What is CPAP Rainout and How Can it be Prevented?

Have you ever woken up to water in your mask?
Ever noticed a lot of condensation in your tubing?
Has water in your hose ever stopped you from using your CPAP?

This is known as CPAP rainout. What is rainout? And why does it happen?

What’s the big deal with moisture in the air?

The normal function of the upper airway is to heat, humidify and filter the air that you breathe into your lungs.

If you have been diagnosed with sleep apnea and are using CPAP (continuous positive airway pressure), the device is blowing air into your airway all night long and you may have some leak of air through your mouth or mask (learn more about how CPAP works here or click the image below).

This can cause dry airways and inflammation.

Studies show up to 70% of CPAP users experience nasal congestion, dry nose and throat, sore throat, nose bleeds (epitaxis) or discomfort from the cold airflow CPAP (read more about the benefits of heated humidification here).

Heated humidification can reduce airway dryness and increase compliance.

What causes rain out?

If, like most CPAP users, you’re using a heated humidifier, the air is heated in the humidifier and flows through the tubing up to the mask and into your airway. As the air travels through your tubing, its temperature drops rapidly.

As the air cools, the moisture from the air condenses into droplets inside of the tubing.

The tubing can fill with water.

The water can flow down the tubing and into your mask.

This is condensation of the humidified air and is often known as “rainout.”

Solutions for CPAP rainout:

1. Move your CPAP machine

Move your CPAP machine to a lower level than your mask. Use gravity to your advantage so that the condensation does not flow to your mask.

If your CPAP is on a bedside table and the tubing drains down to your mask, try moving your machine onto a lower surface so the tubing and air flows up. If water droplets do form, they will flow back down to your humidifier and not into your mask.

2. Try wrapping your hose to keep the air warm

Wrapping the hose using specially designed tubing wrappers can help to insulate the blowing air from the lower temperature of the room, reducing “rainout.”
You can even run the tubing beneath your blankets to keep it warm.

3. Adjust the temperature in your bedroom

It’s the difference between the temperature in your bedroom and the temperature of the air in your tubing that causes the rainout. If your room is really cold at night, you’re more likely to see condensation in your tubing.

4. Adjust your humidifier settings

Talk to your equipment provider about changing your humidifier settings. If you live in a warm or very humid climate, you may not need a high temperature setting. The humidifier is trying to warm the air to around 80 degrees Fahrenheit.  

5. Use heated CPAP tubing

Heated tubing reduces rainout by keeping the temperature of the air constant as it travels from the humidifier to your mask. If the air stays warm, it doesn’t condense into droplets.

Heated tubing is designed to manage humidification in real-time based on changes in the climate in your bedroom, such as increases or decreases in temperature or humidity, and changes in your CPAP pressure and mask leak.

Check out ClimateLine heated tubing here (it is covered by most insurance-learn more about insurance coverage for supplies here).

Have you experienced CPAP rainout and think you may benefit from heated CPAP tubing?

Order ClimateLine Tubing


Other posts you may find interesting:


  1. Tim Birdwell Reply

    I have been experiencing rain out since I’ve started this treatment in December 2018. I have the heated tube, and use to keep everything on auto. Then I started using manual , but don’t know what settings to run it on. Still getting Rail out. My cpap does sit on my night stand, which is head level , but I have the tube ran over top of my head board and I still get rain out. Maybe I need to put it on the floor, keep the hose going up over head board, and put settings back on auto.

  2. Dave Reply

    I have had “rainout” at times with my cpap machine. The noise of the water in the tube has caused me to wake a few times. What found that has helped is that I cut up an old t-shirt and rapped the tube using paper medical tape about every 6 inches to insulate the tube. It’s free and only takes a couple of minutes, and beat paying $25+ for a cover.

  3. Laura Brunetti Reply

    Thank you Dave

  4. Phil Reply

    For the first year – great. Now no matter the setting I get drenched. Have new heated tube – 72 room temp- auto setting or manual at any temp – no luck. Added a tube cover. Nothing has worked. Machine below head level. Help!!!!!

    • Kathryn Albert Reply

      Hi Phil, I am having the same issue. i have used my CPAP for a couple of years with no issues and within the last 6 weeks I have experienced ‘rain out’. did you find a solution? I am open to anything that will help.

