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Do CPAP Machines Need Distilled Water?

CPAP machines are medical devices that are commonly used to treat sleep-related respiratory disorders like sleep apnea. These machines often contain humidifiers, which are small water tanks that add moisture to the air. This is beneficial for users because the lungs function best with moist air1 – during normal nasal breathing, the nose will warm and humidify the air, but CPAP machines often deliver air so fast to the nasal passages that they don’t get a chance to do this2

When you’re using a CPAP humidifier though, it’s important to only use distilled water in it. We’ll look into why this is so that you’re equipped with the necessary knowledge of how to properly and safely use your CPAP machine.

What Is a CPAP Humidifier?

Most CPAP machines either have built-in humidifier tanks, or the ability to attach an external one. These tanks add moisture to the air3 that is delivered through the mask that’s attached to the machine. Humidifiers can be heated or non-heated; heated humidifiers can add more moisture than non-heated ones.

What Is Distilled Water?

Distilled water is a form of purified water that has gone through a process called distillation. After the water has been boiled, the water vapor is collected and condensed back into liquid form, which eliminates most of the impurities that may have been present in the original liquid. 

Distillation is considered highly effective at removing viruses, bacteria, chemical contaminants4 and minerals5. You can purchase distilled water online or in grocery stores and pharmacies. There’s also the option to purchase a distillation machine to distill water at home. 

Why Use Distilled Water in Your CPAP Machine?

Manufacturers advise using distilled water in your CPAP’s humidifier reservoir because the majority of minerals have been removed. Mineral deposits can build up in the device6, causing it not to work properly. Tap water can contain low levels of microorganisms, which are safe to drink because they’re killed by stomach acid when ingested, but these organisms can cause harm if they enter the airways7

Can You Distill Your Own Water? 

You can make distilled water at home by using a specialized countertop device or by boiling water on the stove.

Take the following recommended steps8 when making distilled water using the stovetop method:

  1. You will need a large stainless steel pot with a clean lid, tap water, an oven-safe glass bowl, a working stove to place the pot on, and ice. 
  2. Fill the large pot halfway with tap water.
  3. Place the bowl inside the pot so that it’s floating on top of the water.
  4. Heat the water on the stove until it’s at a low and steady boil.
  5. Put the pot lid upside down on top of the pot, filling that lid with ice. 
  6. Allow the ice to create a steam that will drip down into the bowl.
  7. The bowl should fill with water but do not let the pot fully dry from boiling.
  8. Turn off the stove and let everything cool.
  9. Remove the water from the bowl, placing it into a water container for storage.

Distilling water at home is fairly simple, though rather time-consuming, so some people may prefer to buy bottles of distilled water for their CPAP device.

Can You Use Tap Water in Your CPAP Machine?

Medical disclosure: You should not use tap water in your CPAP machine.

You should avoid using tap water in your CPAP machine. The reason for this is that tap water contains small amounts of pathogens that are harmless to drink as they’re killed by stomach acid. However, breathing in these pathogens can lead to serious or deadly infections.7 Tap water also contains minerals that can build up in the machine, causing it to malfunction.6

Unfortunately, recent research9 reveals that 42 percent of people think that tap water is safe to use in respiratory devices like CPAPs, which means that many people are unaware of the dangers of doing so.

Can You Use Other Types of Bottled Water in Your CPAP Machine?

You might think that regular bottled water is safer to use in a CPAP since it’s not tap water. However, distilled water (bottled or not) is the only type of water that should be used in a CPAP humidifier.

  • Purified Water – Distilled water is the only type of purified water that should be used in a CPAP machine, as it’s the only one that has had all the minerals removed. Water purified via reverse osmosis10 or UV treatment11 will have harmful bacteria removed but may still contain a small amount of minerals that can damage your device.
  • Spring Water – Spring water12 contains naturally occurring minerals, making it unsuitable for use in a CPAP machine.
  • Mineral Water  – As its name suggests, mineral water has a high mineral content, so it should not be used in a CPAP humidifier.12

Frequently Asked Questions

What is a CPAP humidifier?

A CPAP humidifier is a water tank that’s either built-in or externally attached to a CPAP machine. Its purpose is to add moisture to the air delivered by the CPAP, which makes it easier for the lungs to function.1

How to travel with a CPAP machine and distilled water?

TSA guidelines13 state that CPAP devices can be carried onboard a plane with you, although the device itself must be removed from its case when passing through the X-ray. You can bring a clear plastic bag to protect the device from germs while being scanned, and the mask and tubing can remain inside the case.

If you’re worried about not being able to find distilled water at your destination, you can pack bottles in your checked baggage. Any distilled water in your carry-on bag must be placed into bottles that don’t exceed 3.4 ounces, and these must fit into a 1-quart size clear, plastic Ziploc bag.

Can you use reverse osmosis water in a CPAP machine?

Purifying water using reverse osmosis removes 90 to 99.9 percent of minerals.11 However, distilling water also removes other contaminants like metal and bacteria14. Since both experts and manufacturers advise using distilled water specifically, that’s what you should stick to.

Lisa Bowman

Lisa Bowman


About Author

Lisa is a content writer for Sleep Advisor, which combines two of her greatest passions – writing and sleeping. She can also be found writing about fitness, sustainability and vegan food.

Combination Sleeper


  • 1. “Mouth Breathing”. Cleveland Clinic. Last modified April 11, 2022.
  • 2. “Humidity and CPAP.” Advanced Respiratory Care Network. Webpage accessed November 7, 2023.
  • 3. “Understanding PAP”. Harvard Medical School. Last modified April 16, 2021.
  • 4. “A Guide to Drinking Water Treatment Technologies for Household Use”. Centers for Disease Control and Prevention. Last modified March 1, 2023.
  • 5. “Bottled Water Everywhere: Keeping it Safe”. U.S. Food and Drug Administration. Last modified April 22, 2022.
  • 6. Dula, Stephanie. “Should I Use Tap or Distilled Water for My CPAP Humidifier?”. CPAP Supplies. 2022.
  • 7. Chavez, Janelle. “Tap water isn’t safe to use in neti pots and other home medical devices. Here’s what to do instead”. CNN. 2023.
  • 8. “CREATING DISTILLED WATER FROM TAP WATER”. Chest Foundation. Webpage accessed January 7, 2024.
  • 9. Miko, Shanna., et al. “(Mis)perception and Use of Unsterile Water in Home Medical Devices, PN View 360+ Survey, United States, August 2021”. Emerging Infectious Diseases. 2023.
  • 10. “Reverse Osmosis and Removal of Minerals from Drinking Water”. The International Water Association. Webpage accessed November 10, 2023.
  • 11. Purwoto, S., et al. “Drinking Water Processing Using UV Rays”. IOP Conference Series: Earth and Environmental Science. 2022.
  • 12. Quattrini, Sara., Pampaloni, Barbara., Brandi, Maria Luisa. “Natural mineral waters: chemical characteristics and health effects”. Clinical Cases in Mineral and Bone Metabolism. 2017.
  • 13. “Am I allowed to carry my CPAP machine onboard the plane, do I have to remove it from my carry-on?” Transportation Security Administration. Webpage accessed November 10, 2023.
  • 14. Woodard, John. “Reverse Osmosis vs Distilled Water”. Fresh Water Systems. 2024.