Can I Use Reverse Osmosis Water in My Resmed CPAP?

If living with obstructive sleep apnea (OSA), you know how vital a CPAP (Continuous positive airway pressure) machine is. It is the key to more comfortable sleep therapy.

The device delivers pressurized air through a mask to soothe your airways and prevent irritation.

CPAPs come with heated humidifiers that use distilled water to relieve the dryness caused by CPAP therapy.

In this post, we discuss the type of water you can use with a CPAP humidifier as well as the benefits of the machine. You’ll also learn whether you can use reverse osmosis water in your Resmed CPAP.

Why Use a CPAP Humidifier?

Can I Use Reverse Osmosis Water in My Resmed CPAP

Humidification from the machine offers comfort by adding moisture to the air that passes via your CPAP machine. It helps relieve irritation from the nose, mouth, and throat.

If you find the airflow too cold, heated CPAP tubing can be of great help. The moisture can help break up nasal obstructions and congestions caused by allergies and colds.

Can I Use Reverse Osmosis Water for My Resmed CPAP?

Yes. Although distilled water is the only type of water recommended for CPAP machines, you can use reverse osmosis water as an alternative.

Reverse osmosis water is devoid of minerals and other contaminants that could impede the machine’s ability to work as expected.

All you need to do is regularly change the filters of your RO system to ensure that minerals and bacteria are eliminated from your water before using it in the CPAP.

Why is Distilled Water the Best for CPAP?

Most manufacturers recommend distilled water as the best type of water to use in a CPAP machine. This is because the water is safe for your health and that of your CPAP machine as well.

Distilled water is created through distillation. Regular water is turned into gas and condensed back into liquid. The process removes all inorganic compounds and microorganisms.

After the distillation process is complete, only pure water is left behind.

The distilled water is vital for your CPAP machine because it is free of bacteria and minerals such as calcium, magnesium, potassium, and phosphorous.

Calcium and magnesium build up scale if not removed from the water. Limescale causes damage to CPAP machines and reduces their lifespan.

Any bacteria in the water running through the CPAP can be harmful to your health since you risk inhaling them.

The amount of distilled water you’ll need for your machine depends on the size of its chamber. The average is usually 16 ounces, a convenient size for most single-use bottles.

You can also choose to use larger size bottles, e.g, 5-gallon bottles, to ensure you always have a supply of pure water for your sleep apnea machine.

Is it Safe to Use Bottled Water in My Resmed CPAP?

It depends on the type of bottled water you intend to use. You can only use the water if you are sure that it’s purified.

Note that bottled water does not denote distilled. It is a broad category with different flavors. Just like juice is a type of drink, there are different variations.

Bottled water can be:

  • Mineral water
  • Spring water

Mineral Water: Mineral water comes from underground sources and is naturally rich in minerals such as calcium and magnesium.

Therefore, bottled mineral water leads to limescale buildup in the water chamber and can damage your CPAP machine. With time, the damage reduces the lifespan of the machine.

Spring Water: Spring water comes from a spring, which could be at the surface or underground. This water is also rich in minerals.

In the US, spring water is not allowed to be modified or treated.

The amount of minerals present varies from brand to brand now that the water is sourced from different springs.

Note that since the water isn’t treated, it can also contain contaminants.

You should, therefore, never use spring water in your CPAP since it could damage the machine over time. You also don’t want to inhale contaminants that could be present in the water.

What Happens if I Use Tap Water in My CPAP?

It’s not advisable to use tap water in your CPAP, although it’s the most convenient choice. The properties of tap water vary from place to place since different water treatment procedures are utilized.

It’s unclear what type of minerals are in the tap water.

However, should you find yourself in a situation where distilled or RO water isn’t an option, you can use tap water.

Before using the water, boil it for about 20 minutes and allow it to cool. Once it has reached room temperature, you can safely use it in your CPAP.

Note that boiling the water isn’t a long-term solution. The quality of this water isn’t anywhere near that of distilled water, but it makes a good alternative.

Remember to clean your CPAP machine thoroughly after you get access to pure water to prevent scale buildup.

How About Well Water?

Using well water in your sleep apnea machine is strongly discouraged. There are reports of lung disease connected to using well water in the machine.

You might also ingest harmful parasites from the water.

Other Substances to Avoid in Your CPAP Water

The list of substances to add to a CPAP humidifier is very slim: distilled water only.

Always remember that your lungs are exposed to any substance added to the unit’s chamber. Therefore, you should avoid harmful solvents like perfumes, alcohol, bleach, antibacterial soaps, and ammonia, among others.

You should also never place essential oils directly in the machine. Only use the products recommended explicitly for CPAP aromatherapy to relieve congestion and aid in relaxation.

Where Can You Buy Distilled Water for Your CPAP?

Depending on where you live, you can purchase distilled water at a local pharmacy or grocery store. It is usually sold in large one-gallon jugs.

You can also avoid the long trips to the store by ordering the water from a reputable online store.


Although you can use RO water in your Resmed CPAP, try as much as possible to use distilled water. It is the safest and best option recommended by all CPAP manufacturers.

Consider reverse osmosis only if you can’t get access to distilled water.

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