Can You Use Reverse Osmosis Water in a Humidifier?

Humidifiers are beneficial devices that can prove to be your best friend if you live in a place with low humidity. They serve their purpose by adding water particles to every air molecule that comes in contact with the device’s spray. The overall moisture is increased by conventional flows.

For a humidifier to work optimally, it needs clean water. That is why humidifier manufacturers suggest using distilled water or demineralized water. But can you use reverse osmosis water as an alternative to purified water?

If you’re thinking about this question, you’re in the right place. In this article, I’ll explain everything you need to know about using RO water in humidifiers.

Can I Use Reverse Osmosis Water In My Humidifier?

Yes, you can use reverse osmosis water (RO water) in your humidifier, but only as a last resort if you don’t have access to distilled water and the only other (bad) option is to use tap water.

Reverse osmosis is an essential process for turning contaminated water into drinking water. We’ve already mentioned that humidifiers need water as pure as possible to reach its full potential.

If you’re in a pinch, reverse osmosis water can work well if there are no problems with the humidifier and the water itself has no issues. You should also note, however, that osmosis isn’t always perfect. It removes about 95 percent of all minerals and impurities. Therefore, some salts and other minerals remain in the water in negligible amounts.

Although it’s good, reverse osmosis water isn’t ideal for humidifiers. You should avoid it as long as possible because the chances of it having adverse effects are low. This is especially important if the water source you take the water from contains a lot of impurities and minerals. These mineral deposits could affect the humidifier’s mist and damage your humidifier over time.

Can Reverse Osmosis Water In Humidifier Cause Allergic Reactions?

No, pure reverse osmosis water is unlikely to cause allergic reactions.

I’ve already mentioned a slight chance of adverse effects with RO water. While most people show absolutely no reaction to the impurities in the air, people who’re sensitive to dust may show allergic reactions to the mist mixed with reverse osmosis water.

The main reason is that reverse osmosis water contains a small amount of dissolved minerals. These minerals can also easily attract germs and bacteria from the air if left inside the humidifier tank for a long time.

If there are sensitive and allergic people in your household, you should refrain from using RO water and bottled water. You should also clean your humidifier with vinegar and remove the mineral build-up in the tank regularly to avoid possible problems

Does It Matter For Humidifier That RO Water Is Acidic?

While tap water is always alkaline, reverse osmosis water is acidic. This is because the mineral cartridge used in water treatment adds small amounts of calcite to the water. When the impurities are removed from the water, the taste changes significantly.

The calcite serves to bring the water to an acceptable level. However, this lowers the pH of the water, which allows hydroxonium ions to form. This is the main reason why reverse osmosis water tends to be acidic.

Note that while reverse osmosis water is acidic, this acidity is by no means harmful. If anything, it’s better for drinking than pure water without minerals or even water from the water filter.

Apart from the disadvantage mentioned above, the acidic nature of the water has no adverse effects even if you use it in humidifiers.

How To Clean Your Humidifier from Reverse Osmosis Water?

Let’s say you’ve used reverse osmosis water in your humidifier in the past. Now that you know the drawbacks and don’t want to take any chances, you should clean the humidifier to remove all traces of reverse osmosis water.

Removing the reverse osmosis water is quite simple. You can use vinegar to clean your humidifier. And all traces of the reverse osmosis water will be gone. Be careful not to use too much of the hydrogen peroxide solution.

Related reading: Do You Put Hot Water or Cold Water in a Humidifier?

Frequently Asked Questions

What is reverse osmosis water?

Reverse osmosis water is water produced using the reverse osmosis (RO) method. The RO system purifies water by removing impurities such as heavy metals (lead, mercury), chlorine, and other pollutants. A reverse osmosis system utilizes a semipermeable membrane that works to filter out the contaminants in the water. The process works by forcing the contaminated water through the membrane, trapping the pollutants while allowing the purified water to pass through. Once the reverse osmosis process is complete, the water is safe to drink as it is free of contaminants.


In conclusion, reverse osmosis water is a safe and viable option for use in your humidifier.

This type of purified water is free from minerals like calcium and magnesium and contaminants, which can help prevent mineral buildup in your humidifier and improve its overall performance.

Reverse osmosis water is also a cost-effective alternative to the best water types for use in humidifier – distilled or demineralized water, which can be more expensive and harder to find.

However, keep in mind that while reverse osmosis water is safe to use in your humidifier, it may not be as effective at preventing mineral buildup as distilled or demineralized water. It’s important to clean your humidifier regularly and refer to the user manual for any specific recommendations on the type of water to use.

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