You’re drifting off and the tube starts to gurgle, or you wake with water on your face. That’s rainout: humid air from the humidifier cools in the tube and condenses. It’s fixable.
Signs of rainout
The AASM lists (AASM PAP troubleshooting FAQ):
- popping or gurgling noises while the CPAP is running
- water droplets in the mask or CPAP tube
- water spraying in your face at night
Fixes, in order
| Step | Fix | Source |
|---|---|---|
| 1 | Use heated tubing if your machine supports it | AASM, ATS, ResMed |
| 2 | On ResMed AirSense 11 with ClimateLineAir 11: use Climate Control Auto, which “protects against rainout” | ResMed |
| 3 | In Manual mode: raise the tube temperature first | ResMed |
| 4 | If rainout continues and the air feels too warm: lower the humidity | ResMed, AASM, ATS |
| 5 | Warm your bedroom | ATS |
| 6 | Insulate the tube with a fleece or insulating cover, or lay it on your chest under the blanket | ATS, AASM |
| 7 | Dry a wet tube: run the CPAP with an empty water tank for a few minutes | AASM |
Sources: ResMed AirSense 11 user guide, AASM PAP troubleshooting FAQ, American Thoracic Society tip sheet.
AirSense 11 settings explained
From the ResMed AirSense 11 user guide:
- Climate Control Auto is the recommended default with ClimateLineAir 11 heated tubing and the HumidAir 11 tub. It sets the tube to 80°F (27°C) and aims for 85% relative humidity.
- Tube temperature can be set from 60 to 86°F (16 to 30°C), or off.
- Climate Control Manual lets you set temperature and humidity separately, but “rainout protection is not guaranteed”.
- Without heated tubing, the troubleshooting table says droplets on your nose or in the mask and tubing may mean the humidity is too high or the tube temperature is too low.
ResMed’s provider guide also suggests switching to ClimateLineAir tubing, and turning on Climate Control Auto, for patients with rainout (ResMed troubleshooting guide). ResMed’s US shop listed ClimateLineAir heated tubing for Air11 devices at $49 on 13 October 2026 (ResMed shop). Medicare covers heated tubing (A4604) once every 3 months as a PAP accessory (supplies schedule).
Don’t create a new problem
Turning humidity right down cures rainout but can bring back dry mouth or nasal congestion. Heated tubing is designed to let you keep the humidity up without condensation.
Also, empty the tub before you travel. ResMed warns against using the AirSense 11 with water in the tub while in transit, such as on a plane or in a vehicle, because water could spill into the device or be inhaled during turbulence (ResMed AirSense 11 user guide). See travel CPAP.
Verdict
Heated tubing is the real fix. On an AirSense 11, use ClimateLineAir tubing with Climate Control Auto. Without heated tubing, warm the room, insulate the tube, and lower the humidity a step. Run the machine dry for a few minutes to clear a wet tube.
Heated tubing details: ClimateLineAir heated tubing explained.