Cool-mist Humidifier Residue?

Updated on February 13, 2009
S.B. asks from Fullerton, CA
5 answers

I've been running a cool-mist humidifier in my 16-month-old son's room at night and naptime pretty much since he caught his first cold back in September. Every surface in his room is covered with this white, kind of powdery residue now and I have no idea if this is normal or if I'm doing something wrong. I only use filtered water in it, so I don't think I can blame it on contaminates in the water itself. I read on-line last night that I should be cleaning it daily with bleach. I've only been using dish-soap and in all honestly, I haven't been cleaning it daily (because the instructions for the machine said I didn't have to). If I use bleach, should I run some through the machine in an effort to clean it out completely? Is it just that I need to replace the filter (which I've washed, but never replaced before)? Thanks in advance for any suggestions.

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So What Happened?

After a bit more research and a lot of feedback from Deanna Leigh, I (we) discovered that this white residue is mineral deposits from the water. Apparently, there are demineralization filters available that I will be looking into. In the meantime, I cleaned the darn thing real good, changed the (regular) filter, and bought some distilled water. My son is coughing, too (croup) and I just hope I didn't cause it (or make it worse) with the machine! Thanks to everyone for your help!

More Answers



answers from Las Vegas on


Most likely you need to clean your humidifier and change your filter, especially if you are running it every day. There are many web sites that have different suggestions on cleaning your humidifier. Some use vinegar or hydrogen peroxide.

When I clean mine, I use 1/2 cup of bleach and then fill with water. Then I run it out on my patio for 20 minutes so all the parts get bleached. If you can't run it outside, tape up the opening. When it is done, I dump the bleach solution and run it again outside with clean water. This seems like a lot of work, so next time I might try one of the methods online! You might also want to check your instruction book, and see what it suggests. Best wishes, M.

1 mom found this helpful


answers from Los Angeles on

It is normal. It should say something in the manual that came with it.

Sorry - I forget the details of it, but recall reading about it in the manual when I got mine.




answers from Los Angeles on

We had this problem last year with an older "ultrasonic" humidifier -- very quiet, but left a white powdery residue everywhere (even in the disk slot of a CD player). My husband thinks that the problem would have been solved by using distilled water (as opposed to just filtered water, which was what we had used). In any case, after our son (then about 10 months old) started coughing without having a cold, and continued to cough for many days, I stopped using that particular humidifier and his coughing stopped. However, I never tried the distilled water idea. You may want to try that first.

We recently bought a new Vicks cold mist humidifier and a Vicks warm mist humidifier (wasn't sure which would work better). We have had no issues with any white powdery substance being deposited by either of these humidifiers.



answers from Los Angeles on


Glad you asked this question!! I have been through three humidifiers in the last year and have had the same issue with ALL of them.

Glad to see the advice about cleaning. Wondering if this still happens with non-filter type humidifiers?

At any rate, thank you!


answers from Las Vegas on

Do NOT use bleach!!! Bleach is not only environmentally unfriendly, it's also potentially toxic. One of the primary ingredients in bleach is sodium hypochlorite. When it's mixed with household cleaners containing ammonia, chlorine gas is formed. When chlorine gas is formed, it can be easily inhaled causing damage to the respiratory tract and even death. This is obviously not something you want for you and your family. Even if bleach isn't mixed with ammonia based cleaning products, the hypochlorite found in conventional bleach isn't healthy. At high doses, sodium hypochlorite can injure nerve and liver cells and some people have allergic reactions to this substance. How sure are you that this is being rinsed out of your humidifier. If you have tea tree oil - that is a wonderful and natural fungicide, anticeptic and will keep your humidifier running clean.


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