Humidifiers: 4 Best Things To Add To A Humidifier Reservoir Against Mold


4 Best Things To Add To A Humidifier Reservoir For Mold header image

A humidifier is a great tool to run when the air is dry in order to reduce congestion and some skin conditions. But what if your humidifier is making your eyes burn and make you even more congested? There is a good chance there is mold growing in your humidifier and it has to be cleaned out. How can you do this? Here’s what you want to know. 

Mold in a humidifier can be fixed by adding things like; vinegar, hydrogen peroxide or lemon juice to the reservoir and running the humidifier. These liquids will kill the mold although cleaning the filter and reservoir by hand might still be necessary to get rid of all the growths. 

Let’s get into the details of these additives and how you can use them. 

4 Best Things To Add To A Humidifier Reservoir Against Mold

Here are the four best things you can add to a humidifier to prevent mold growth. To be clear, these are to prevent mold growth in the humidifier, not the space you’re using the humidifier in.

1. (Apple Cider) Vinegar

Apple cider vinegar

The best thing to add to a humidifier is some vinegar. You can use simple white vinegar but apple cider vinegar because most people prefer the smell. It might not be the absolute most effective but it is cheap and readily available in pretty much every kitchen. A cup of vinegar in the reservoir will help prevent the growth of mold. Of course the machine has to be run for the vinegar to do it’s job properly. 

While you wouldn’t necessarily do this for the smell, it can help neutralize bad smells in the space you’re humidifying. The main reason to do this is to keep you humidifier in good condition. The vinegar will neutralize all the bacteria and mold that potentially live in a humidifier. 

Using vinegar once in a while will get rid of potentially dangerous microorganisms and also clean your humidifier on the inside. That’s not enough to fully clean a humidifier though. You’ll still have to go in there yourself and give it a good clean when necessary. 

2. Hydrogen Peroxide

Hydrogen Peroxide

The most effective to kill mold is hydrogen peroxide. Fill the reservoir with 3/4 distilled water. Then add 1/4 of volume 12% hydrogen peroxide (Amazon link) to the reservoir. Let this sit for 15 minutes and then empty out the reservoir.

That will kill the mold in the reservoir. If you have a removable filter, clean it by spraying the same diluted liquid on both sides on the filter, let it sit and rinse it out.

If there is a lot of mold in your humidifier, it’s a good idea to clean it with hydrogen peroxide, then physically clean out any mold you can see by hand and then run it again with some vinegar. That way you get rid of every last bit and all the residue will be gone as well. 

Running the humidifier with hydrogen peroxide is not a big problem since it breaks down into water and oxygen but most people probably don’t feel safe doing it with a name like hydrogen peroxide.

3. Demineralization Cartridges

If all you want is to get rid of the mineral deposits in your humidifier, these cartridges are the answer. They don’t work like the tablets that dissolve. You put these in the reservoir and leave them there. The little balls inside the cartridges (Amazon) absorb minerals and other impurities from the water so they don’t get a chance to create deposits. 

That means these things do nothing once the deposits are created. You have to start using them while everything is still nice and shiny inside the humidifier. 

However, if you use distilled water, this shouldn’t be a problem in the first place. Distilled water doesn’t have any or very minimal amounts of minerals or anything else which means you won’t get any deposits in the first place. 

This doesn’t necessarily get rid of mold but will reduce the growth because there are fewer nutrients for it in the water.

4. Lemon Or Lime Juice

A tablespoon of lemon or lime juice will help keep bacteria and mold at bay while also spreading a  pleasing fresh smell. It does pretty much the same as vinegar but it smells nicer but is also quite a bit more expensive. 

Lemon Juice

How To Prevent Mold In A Humidifier

A humidifier is the perfect spot for mold to grow. It’s humid and usually warm. Mold spores are just in the air in many places and they can get anywhere. That means the reservoir and other moist parts of a humidifier can be quite susceptible to mold. There are some things you can do to reduce mold growth though. 

The first thing you should do is regular cleaning. Using hydrogen peroxide to clean the reservoir regularly is a good idea. Let it sit for 30 minutes and then empty out the reservoir. Adding some vinegar or lemon juice and running the machine also helps. Even if you don’t notice anything yet, stuff might be growing in your humidifier and regularly using some of the things above help prevent the problem getting worse. 

Using distilled water reduces the likelihood of introducing mold into the reservoir. Tap water can have spores in it and distilled water is much less likely to. 

If you have a humidifier with a filter that can be cleaned, clean it regularly. At least clean it weekly and before use if you haven’t used the humidifier in a while. 

In the end, it’s a moist place and it’s not possible to completely prevent any mold from growing. So regular cleaning and adding some things to your water helps prevent it becoming a problem.

No Essential Oils

Humidifiers vaporize water. They can’t vaporize oils into small droplets. That means that anything oil based can not be added to a humidifier. This will gum up the insides of the machines and likely break it. Maybe not immediately but humidifiers aren’t made to handle things like essential oils and over time it will end badly. Even if some essential oils could work against mold, it is not a good idea to use them for this purpose. 

That means no;

  • Essential oils
  • Vicks
  • Other Chest rubs & balms
  • Extracts (usually extracts are oils)

If you want to use these kinds of additives, maybe for a cold, congestion or just because it smells good, it’s better to use a steam inhaler or essential oil diffuser. Those appliances are built to handle those oil based additives and won’t get gunked up like a humidifier. 

It can also do damage to the plastic parts inside a humidifier. 

Of course you could use both an oil diffuser or inhaler and a humidifier at the same time if you want the benefits of both. As long as they’re in different appliances, there is no reason you couldn’t run both at the same time. 

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