What Kind of Water Can I Use in My CPAP Humidifier?

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Sleep apnea is a severe yet often underdiagnosed disease that often leads to constriction of the airways while one is sleeping, leading to symptoms like gasping, choking, or even experiencing inhibited breathing while they are asleep.

One of the most effective treatment routes for sleep apnea is CPAP or Continuous positive airway pressure therapy. The machine is designed to deliver “pressurized air” to the patient to keep their airways and breathing passages open to minimize the symptoms of sleep apnea and reduce the risks of accidental death during sleep.

This article will further explore more about the functioning of the CPAP humidifier and the kind of water you need to use in the machine for optimal functioning.

What is the Significance of a CPAP Humidifier?

Not just for sleep apnea, the use of CPAP humidifier comes with various other benefits too. From keeping the airways open to preventing congestion during rough and dry weather, the benefits are extensive.

Some of the symptoms that the CPAP humidifier can address include:

  • Sleep apnea symptoms
  • Infection
  • Nasal congestion
  • Inflammation
  • Nosebleeds, etc.

The way and intent behind using the CPAP humidifier will vary from one patient to the other. Also, the kind of humidifier you use will decide how you program and maintain it in the long run.

Why is Distilled Water Considered Ideal for CPAP Humidifier?

CPAP Humidifier


When you buy a CPAP humidifier, the instructions in the manual (in most cases) will mention using distilled water. Now, you must be sitting there wondering, “Why distilled water and not tap water?”

Let us understand basic chemistry here.

In a CPAP humidifier, the water that you pour into the machine is first heated until it reaches the point of steam. During this process, purification of the water occurs too. This leaves behind a residue of solids, minerals, chemicals, etc. The remainder of the steam or “heated water” is then used to function the CPAP machine.

When you use tap water, which is primarily unregulated and contaminated, the residue left behind after the steaming process is much more. In the long run, this might end up damaging the machine and preventing it from functioning optimally.

On the flip side, distilled water is already treated, and the unwanted chemicals and contaminants are removed. This means the residue left behind after the heating process is comparably lower in the machine.

This is one of the reasons why distilled water is universal for almost all humidifiers, neti pots, diffusers, etc.

That said, the following are the listed benefits of using distilled water in your CPAP humidifier:

  • It reduces and eliminates the growth of bacteria or other pathogens in the machine.
  • It creates optimal air pressure for better functioning of the humidifier.
  • It doesn’t consist of microbes, minerals, chemicals, or contaminants.
  • It reduces the complaints of mineral scaling and build-up inside the machine.
  • It is 99.9% purified already and contains very minimal dissolved solids in it.

Overall, if you want to get the most out of your CPAP humidifier and want to maintain and reuse it in the long run, using distilled water is mandatory.

Is Using Tap Water for CPAP Humidifier Permissible?

More than the factor of permission, using tap water will damage the CPAP humidifier sooner than you think.

Besides the longevity, even the safety of the CPAP machine relies on what kind of water you are using. In this case, using tap water is the last thing you want to do. Not only does tap water contain microbes, but it also has minerals and chemicals unsuitable for the CPAP machine.

Now, you must be thinking, “Won’t boiling the water kill the microbes?” Technically, yes. But that still leaves us with minerals and contaminants in the water, which you don’t want in the humidifier.

In the long run, the mineral deposition in the humidifier might lead to mineral scaling, damaging the efficiency of the humidifier. This is one of the reasons why distilled water is an ideal fit instead of tap water. Since CPAP humidifiers are an expensive affair, you want to ensure that you’ll be able to use the machine in the long run.

To be able to do that, you’d need to use distilled water instead of tap water. The only instance where you can use tap water for your CPAP humidifier is when you are cleaning it.

List of Items That You Shouldn’t Put in the CPAP Humidifier

The CPAP humidifier is not like your standard humidifier or mist sprayer. It is primarily used for medical conditions, meaning there are restrictions.

In standard humidifiers or diffusers, adding essential oils, etc., is permitted, but that’s not the case with a CPAP humidifier. There are a list of items that you need to avoid adding to your CPAP humidifier, including:

  • Perfumes or cologne
  • Scented oils
  • Bleach
  • Alcohol
  • Chlorine
  • Ammonia
  • Glycerine based soaps
  • Moisturising soaps
  • Antibacterial soaps, etc.

Not just in the water section, even the agents that you use for the cleaning process should be treated with caution. The last thing you want to do is end up adding an agent that’s damaging to the humidifier’s functions.

Also, when cleaning the water tub in the CPAP humidifier, you must avoid using water softeners or descaling agents. There should be clear cleaning instructions mentioned in the instruction manual. Only follow the steps mentioned there.

What Kind of Water is Ideal to Use in a Portal CPAP Humidifier?

Do the rules apply the same when you are traveling? Technically, the answer is yes. Even when traveling with your portable CPAP humidifier, you must use distilled water.

The location doesn’t matter because the water quality you put into the CPAP humidifier makes all the difference in the results you get from the therapy.

So, you want to use high-quality distilled water to prevent risks of infections and eventual damage to the CPAP machine.

Is it Safe to Use Boiled or Filtered Tap Water?

So, now you know that direct tap water isn’t favorable for your CPAP humidifier, what about boiled and filtered tap water?

Boiling and filtering the tap water mostly gets rid of the microbes. It doesn’t necessarily eliminate the minerals, chemicals, and contaminants. So, when you use boiled and filtered tap water, you enhance the risks of mineral scaling inside the humidifier, which can damage the machine.

In short, even after boiling and filtering the tap water, it isn’t clear or pure enough to be used in the CPAP humidifier.

Is it Safe to Use Bottled Water?

Bottled water is high in minerals and doesn’t have microbes or contaminants in them. But, even with the purity level, it isn’t an ideal choice for CPAP humidifiers.

The level of minerals in the packaged drinking water makes it unsafe for use in CPAP humidifiers since it leads to mineral scaling.

This fizzles down to the fact that the only “safe” option that you can consider using for your CPAP humidifier is distilled water.

How to Clean the CPAP Humidifier?

Besides the kind of water you should be using in your CPAP humidifier, the way you clean and maintain the machine makes a huge difference to its longevity as well.

There are clear cleaning instructions mentioned in the instruction manual that you must follow when cleaning a CPAP humidifier. Not following them will not only damage the machine but also lead to various performance issues.

Some of the cleaning tips to keep in mind are:

  • You don’t want to leave stagnant water inside the water tub of the humidifier, which means that you need to clear the water every day.
  • For optimal performance and reduced risks, it is ideal that you clean the water tub thoroughly once a week.
  • If your CPAP humidifier’s water tub is dishwasher safe, you can read the instructions for optimal cleaning.
  • There are instructions on how often you should replace the humidifier for optimal results. You’d have to read the mentioned regulations or follow your doctor’s advice.


CPAP humidifiers come with various benefits, and they are expensive, too. If this is your first time using the machine and you need clarification about its requirements, we have sorted it all in this guide. Since the kind of water you use in the humidifier is quintessential, you must follow the manufacturer’s instructions and use distilled water. We have explored the pros of using distilled water and the cons of using other water sources.

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