Using CPAP
Do You Have to Use Distilled Water in a CPAP Humidifier?
Most CPAP manufacturers recommend distilled water in the humidifier. We explain why, what alternatives your manual might allow when travelling or during shortages, and the common mistakes that can damage your machine.
Why distilled water is recommended
Tap water contains minerals such as calcium and magnesium. When the humidifier heats water, those minerals stay behind and form white scale in the chamber. Over time scale is hard to clean, can damage the chamber, and may affect how well the humidifier works. Distilled water has had most minerals removed, so it leaves little residue.
Tap water can also contain microorganisms and other substances. Distilled water reduces these concerns.
If distilled water is not available
Check your manual, since recommendations differ between machines and countries. Some manufacturers allow other water types when distilled is not available, for short periods. If you use tap or bottled water temporarily, empty and clean the chamber daily and return to distilled water as soon as you can. If you live in an area with unsafe tap water, do not use it in your humidifier.
What never to put in the chamber
- Essential oils, fragrances or scented products
- Cleaning products or bleach
- Anything other than water
These can damage the machine and may irritate your airway.
Cleaning off mineral scale
If you see white crusty deposits in the chamber, your water has been leaving minerals behind. Many manufacturers suggest soaking the chamber in a diluted white vinegar solution and rinsing thoroughly, but follow the ratio and method in your own manual. Chambers that stay cloudy or scaled after cleaning, or that have cracks, should be replaced, typically on a 6-month schedule.
Daily water habits
Empty leftover water each morning and let the chamber air dry. Fill with fresh water at night, up to the max line only. Do not top up yesterday's water, which can let residue and germs build up.
Frequently asked questions
Can I use boiled tap water in my CPAP?
Boiling kills many germs but does not remove minerals. Some manuals allow it as a temporary option. Check yours and clean the chamber more often.
Is bottled water OK for CPAP?
Bottled spring or mineral water still contains minerals. Some manufacturers allow it short term. Distilled water remains the usual recommendation.
Can I run CPAP without water?
Many machines can run with the humidifier off or the chamber empty, depending on the model. Check your manual; running the heater with an empty chamber may not be recommended on some devices.
Sources
This page is general information, not a diagnosis or medical advice. Read our medical disclaimer.