Why you should use distilled water with your CPAP machine

Distilled Water and CPAP

Moderate to severe sleep apnea is serious business. Continuous positive airway pressure (CPAP) treatment can really help but you’ll want to make sure that that you are using it properly. Today we are going to talk about why you should use distilled water with your CPAP.

We’ll let you know what happens when you use regular tap water, what happens if your CPAP runs out of water, and give you a few tips for extending the ‘mileage’ and efficacy of this sleep-saving device.

Your CPAP helps you to sleep soundly, safely, and comfortably so why not help it along?

Why distilled water is the best option for your CPAP

The reason that manufacturers of these machines recommend distilled water as the best option to use for your CPAP is because the distilling process makes the water very, very clean. The water is turned into a gas and condensed back into a liquid, so that the following organisms and inorganic compounds may be removed:

  • Magnesium
  • Potassium
  • Bacteria
  • Heavy metals
  • Calcium

What’s left is quite close to completely pure H2O, which is why distilled water is also popular with laboratories and hospitals as well. It’s sterile and so it is ideal.

What is Distilled Water?

Distilled water is one type of purified water that has been through a process to remove anything it is that is not water. The process is the water is placed into a container or pot. Then it is boiled into vapor and condensed back into liquid in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container.

After this process, all that is left is the water. The taste of distilled water is that it has no taste, which is very different than regular drinking water. This may sound crazy to someone who has never tasted distilled water before, because drinking water doesn’t have much of a taste either. But pretty much anyone can do a blind test and sense the difference between distilled water and regular water.

Having all the minerals and deposits removed from the water might make it taste bland, but it will really make a difference when using it with your CPAP or BIPAP machine..

What happens when you use regular tap water?

Tap water is not a good fit for your CPAP. While it’s healthier to drink than most bottled waters, the reason for this is the same reason that you don’t want to put it in your CPAP. Basically the water goes through a 4-part process like this:

  • Chemicals that can bind with waterbourne compounds are used to create a mass known as ‘floc’.
  • The density of the floc makes it sink to the bottom of the water as a removeable layer during a sedimentation process.
  • With the floc removed, the water is filtered through mediums such as charcoal, sand, and gravel to minimize germs, bacteria, toxic chemicals, and dissolved particles in the water.
  • A chlorine disinfection completes the process to provide potable drinking water

As your CPAP is a specialized humidifier, by heating up tap water you are opening up the device to the buildup of mineral residues, not to mention anything untoward that might become part of the vapors you are inhaling. Tap water is great to drink but it’s simply not a good idea to use it in your CPAP.

Although tap water isn’t recommended for using CPAP, if you are in a pinch, using tap water for one or two nights is not a big deal. You would want to wash your water tank in the humidifier really well though. I have a thorough article about using tap water and CPAP that will provide more information.

Is it OK to use CPAP without water?

We get asked quite often what will happen if the CPAP runs out of distilled water during the night. Is it going to destroy the machine? While it’s not good for the CPAP the good news is that if it runs out of water during the night it will still function, but you won’t be getting vapor from it.

This might well wake you up, but if not, just be sure to refill it at your soonest convenience so that your CPAP may function as-designed.

I have a great article about using a CPAP without water that goes over the pros and cons and everything else you need to know.

Some good tips for getting the most out of your CPAP

Keeping your CPAP filled with distilled water will keep proper pressure in the device to help ensure that you get the purest of vapors flowing continuously from your device but there are also a few other quick tips which you might find useful:

  • Don’t ‘customize’ your water with additives – While it might be tempting to add a little zest of aromatherapy or other additives to your distilled water, this is something that you shouldn’t do. Some additives have dyes, some oils are broken down with alcohol, and you never know if something you are adding has been clean-treated with bleach. No herbs, either, as they are not as clean as they look. Stick to distilled water and let the CPAP do its job!
  • Keep your CPAP clean – Change out your water daily so that it doesn’t have time to build up bacteria from the stagnation of the water. Also you will want to clean your humidifier once a week as per the instructions in your manual. Your CPAP is for your nighttime breathing so it’s just good sense. Take care of the CPAP and it will take care of you.
  • Replace your CPAP water tank every 6 months – Replacement times may vary so you’ll want to consult your supply schedule, but be sure that you follow its recommendations so that the CPAP that you are using is always functioning and delivering at its best.

Some final words

We hope that we’ve helped to ‘clear the air’ in regards to why distilled water is the best water for your CPAP. We’ll close with a final bit of advice that just makes good sense when it comes to water. If you wouldn’t drink it then you certainly don’t want to inhale it.

Stick with distilled water and let your CPAP do the rest!


Dan was diagnosed with sleep apnea in 2017 when he was only 32 years old. He has been using a BIPAP machine for his treatment. He hopes to provide a patient's perspective on the sleep apnea experience. Dan lives in Tampa with his girlfriend and 2 dogs.

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