  5. Sierra Reply

    With the AC on, I got a lot of rainout from my BiPAP until a couple of weeks ago. The large amounts of water woke me up and even resulted in a gurgling noise from the hose which kept me up. I took the hose outside and gave it the ol’ “lasso” treatment (swinging it overhead to remove the water via centrifugal force- it’s a 6′ tube so only swing from the middle, doing half at a time unless you have the strength and speed to get the whole thing going at once. I don’t. ‍♀️) After I emptied the tube with my lasso skills, and gave the neighbors quite a show, I’m sure, I wrapped my hose with a couple of ace bandages I bought from the Dollar Tree and used tape to secure them along the way. The tape is only on the actual tubing in small parts on either end to keep them from slipping. So far so good! And much cheaper than expensive hoses and covers and easy to remove!

  6. Leonard Zamkoff Reply

    With a turned off Soclean connected to a resmed airsense 10, the water in the humidifier tank bubbles with each intake of breath. This didn’t happen when I had a philips CPAP. Is the water bubble normal? The Soclean is off, so should be contributing no air to the tank.

  7. Brenda Reply

    I have a SoClean and a Resmed Airsense 10 as well. The water bubble is not normal. It should be nice and quiet. (Other than you can hear each breath of air as with every CPAP) I’m not sure why it is doing that for you. I would just double check the thin black hose to make sure it is pushed on tight to the water chamber. I do remember that adding the Soclean machine I needed at different water reservoir lid that allows the thin black tubing to be attached to it. I would call Resmed if you can’t figure it out…there should be no bubbling noises at all.

  8. Jeremiah Reply

    I had at to fight for air! Woke up not just to bubbling as water splashes but felt hard drawing in air!. I looked it up found this. Hope o van fix it.

  9. Lori Reply

    I’ve been using a cpap machine for years and every winter i experience what ya’ll refer to as rain out. Because i don’t have the fancy cleaning machine i clean my tubing and mask while taking a shower – about 2-3 times per week. I want to try wrapping the tubes to prevent rain out, but I can’t imagine having to uncover then cover the tubing each time. Cleaning is very cumbersome already.

  10. Mary Reply

    I been having rainout, i have the rubing wrapped as instructed by Doctor, still have the same problem, i had cpap on headboard, moved it to night stand, then moved it to floor still have rainout, i dont know what to do. This has been going on over a month.

  11. Uma Reply

    For ResMed Apap machine what does 3 or 4 or 5 stands for humidification? I want to know how much percentage of humidity is 3 or 4 or 5

  12. James M Courtney Reply

    Seeing zero replies to any of the posts on this blog, makes me think there is no remedy coming from this blog, therefore useless, no help.

  13. Sakthivel Reply

    I have been using with heated tube for the past 8 months and it was working fine. Last night, I heard water bubbling in tube and had rain out. I heard the bubble sound even after turning of the machine. I also found water in the tube. Please help. I am unable to use the machine.

  14. Kenneth Reply

    I am having the same issues with a rainout and haven’t found a solution. However, I have for the bubbling noise issue. I have found that if I pull the (water container or whatever it’s called) completely from the machine and then put it back it solves my problem. This has worked every time it’s happened to me. Hope it helps y’all as well.

  15. Robert J Lima Reply

    Rainout is the single most frustrating problem at certain times of the year and room conditions. I’ve tried everything suggested with no consistent help. Isn’t it time the CPAP engineers get a handle on this and FIX this problem ?

  16. Eric Reply

    I have a Philips machine sitting just below head level with the heated tube running down towards the floor and back up to my nasal mask and still waking up to moisture build-up in my mask tickling my nose. I’ve got the tube temp set to max and now the humidifier set to 1 and will try just turning it off tonight. Is it possible that the source of the moisture may actually be from the air I’m exhaling from my nose?

  17. G.W. Reply

    I have been using a Phillips Respironics Dreamstation since March 2020. I have had a few Rainout issues that may have been self induced. I like to sleep in a cool room and as i live in an apt that faces the south, i have to deal with room temps fluctuating based on seasons and outer apts as i am in the middle of 3. To compensate i have a fan that sits in the hall but blows into the bedroom. I am also a side sleeper both left and right, with a full headgear Airfit F20 mask and standard non heated hose. My dreamstation is on a bedside table and the hose runs down between the table and bed then back up and over my shoulder to the mask. It was a cool night when i went to bed and woke up to a foggy morning outside, so i am thinking that perhaps my fan and the outside temp change may have contributed to this rainout. I am thinking about a hose hanger to help elevate the hose which should allow the condensation to flow back into the tank.

  18. Victoria Casias Watson Reply

    I am ready to stop using the CPAP. I have all the bells and whistles and still have “rainout” Help… This has been a journey since May 2020. Right now I am wrapping my tube with Ace bandages and hoping this will be the answer. I have little hope tho… My doctors says I have Severe Apnea. I am thinking I would be able stay asleep if I just don’t use this machine… Yikes.

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