Preventing humidification rainout/condensation FAQs | ResMed
Preventing rainout/condensation
Healthcare professionals > Support > Humidifiers > Preventing rainout/condensation

FAQs: What is the best way to prevent humidifier rainout/condensation?

Humidification adds moisture to the air that your patient breathes and can make CPAP, APAP or bilevel therapy more comfortable. But some people experience difficulties with humidification condensation, also known as 'rainout'. Find the answers to frequently asked questions about humidifier rainout here.

My patients say that they can't use their humidifiers sometimes because the hose fills up with water. Why does this happen? What can I do about it? 

This water is condensation and is often called rainout. If your patient's room is cold, the warmed, humidified air cools down when it comes into contact with the colder air in the room. When the air cools, the amount of humidity (water vapour) that it can hold is reduced, and this causes the humidity to 'rain out'.

There are several ways to deal with this situation:

  • Use ResMed’s Climate Control system with the ClimateLine or ClimateLineAir heated tube. It prevents rainout by maintaining constant temperature and humidity levels.
  • Turn the humidity level down.
  • Ask your patient to raise the bedroom’s temperature at night to reduce the difference between the room temperature and temperature of the humidified air. The patient should also cover the tube with a ResMed Tubing Wrap to keep the tube, and the air travelling through it, warm.

I've heard that wrapping the hose with fabric will help with rainout. Is this true?

Yes. Wrapping the hose can help to insulate the treatment air from the lower temperature of the room, which helps to reduce rainout. The ResMed Tubing Wrap provides warmth and greater comfort while increasing the amount of humidity at the mask by up to 20%.