wall. 

Humidifiers should never be cleaned while plugged into the wall. 

Step 2

Open up the water tank and pour out all the water. 

Make sure you dispose of this water responsibly. It could contain mold, which can easily spread and cause various health problems. 

Step 3

Thoroughly rinse the entire tank with distilled water. 

We highly recommend using distilled water to clean the humidifier. This is because distilled water is completely free of minerals, heavy metals, and other contaminants that might be causing the smell in the first place. 

Step 4 

Use dish soap and a sponge to go over the entire surface of the tank. 

This should kill most of the bacteria and take care of any deposits in the water tank. 

That should take care of most any smell coming from your humidifier. The only exception is if the humidifier gives off a smell because it has developed mold. In that case, you will need to do a few things differently. 

If you suspect the smell from your humidifier is caused by mold, follow this guide to clean it. 

Step 1 

Prepare a cleaning solution made by mixing 3% hydrogen peroxide and distilled water. Add 3 parts distilled water to 1 part 3% hydrogen peroxide. Alternatively, you can use distilled white vinegar and water in equal parts. 

Step 2

Fill your humidifier’s water tank with the cleaning solution. If you notice any mineral deposits or mold anywhere inside the tank, make sure the cleaning solution covers them. 

Step 3

Close the water tank and shake it vigorously. Shaking the tank ensures that the entire inside surface of the tank is covered by the cleaning solution. 

The shaking motion also dislodges larger deposits, making it easier to clean the tank. 

Step 4

Next, let the tank sit for a while with the cleaning solution still inside. We recommend waiting at least an hour for the cleaning solution to work its magic, but you might need to wait even longer if the level of contamination is higher. 

Step 5 

Open the humidifier’s water tank and pour out the cleaning solution. This should have removed all the mold causing your humidifier to smell. 

If you still notice some mold stuck inside the tank, you should repeat the whole cleaning process but use a stiff bristle brush to remove the mold. 

Step 6 

This is an extra step, but it doesn’t hurt. 

Once you’re done cleaning the mold out of your humidifier’s water tank, we recommend regular cleaning with the dish soap and sponge. This isn’t necessary, but we find that the cleaning solutions can leave a smell. 

By cleaning the tank again, you can remove all the smells from your humidifier. 

How To Prevent Your Humidifier From Smelling

So if the smell coming from your humidifier is caused by mold, bacteria, and water deposits, what can you do to prevent these things from happening?

Clean The Humidifier Regularly

It’s easy to prevent your humidifier from smelling. All you need to do is keep up with the regular cleaning and maintenance of the unit. 

Regular cleaning and maintenance prevent minerals from becoming deposited in the water tank. The soap or cleaning solution you use also effectively kills bacteria, fungi, and other microorganisms that might have found their way into the tank. 

Regular cleaning is also essential to avoid mold in the water tank. We recommend cleaning your humidifier at least once a week. 

If the humidifier gets used often or at very high mist settings, even more frequent cleaning might be required but once a week is the minimum. 

It might also be a good idea to follow up every other tank cleaning with a descale. You can use the same cleaning solutions used to clean out mold from the tank to descale the tank. 

Replace The Filter Regularly

In addition to regular cleaning, you also need to replace the filter regularly. The filter in a humidifier filters out a lot of contaminants, microbes, and minerals. This makes it a hotspot for mold, bacteria growth, and mineral deposits. 

We recommend replacing the filter at least once every couple of months. Again, if the unit gets used often or uses very high mist volume settings, you might have to replace the filter more often. 

It is best to contact the manufacturer of your particular model or consult the manual to see how often you need to replace the filter. 

Change Out The Water Between Uses

This is important for humidifier units that don’t get used as often. 

If you leave water in the tank between uses, it can very quickly become stagnant. Stagnant water is a breeding ground for all kinds of bacteria and other microorganisms that give off the smell you might be experiencing. 

These bacteria also carry various diseases, so replacing the water in your humidifier is essential. 

Additionally, you should always empty the water tank before storing your humidifier. Bacteria and mold thrive in dark, humid places, so staying one step ahead is important. 

Use Distilled Water In Your Humidifier

Distilled water is water made by a process called ‘distillation.’ Unlike purified water, which is free of all contaminants but retains some minerals, distilled water is free of all contaminants, minerals, and heavy metals. 

You can significantly reduce the risk of a humidifier developing mold or mineral deposits if you use distilled water. That doesn’t mean you can go without cleaning the humidifier completely. But it does lower the chances of mold, which is a plus.


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.