Frequently Asked Questions

The following answers deal with common questions surrounding humidification. If you have a specific, individual health concern—especially one related to your treatment—please discuss it directly with your health professional.

1. How much water should a humidifier use during a night?
2. My humidifier sometimes runs out during the night and most other nights is 3/4 empty by the morning. What is going on here?
3. I have a full face mask; will I need more water during the night?
4. I can't use my humidifier during some nights because my hose fills up with water condensation. What can I do about it and why does this happen?
5. I have heard that wrapping the continuous positive airway pressure (CPAP) hose with fabric will help with "rainout." Is this true?
6. Can I put my CPAP on top of the humidifier? Or should it only go next to it?
7. How often should I change the water in the chamber? I never seem to use it all in one night's time.
8. Does heated humidification wear out my mask and hoses faster?
9. How do I know what temperature setting to use with my humidifier?
10. If I run out of distilled water, is it ok to use tap water once in a while?
11. Should I turn on my humidifier before I go to bed to make sure the water is warm first?
12. I usually use my humidifier during only the winter months when the heat is on in our house and, therefore, the air is dryer. Am I shortchanging myself? Should I be using it all year round?
13. Is it common for insurance companies to deny coverage for heated humidifiers? Mine won't pay.
14. What are the overall benefits of humidification?
15. What are the benefits of using a warm air humidifier vs. cold? Nasal pillows vs. mask? Which is a better choice when using humidification?
16. Is humidification helpful for Upper Airway Resistance Syndrome (UARS)?

1.How much water should a humidifier use during a night?
The amount of water needed varies from one humidifier to the next, from one patient to the next, and with the temperature and humidity of the bedroom.
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2.My humidifier sometimes runs out during the night and most other nights is 3/4 empty by the morning. What is going on here?
If you mean "why does it vary from one night to the next?" it may be that you are mouth breathing or have mouth leak. If you breathe through your mouth, you let lots of air escape from your mouth. All the extra air that escapes uses up your water more quickly.
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3.I have a full face mask; will I need more water during the night?
A full face mask should not change the amount of water used each night. If you had a mouth leak before, you could have been losing lots of air and humidity through your mouth, in which case you should use less water now.
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4.I can't use my humidifier during some nights because my hose fills up with water condensation. What can I do about it and why does this happen?
This condensation is called "rainout." If your room is cold, the warmed, humidified air hits the colder room temperature and cools. When air cools, the amount of humidity (water vapor) that it can hold is reduced, which causes the humidity to "rain out." The amount of water air can carry varies with temperature: warmer air can carry more water while cold air can carry less. As warm air becomes cooler (eg, overnight), it has less capacity to carry water, so water condenses and forms droplets. There are a couple of ways to deal with this situation. (1) You can try turning your humidity level down. (2) You can raise the temperature of your bedroom at night to lessen the difference between the room temperature and the humidifier—make sure that your bedroom window is closed. (3) You can run the air tubing beneath your blankets to keep it warm. Alternatively, you can cover the tube with aluminum foil some type of insulation such as a tubing wrap. The goal is to keep the tube and its air warm.
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5.I have heard that wrapping the continuous positive airway pressure (CPAP) hose with fabric will help with "rainout." Is this true?
Yes. Wrapping the hose helps to insulate your treatment air from the lower temperature of the room, reducing "rain out."
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6.Can I put my CPAP on top of the humidifier? Or should it only go next to it?
The CPAP should always be placed either at the same level or above the humidifier to reduce the risk of water entering the CPAP machine. To further ensure water does not enter your CPAP machine; disconnect the humidifier from your CPAP machine and drain the water from it before transporting it dry.
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7.How often should I change the water in the chamber? I never seem to use it all in one night's time.
The water should be changed for each use.
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8.Does heated humidification wear out my mask and hoses faster?
No, the tubing supplied with CPAP machines can withstand far higher temperatures than the heat generated by the humidifier.
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9.How do I know what temperature setting to use with my humidifier?
Humidification temperature should be set according to your own personal preference. The setting should avoid rainout, while providing you comfortable and adequate therapy. ResMed’s new H4i™ heated humidifier delivers 30% more humidity than its predecessors—the most humidity output of any integrated device. With the full line of HumidAire™ humidifiers, the heater plate is thermostatically controlled: it will heat until the required temperature is reached and then switch off. Once you have reached the stage where the light is off, turn the dial up one setting and try it at that level. If your symptoms are not resolved, you may need to turn it up another setting. Continue in this manner until your symptoms are resolved. If you start to experience moisture in the mask tube, you need to turn it down, heat the room or insulate the tube.
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10.If I run out of distilled water, is it ok to use tap water once in a while?
Using distilled water will maximize the life of the water chamber and reduce mineral deposits. However, it is ok to occasionally use tap water to clean your humidifier. Do not use: bleach, alcohol, chlorine or ammonia-based solutions; moisturizing, antibacterial or glycerine-based soaps; and water softening and unapproved descaling agents.
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11.Should I turn on my humidifier before I go to bed to make sure the water is warm first?
If you find the air dry and irritating, then you may want to turn your humidifier on 20 minutes prior to going to bed.
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12.I usually use my humidifier during only the winter months when the heat is on in our house and, therefore, the air is dryer. Am I shortchanging myself? Should I be using it all year round?
If you are finding that you have nasal symptoms at other times of the year, then you should probably use your humidifier. The added humidification will probably increase the comfort of the air as it is more fully moisturized.
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13.Is it common for insurance companies to deny coverage for heated humidifiers? Mine won't pay.
Insurance coverage can vary. Please contact your insurer directly. If you go through your doctor and get a prescription and a letter of medical necessity (a letter that explains why you need heated humidification), it increases your chances of being reimbursed. Unfortunately, some insurance companies will not cover the cost of heated humidification.
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14.What are the overall benefits of humidification?
Up to 40% of PAP users experience nasal congestion and dryness of the nose and throat. These symptoms can be severe enough to prevent patients from continuing their treatment. Adding a humidifier to your CPAP treatment reduces symptoms of dryness and congestion, improving overall comfort and compliance. Research also shows that nasal resistance can promote mouth breathing, which in turn leads to additional dryness. Heated humidification can prevent the large increase in nasal resistance that results in mouth breathing and leaks.
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15.What are the benefits of using a warm air humidifier vs. cold? Nasal pillows vs. mask? Which is a better choice when using humidification?
Because you can adjust the level of heat, heated humidification offers greater flexibility and reduces more severe symptoms. Both nasal pillows and masks are a viable option when using humidification; however, "rainout" (moisture caused by having the humidifier turned up too high) when using nasal pillows may become more of an issue as the moisture is directed into the nostrils.
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16.Is humidification helpful for Upper Airway Resistance Syndrome (UARS)?
Humidification doesn't really help with OSA or UARS. It helps with side effects caused by CPAP. If you are already on CPAP treatment and experiencing nasal dryness/symptoms, then humidification should help decrease the symptoms. The nasal symptoms are due to the increased flow of air through the nasal passages. Humidification adds moisture to the air breathed and helps the nasal passages cope with the increased flow of air.
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