Using Bleach in a Humidifier?

October 22, 2009

A bottle of bleach.Is it harmful to add bleach to the water in your humidifier?

By kim from Leominster, MA



October 22, 20090 found this helpful
Best Answer

Bleach is an irritant. The fumes are unpleasant and can pose a health hazard. Undiluted, bleach is corrosive and will damage many surfaces such as skin and fabrics. So I would not do it.


Bronze Post Medal for All Time! 213 Posts
October 22, 20090 found this helpful
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Don't run the humidifier with any bleach in it (it's VERY bad for your lungs to breath it!) but do clean your humidifier once a week with bleach-water (to kill mold spores)! Vinegar can also be used to clean it.

* If you'd like to add something to your humidifier, you can add one drop of tea-tree oil (only occasionally) or if you have a cold or flu you can add a drop or 2 of eucalyptus or mint oil or a teaspoon of the old fashioned Amber colored Listerine (it has eucalyptus and menthol in it), but don't use the blue mint or citrus Listerine because they have a sweetener added which can encourage mold growth.


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October 24, 20090 found this helpful
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It's harmful to breathe in bleach under any circumstance!


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October 26, 20090 found this helpful
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The Wal-mart in our area sells an additive to keep the water in a humidifier clean from mold and bacteria. It is fairly inexpensive. One bottle usually lasts awhile. I believe the manufacturer is Holmes.


A humidifier should be disinfected every 4-6 weeks or when needed. I use a mix of bleach and water, rinsing thoroughly before using.

January 23, 20170 found this helpful
Best Answer

Bleach will attack rubber parts of your humidifier, like seals and gaskets. It's OK to use a mild bleach solution for disinfecting while you clean, but you don't want to expose the parts to it long-term.


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October 22, 20090 found this helpful

I think so. What is it you are trying to accomplish?

If your problem is mold, either see how much you can clean with a soap and bleach solution and do it weekly, or find out of there is something else to do by finding the 800 consumer satisfaction number for the brand and talk to them.


Chlorine is poisonous to people and animals and very irritating to the breathing passages. Now how much bleach you meant I don't know but I wouldn't go blasting it into your room.

October 22, 20090 found this helpful

Thanks ya'll, that answered my questions.


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October 22, 20090 found this helpful


February 29, 20160 found this helpful

only if you want to destroy the cilia and delicate mucosa lining your airways

December 31, 20171 found this helpful

Public pool, what do you smell? A lot of bleach, right?

February 14, 20181 found this helpful

recently heard that teatree oil is harmful to pets

March 28, 20180 found this helpful

Humidifiers should be clean at minimum every 3 days.

December 8, 20204 found this helpful

No, it's not harmful to add bleach to humidifier water, if you use a sensible proportion. You should add enough to control microorganisms, and no more. This can be done by being conservative with how much you add to each tank, and then observing whether mold grows on the filter, and adding more bleach as necessary. In this way, you will learn how much you need to add.


I have been using bleach in my humidifiers for years, with no issues at all. No, you cannot smell bleach in the air in my home. No, we do not go around coughing or bleeding from the mouth. If you are breathing in something that is damaging your lungs or mucosal membranes, you're going to be aware of it!

The real risk is in allowing mold to be spread throughout your home via untreated humidifier water, where everyone breathes it in all day. But people love just throwing out an uninformed "NO!" just because it's easy to pretend that's the correct and safe answer. It is not.

In reality, if you actually look at product labels and Safety Data Sheets for bleach products, you will see that the only inhalation danger is irritation from prolonged breathing of concentrated vapors.


You'd have to stick your nose in the bottle of bleach and leave it there. The Safety Data Sheets don't even list LC50 values for inhalation.

See what I did there? I referenced actual data to make my point. Look at it for yourself.

The other thing people recommend is a tiny bit of tea tree oil or something else, which is absolutely useless.

There are a lot of "bacteriostatic" humidifier additives sold. These products should never be used. Read the label on those products--they really are inhalation hazards. And they don't even control the real threat, which is mold, not bacteria.

Why isn't bleach commonly recommended for this use? Because bleach is very inexpensive. It's for the same reason they'd rather sell you $8 mouthwash which does nothing, rather than telling you to rinse your mouth with ultra-cheap hydrogen peroxide.

December 8, 20200 found this helpful

Some humidifiers--like mine--have no rubber parts, or any parts which would be damaged by bleach.

December 8, 20200 found this helpful

You could clean them every 3 hours, but that wouldn't stop the real problem, which is mold growth on the filters--which then gets transferred into room air.

February 4, 20220 found this helpful

Adding oils to a humidifier is NOT good advice. The oils contribute to growth of mold. My daughter found this out the hard way.

February 13, 20222 found this helpful

Last year the inside area around the ultrasonic transducer of my humidifier began becoming colored pink from pink mold, I sterilized it per instructions, but after a few days the mold was back. This year I tried adding vinegar to the water and in a few days noticed grey or black mold. Sterilized it again and this time found that adding just 1/4 ounce of 5% laundry bleach per gallon of water has prevented either of the molds from developing.


My humidifier has a two-gallon tank, so I use 1/2 ounce of bleach for each refill. At that level I do not notice any odor from the bleach.

July 2, 20231 found this helpful

Thank you very much for a common sense, fact based answer.

I remember from emergency prep/water storage that bleach is one common option to help keep water viable. I also remember how much chlorine I drink whenever I swim in pools.

I had also read the information on the bacteriostatic water additives for humidifiers including a couple of the SDS's after which I said to heck with that! I'll take bleach any day.

RE: "See what I did there? I referenced actual data to make my point."
I just loved that comment! LOL!!!

By chance are you able to make a starting point recommendation for my 4 and 5 gallon humidifiers? I would like to cut short the trial period if I may. I started out with 1 drop (8.25%) per 2.5 gallons, and now I am at 2. I had searched this question before and came up with nothing but "NO" along with ignorant alternatives. This is the first detailed common sense answer I have seen, which is just ridiculous.

I got here by searching for "How many drops of bleach can I add to my humidifiers?" I have three 4-gallon humidifiers. 2 ultrasonics and 1 evap. Still trying to decide whether to jettison the evap - or - jettison an ultrasonic and get another evap. Maintenance is the deciding factor. I had no clue that evap filters are a constricted market. You cannot find ultra-cheap prices for an ultra cheap product. Thank you government! Nooooot!

Evaps last longer between cleanings and mine is easy to clean, but the filter is problematic. I generally prefer the ultrasonic as it takes up less space and is less obtrusive, but it must be cleaned more often and only a few pieces go in the dishwasher.

Again, thanks for your great comment!

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