Machine and humidifier
CPAP Humidifier Not Working: Water Not Going Down or Not Heating
If the water level in your CPAP chamber barely changes, or you still wake up dry with the humidifier on, the humidity setting may be too low, the room may be humid, or the heater may have a fault. Check the settings and the chamber fit first. Fisher and Paykel say a heater plate that does not warm is a sign of an operational problem that your equipment provider should check.
Signs
- Water level in the chamber almost the same in the morning
- Dry nose, mouth or throat despite the humidifier
- Heater plate not warm after the machine has run
- Humidity setting appears off or unavailable
- Message about the humidifier or power supply
Common causes
- Low humidity setting or humidity off
- Water use depends on the humidity and temperature you set. If the setting is low or off, little water evaporates.
- Humid room or warm weather
- Fisher and Paykel note water use depends on the humidity in the room as well as your settings, so less water is used in humid weather.
- Chamber not seated
- If the chamber is not fully inserted it may not sit on the heater plate correctly.
- Power source that does not support humidification
- The DreamStation 2 manual says some battery or power supply setups do not support humidification and an 80 W power supply is required to support it.
- Heater fault
- If the water is not going down at all and the heater plate does not warm, the humidifier may not be operating properly.
Fixes to try, easiest first
Check that humidity is turned on
Open the comfort or My Options menu and confirm humidity is on and not at the lowest level. On machines with automatic climate control, make sure the heated tube and chamber are both attached, because some features only work with both.
Raise humidity one step
If you wake up dry, raise humidity one level and try it for a night or two. ResMed suggests moving one notch at a time.
Reseat the chamber
Remove the chamber, check it is not cracked, and reinsert it until it clicks into place.
Use the supplied power cord
If you see a message that the power supply does not support humidification, switch to the power supply that came with the machine, or use the device without humidification on a battery as the manual directs.
Fill with distilled water
Use distilled water if your manual calls for it. ResMed's AirSense 11 guide says to use distilled water only with the standard HumidAir 11 tub. Minerals from tap water can coat the chamber and heater surface over time.
Have the humidifier checked
If the heater plate never warms or the water never goes down, Fisher and Paykel advise having the humidifier checked by your equipment provider.
A humidifier that does not heat is an equipment repair for your provider. Talk to your doctor if dryness continues even with a working humidifier, or if you have nosebleeds, ongoing congestion or a sore throat, since mask leak, mouth breathing or medicines can be the real cause.
Supplies that can help
Distilled water is what most CPAP humidifier chambers are meant to be filled with, because it leaves little or no mineral scale behind.
The removable water tank of a CPAP humidifier; it wears and needs replacing, especially if it cracks, clouds or leaks.
Tubing with a built-in heating wire that keeps humidified air warm all the way to the mask, which is the main fix for rainout (water droplets …
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Mask types this applies to
Frequently asked questions
How much water should my CPAP humidifier use?
It varies with your settings, the room humidity, mask leak and how long you sleep. Philips says a full tank should last a typical night under most conditions. A change from your usual pattern matters more than any exact number.
Why is my humidifier water not going down?
Usually the humidity is set low, the room is humid, or the chamber is not seated. If none of those apply, the heater may not be working and should be checked.
Can I use my CPAP without the humidifier working?
Most machines can run therapy without humidification, and it is better to keep using CPAP than to skip nights. You may feel drier until the humidifier is fixed.
Sources
Last reviewed October 11, 2026. How we research · Report an error