Demineralized Water and CPAP

by Andre
(Los Angeles)

I am Bordeaux France and distilled water is hard to come by. Is it ok to use demineralized water?

Some say it is unsafe due to possible bacteria and that it may come from non portable sources. Is that true? Demineralized water is cheaper and easier to come by here.


Dear Andre,

The CPAP manual or the therapist says to use distilled water in the humidifier as it is free of minerals. This will prolong the life of the humidifier and prevent mineral buildup on the inside of the chamber making it appear dirty.

Demineralized water is the water that has been stripped of its minerals in every method that exists today. So, one method is distillation, and other known methods are:

  • electro dialysis,

  • deionization,

  • membrane filtration.

I repeat, demineralized water is the term for the water without minerals, and distilled water is the water stripped of its minerals through the distillation method - when the water has been boiled off and recollected from steam.

Bottom line...there is no big difference between a distilled water and demineralized water, at least not it the finished product.

You can try the demineralized water for your CPAP humidifier, and if you don't have it now, you can use tap water (don't use tap water more that once a week). If you use tap water often, you will see a hard crud film on the bottom of your CPAP humidifier.

If you do get mineral buildup in the humidifier chamber you should be able to clean it with a white vinegar and water solution to dissolve the minerals.

A much better method that tap water (if you can't find distilled or demineralized water) is to filter the water and boil it. The filter would remove most of the minerals and chlorine and some other particles, and boiling would take care of the microbial concerns. This method is not perfect as the distillation process, which makes the water truly pure, but it might work pretty well.

And the last advice for you - whether you use tap or distilled water - is to dump your CPAP humidifier water every morning. Bacteria can build up in humidifiers if the water is not dumped frequently.

I hope it helps. Don't be afraid to comment back.

Remy Thierry
Founder of Sleep Apnea Guide

Comments for Demineralized Water and CPAP

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Dec 24, 2011
demineralized water
by: trw99

do not boil the water more than once as heavy metals accumulation and is not boil off

at a guess one cc of vinegar should be OK to leave in a humidifier while in use. and would seek guidance to increase this

May 09, 2016
What I have discovered about C-PAP waters
by: Spanky

I have found tap water gives me headaches, evev used one night. The water from walmart , Etc. has bleach residue from the sterilazation of te jug. I have also found that the clear plastic bottels are more apt to not have the bleach as it makes the product bottel foggy. Furthermore, i dont want mineral deposits in my lungs, or bleach. And distilled water is not for normal drinking as it will flush the needed nutrients from your body and give you a worn down feeling.
Ive only been doing this 10 years and have never had build up in my machine. Hope this helps someone.
P.S. the deminuralized water they like to add calcium to and thats in no way good for your lungs.
Live , Love , Learn and Share knowledge.

Nov 03, 2016
by: jodie

So is it OK to use demineralized water then I was using disteld water in my cpap machine and my mum said to get the water from the super market or bunnings I saw two letter bottles of demineralized water and I wasn't shoure if it was OK to use I'm still quite not shoure wether its OK to youse in my cpap machine

Nov 06, 2016
Demineralised Water
by: Adrian

Jodie - I was using demineralised water, (Coles brand), until I discovered this in fine print on the back... "Not recommended for consumption, not suitable for therapeutic devices". If it's not recommended for consumption, I am pretty sure I don't want it in my lungs. I might try distilled water instead.

Feb 06, 2017
How long to boil water for cpap machine
by: Anonymous

How long do you have to boil the water to make it safe to use in the CPAP machine? 2 minutes?

May 06, 2017
Distilled water DIY
by: Anonymous

I purchased a distiller for 150.00 that comes with a carbon filter on the discharge. So far so good and no more hauling gallons from the store.

May 28, 2017
Thank you for your advice
by: Paul Strecker

I'm new to the CPAP machine with the humidifier built in it. I didn't know whether I could use Aquafina water in my capo. Know that I know the difference I'll stick to the distilled water. I read your article further found where you said to empty it every morning that helped to Thank you Sincerely Paul Strecker

Jul 21, 2018
CPAP water
by: Michael

I cannot find distilled water in London(UK) but I have been using Purified Water from my local chemist in Hampstead. It seem to work. They do not keep large stocks so order ahead. Boots says the can order it on demand.

Jul 21, 2018
by: Adrian

Hi all.
I have changed to using water straight out of the Puratap. For those not familiar, it is a separate kitchen tap that has 2 filters. One filters out particles and the other filters out chems. bacteria, etc. I figure the 2-stage filter is about as clean as I can get.

Cheers - AC

May 10, 2019
by: Tnlizzie

I have been using deineralised waterin my humidifier attached to my cpap for ages without any repercussions but after finding that it shouldn't be used I was considering using filtered rain water from my tank.
Would this be advisable.

Nov 04, 2019
Same problem
by: Anonymous

I'm also trying to find a cheaper way to refill my CPAP machine. In the US distilled water runs about a dollar a gallon(3.75 lts), but am now living in Australia and it costs me $6.95 for a 4 liter jug from the chemist.

My question is, does anyone know if it would be ok to filter tap water through a Sawyer Mini Water Filtration system and use it for my CPAP? I'm thinking of purchasing one. Thanks in advance to anyone who replies.

Dec 04, 2019
Filtered water
by: Barbarajean

I use a pur filter pitcher by filling it with
tap water. Saves money from buying gallons of distilled water.

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