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Can You Use Tap Water in a Humidifier

Can You Use Tap Water in a Humidifier?

Humidifiers can be helpful to your breathing, especially in the dry months of winter. However, they can be just as harmful if you do not fill them with the correct type of water. Spring, distilled, bottled/purified, and tap water all have different impacts on a humidifier and your health.

You might think that if your tap water is safe to drink, then it is safe to use in appliances such as humidifiers. This is not always the case.

Yes, you can fill the water reservoir with tap water, but tap water may be the worst type of water you can fill your humidifier with because it can shorten the lifespan of your humidifier and pose health risks to your family.

What Type of Water Is Best for a Humidifier?

What Type of Water Is Best for a Humidifier

Many humidifiers tend to distribute minerals and microorganisms into the air along with water. Both of these things can cause health problems if inhaled in high amounts. The best way to keep your air clean when using a humidifier is to use water with low mineral levels.

While spring water goes through treatment for harmful bacteria and other things that can make you sick, it doesn’t go through mineral removal treatment. Companies generally preserve minerals in spring water because many people don’t usually consume the correct amount of nutrients needed to stay healthy.

Tap water is the cheapest water for a humidifier because you have easy access to it. The tap water in some areas has much higher levels of minerals compared to other types of water.

This is because it doesn’t go through mineral removal treatment. Due to the high mineral content, do not use it in a humidifier. The high mineral amount will impact your humidifier and possibly your health.

Bottled/purified water is a slightly better option to use in your humidifier. Bottled and/or purified water goes through a filtration process to purify contaminated water. During this purification process, some minerals get removed from the water, but not all of them. Although bottled water has fewer minerals than spring and tap water, it isn’t the best choice.

Distilled water goes through a boiling and evaporation process to filter it. During this process, a large number of minerals get separated and removed from the water. Due to distilled water having the lowest amount of minerals compared to other types of water, it is the best water for humidifiers.

Problems With Using Tap Water in a Humidifier: Is It Safe To Use Tap Water In A Humidifier?

White dust

humidifier white dust

When an ultrasonic humidifier releases mist into the air, it releases small particles called particulate matter. Particulate matter contains both solids and liquids. In the case of a humidifier, the minerals and microorganisms are the solids, while the water is the liquid.

Particulate matter has two categories. There is particulate matter that is less than 10 micrometers and particulate matter that is less than 2.5 micrometers. Particulate matter that is less than 2.5 micrometers is dangerous. These particles can enter your lungs and then eventually make their way to your bloodstream.

When you fill your humidifier with water, 95% of the particles released are less than 2.5 micrometers. They’re closer to around 1 micrometer, making these particles extremely tiny and harmful. 

In addition, when the mist from your tap-water-filled humidifier settles, the small particles leave a white film of mineral dust. The dust essentially pollutes the air and surfaces in your home.

But you can prevent this problem by using an evaporative humidifier or a vaporizer that doesn’t break down water into water droplets.

Mineral buildup, mold, and bacteria

mold in humidifier

With the use of tap water, you are breathing in relatively higher amounts of mineral dust compared to if you used a different type of water. Drinking mineralized tap water is fine, but inhaling minerals is where it turns into a problem. 

Using tap water in your humidifier can also create a film or crust inside of the humidifier itself. This film is the perfect breeding ground for bacteria, mold, and other irritants. Bacteria and mold can be detrimental to your health depending on how long you are exposed to them. 

The effects of inhaling bacteria and mold particles can lead to flu-like symptoms and sometimes infections of the lungs. People diagnosed with asthma can have more severe symptoms and reactions.

Shorten lifespan

Using tap water can clog the parts in the machine, stopping it from producing mist and causing other malfunctions. You may have to get a new one very soon. If you think using distilled water is costly, you can make it at home.

The use of tap water in your humidifier is generally safe if you clean the device regularly Never take a chance on your or your family’s health.

Can You Put Spring Water or Bottled Water in a Humidifier?

Spring water and tap water are quite similar in terms of mineral content. This is because they both come from natural sources such as lakes, rivers, and the ground. Do not use spring water in a humidifier due to its mineral content. Just because the label says it is “spring” or “natural” water, it does not mean that it is better.

As for bottled/purified water, it is not horrible. It is a little better than spring and tap water, however, it still isn’t what you should be using in your humidifier. Although bottled/purified water having a lower mineral content is a good thing, the mineral content still isn’t low enough. 

Can You Make Your Tap Water Safer?

dehumidifier demineralization cartridges

There are options to filter your tap water further so you can have usable water for your humidifier. Depending on your humidifier brand, there are demineralization cartridges and other filters you can put inside your humidifier. Always check to see what is compatible with the humidifier you have.

An issue with filter cartridges is that they can get quite pricey. You are better off buying distilled water because it is much cheaper than buying extra filtration parts that need to be replaced.

There is also the issue of the filters not working. There isn’t much evidence that the filters work well enough to keep mineral dust out of the air. If you try this method, pay attention to see if mineral dust appears after using your humidifier. If there is mineral dust, stop using the cartridge and switch to distilled water.


Using a humidifier is okay to do, but the type of water you use can cause issues. When shopping for a humidifier, you may notice that many brands say tap water is okay to use. But, humidifier brands don’t take water hardness into account. The humidifier itself might be able to handle your tap water but your lungs may not.

The safest option is always distilled water due to its purification and mineral removal process. 

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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 more than 150 products in person, including 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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