Do You Have to Use Only Distilled Water in the CPAP Humidifier?

Tap water may cause mineralization and be risky with travel

People with sleep apnea stop breathing during sleep. This can happen many times in one night.

The condition is often treated with a continuous positive airway pressure (CPAP) machine. This device works by delivering a flow of pressurized air through a mask to keep airways open.

CPAP machines often have heated humidifiers. The instructions typically say you should use distilled water in the humidifier.

This article discusses the benefits of a CPAP humidifier. It also looks at when and why you should use distilled water in your CPAP machine.

Using distilled water in your CPAP humidifier.

Verywell / Brianna Gilmartin

Benefits of a CPAP Humidifier

A heated humidifier can make your CPAP machine much more comfortable. It can reduce dry mouth and congestion.

A CPAP humidifier prevents dryness, especially in the nose and sinuses. This may reduce the risks of:

  • Infections
  • Nasal congestion
  • Inflammation
  • Nosebleeds

Outside factors may impact how often you use your humidifier. Local climate and personal preference may all play a role. Depending on your manufacturer, you may be able to change the temperature and humidity levels.

If you're using standard tubing, condensation within the tubes may cause problems. This is sometimes called "rainout." It is more of a problem when your bedroom is cool.

ClimateLine heated tubing can help prevent this problem when you turn up the humidity.

When possible, avoid letting the humidifier run dry. This can cause the motor to overheat. Refilling the water reservoir every night can prevent this.

Can You Use Tap Water With a CPAP Humidfier?

The safety of your CPAP machine depends on the quality of the water you use. Tap water may contain microbes, minerals, and chemical contaminants.

You can kill microbes by boiling water. Boiling does not remove minerals or chemical contaminants, though.

Minerals like calcium, magnesium, and iron are what make your water "hard." If they are in the water you use in your humidifier, they will cause a build-up of mineral deposits, called scale. This could damage the machine.

Filtering can remove some of the minerals. It may not remove microbes or other chemicals, though. Bottled, distilled water is the safest option.

Distilled water prevents mineral deposits. This extends the life of the water tub. Still, you will need to replace the water tub every six months or so anyway. For this reason, it may be less important to extend the life of the water tub.

It's fine to occasionally use tap water to clean your CPAP machine.

Most manufacturers recommend using distilled water in a CPAP humidifier.

What You Shouldn't Put in Your CPAP Humidifier

Remember that you are exposing your lungs to the water you put in the humidifier. This is a good reason to clean it regularly. Do not add substances to the water that might be harmful to breathe. Examples include:

  • Perfumes
  • Colognes
  • Scented oils

When cleaning your humidifier, don't use:

These substances could damage your lungs. You should also avoid using water softeners and descaling agents in the water tub.


Any chemicals you put in the humidifier tub will end up in your lungs. Avoid adding perfumes or other scented products to the water, and don't clean the humidifier with harsh cleaning agents.

What Water Should You Use When Traveling?

When traveling in areas with poor water quality, use distilled water in your humidifier. If the water is not safe for you to drink, it is not safe to put in your CPAP humidifier. In this case, using distilled water will limit your exposure to harmful substances.

For example, a few people in Louisiana who used tap water in Neti pots developed a rare infection of the brain caused by an amoeba. This condition is usually fatal and treatment is almost always ineffective.

The same risk has not been demonstrated with the use of a CPAP humidifier. Still, it is a good example of how dangerous microbes can sometimes be found in tap water.

Where to Buy Distilled Water

You can buy distilled water at many grocery stores. It is not the same as regular bottled or filtered water, so read the label carefully.

Outside of the United States, distilled water may be limited to specialty stores. In some cases you may need to buy it from a hardware store.


Using the humidifier in your CPAP machine can help prevent problems in your nose and sinuses.

Some tap water may be safe to use in your CPAP humidifier, but the safest option is distilled water. Tap water sometimes contains minerals that will build up inside your machine. It may also contain dangerous microbes and chemicals.

Avoid adding things like perfumes or scented oils to your humidifier water. Avoid harsh cleaning agents when cleaning your device.

When traveling to areas with unsafe water, always use distilled water. 

A Word From Verywell

If there is any doubt about the safety or quality of the water supply, use distilled water in your CPAP humidifier. This is especially true if you are traveling in parts of the world where the water is unsafe.

If you don't have access to safe water, you may want to consider using the CPAP without the humidifier.

Frequently Asked Questions

  • Is it possible to make your own distilled water for a humidifier?

    Yes, it is possible to make your own distilled water at home by creating a condensing steam. A large pot with lid, a heat source, a bowl, and ice cubes are the necessary supplies to create the condensation (water vapor).

  • Can a CPAP be used without water?

    Yes, you can use a CPAP machine without the humidifier element, and therefore, without water. The machine will continue to work and will simply use dry air.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Quinn A, Shaman J. Health symptoms in relation to temperature, humidity, and self-reported perceptions of climate in New York City residential environmentsInt J Biometeorol. 2017;61(7):1209‐1220. doi:10.1007/s00484-016-1299-4

  2. Chin CJ, George C, Lannigan R, Rotenberg BW. Association of CPAP bacterial colonization with chronic rhinosinusitis. J Clin Sleep Med. 2013;9(8):747-50. doi:10.5664/jcsm.2910

  3. Helmenstine AM. How to make distilled water at home or while camping. ThoughtCo.

  4. Sleep Foundation. CPAP humidifiers.

By Brandon Peters, MD
Brandon Peters, MD, is a board-certified neurologist and sleep medicine specialist.