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What Water To Use In Your Humidifier

What Type of Water to Use in Your Humidifier? [All Types of Water Analyzed]

For many of us, a humidifier is a handy equipment to combat dryness at home. Otherwise, the winter months can be an agony.

There are many considerations when using a humidifier and what type of water to use is the most important.

Which type of water is the best for a humidifier among filtered, purified, distilled water, and tap water? You’ll find out if you keep reading!

Why is the type of water important for a humidifier?

A humidifier improves indoor humidity by adding water particles to the air. When the water vapor enters the room, we and our pets will inhale it.

If the water contains harmful contaminants, like mold spores and bacteria, they will also get into our bodies, posing health risks to us. 

In addition, it will reduce the lifespan of your machine. An ultrasonic humidifier breaks water down into tiny water particles through the high-frequency vibration of a diaphragm. If the impurities clog the diaphragm (also known as the transducer), the machine will stop working. 

An evaporative humidifier raises the humidity level by evaporation. It has a wick that filters out impurities, making it less sensitive to water quality. 

However, water contaminants will eventually increase the frequency of filter replacement and cause the machine to stop working.

Different types of water contain various components. The one with the fewest impurities would be best for both the humidifier and us.

Tap water is not the best choice for a humidifier 

Every day, we drink tap water. As a result, we will assume that adding tap water to a humidifier is not a problem.

While using tap water in a humidifier will not wreak havoc in a short time, it can cause many issues sooner or later. 

As you may be aware, tap water contains dissolved minerals. These substances will settle in the tank and form buildups, which may serve as a food source for mold spores and bacteria.

In addition, tap water is not germ-free. These germs will proliferate in the tank as well. 

When the machine is turned on, these dangerous microorganisms disperse into the air. Mineral deposits will clog the machine and settle on the furniture as “white dust.” White dust is not toxic, but it may cause allergic reactions in some people.

Since tap water consists of so many impurities, it is not the best option to go for. 

Check more details about adding tap water to a humidifier here. 

Soft water is better than hard water 

Depending on the region you live, the tap water can be hard or soft. When water contains less than 60 mg/L (milligrams per liter) of calcium carbonate, it is soft water. 

While tap water is not recommended, soft water is preferable to hard water. The fewer minerals there are, the less dust and microorganism growth you will have to deal with.

To convert hard water to soft water, some people will use a water softener system. Nonetheless, the mineral is replaced by sodium, making softened water more suitable for household appliances than drinking.

Soft water still contains germs and minerals, which is not the best type of water for humidifiers either. 

Purified water is better than filtered water for a humidifier

filtered water in humidifier

In some cases, purified water and filtered water are interchangeable. But purified water is usually purer than filtered water. 

This is due to the fact that filtered water is the water that comes from tap water or spring water and has gone through one or a few filters. In contrast, purified water must undergo a strict purification process such as reverse osmosis or deionization and should be free of almost all chemicals. 

As a result, 99% of contaminants have been removed in purified water, whereas filtered water has a higher concentration of minerals and microorganisms.

Therefore, purified water is better to add to a humidifier than filtered water.

Distilled water is the best type of water for a humidifier 

Until now, it seems that purified water is an ideal type of water for humidifiers. No, distilled water is even better than purified water

Distilled water refers to water that is collected through a distillation process. When the water is boiled, the water will turn to water vapor, leaving all the impurities behind. It is free of germs and chemicals. 

Since purified water may still contain a trace of minerals and microbes, let’s say 1% contaminants, distilled water technically eliminates the chance of buildups. 

Note that mold spores, dust, and dirt can enter the device through the outlet. You should clean the humidifier on a regular basis even though you use distilled water.

How about dehumidifier water?

Some people wonder if they can put dehumidifier water in a humidifier. Yes, you can; it is much better than tap water. 

A dehumidifier collects water through condensation, which converts moisture particles in the air into liquid, similar to the final step in the distillation process. This ensures that the condensed water is mineral-free, which is ideal for a humidifier.

However, contaminants in the air may pollute the condensate, and the evaporator coil may leach metal.

If you do this, avoid using stagnant dehumidifier water because the water bucket could be a breeding ground for mold growth.

Keep an eye on the water temperature 

Even if warm mist humidifiers disperse the warm mist, it doesn’t mean you can put hot water in a humidifier directly. 

No matter which type of humidifier you have, you can only use cold water in a humidifier.

Cold water is safer for your kids and pets since it prevents potential burns. Meanwhile, hot water could ruin the parts in a cool mist humidifier as they are not designed to withstand hot water. 

Furthermore, hot water may contain more minerals, which can gradually clog the machine.


This article has discussed various types of water for humidifiers and concluded that distilled water is the best option.

This is due to the fact that distilled water is free of minerals and chemicals, resulting in far fewer buildups and health risks for us. Buildups can shorten the machine’s lifespan and serve as a breeding ground for bacteria and mold.

Please insist on filling your humidifier with distilled water if you want to get the most out of it.

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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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