# Disinfecting a Humidifier - question

**URL:** <https://boards.straightdope.com/t/disinfecting-a-humidifier-question/488964>\
**Category:** Factual Questions\
**Created:** [March 10, 2009, 3:29pm UTC](https://boards.straightdope.com/t/disinfecting-a-humidifier-question/488964 "2009-03-10T15:29:51Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![salinqmind](https://avatars.discourse-cdn.com/v4/letter/s/3ec8ea/32.png) [@salinqmind](https://boards.straightdope.com/u/salinqmind)\
**Post date:** [March 10, 2009, 3:29pm UTC](https://boards.straightdope.com/t/disinfecting-a-humidifier-question/488964/1 "2009-03-10T15:29:51Z")

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when cleaning this thing, would it be all right to use hydrogen peroxide? Or should I stick with bleach to kill mold and bacteria.

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**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\
**Post date:** [March 10, 2009, 3:59pm UTC](https://boards.straightdope.com/t/disinfecting-a-humidifier-question/488964/2 "2009-03-10T15:59:30Z")

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Bleach is what my humidifier recommends. Based on a lab I did in Microbiology last week, Hydrogen peroxide would probably work, but it needs to sit for 60 minutes to kill _staphylococcus aureus_, where bleach only needs, IIRC, 2 minutes.

If you want a really good disinfectant that will kill spores as well as bacteria, mix some white vinegar with your bleach water. “Combine 5 ounces of household bleach with one gallon of water and add 8 ounces of 5% distilled white cooking vinegar to the diluted bleach solution.” - [http://ehs.uky.edu/biosafety/disinfectants.html](http://ehs.uky.edu/biosafety/disinfectants.html)

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**Author:** ![Baracus](https://avatars.discourse-cdn.com/v4/letter/b/2bfe46/32.png) [@Baracus](https://boards.straightdope.com/u/Baracus)\
**Post date:** [March 10, 2009, 5:01pm UTC](https://boards.straightdope.com/t/disinfecting-a-humidifier-question/488964/3 "2009-03-10T17:01:31Z")

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I would stick with bleach. It doesn’t take much to be effective and it is relatively cheap. If you are going to use **WhyNot’s** “pH-adjusted” bleach, please do the mixing in a well-ventilated area. If you are not in a rush, leaving the reservoir or whatever to soak in plain diluted bleach for an hour or two will be just as effective.

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**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\
**Post date:** [March 10, 2009, 5:21pm UTC](https://boards.straightdope.com/t/disinfecting-a-humidifier-question/488964/4 "2009-03-10T17:21:51Z")

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> [@Baracus](#):
>
> If you are going to use **WhyNot’s** “pH-adjusted” bleach, please do the mixing in a well-ventilated area.

Can I ask why? I mean, why it would need to be more well-ventilated than using bleach alone? I’m not trying to argue, just trying to figure out what I’m missing. Might be useful for my lab report, y’know.

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**Author:** ![Baracus](https://avatars.discourse-cdn.com/v4/letter/b/2bfe46/32.png) [@Baracus](https://boards.straightdope.com/u/Baracus)\
**Post date:** [March 10, 2009, 6:39pm UTC](https://boards.straightdope.com/t/disinfecting-a-humidifier-question/488964/5 "2009-03-10T18:39:47Z")

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> [@WhyNot](#):
>
> Can I ask why? I mean, why it would need to be more well-ventilated than using bleach alone? I’m not trying to argue, just trying to figure out what I’m missing. Might be useful for my lab report, y’know.

Mixing acid with bleach will release chlorine gas. I looked into it a little bit more and none of the sites recommending using the mixture specifically warn about that possibility, so maybe only a small amount will be released at those dilutions. At the very least you would buy yourself a little insurance in case you screwed something up and forgot to add the water first, used too much bleach, etc.

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**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\
**Post date:** [March 10, 2009, 9:25pm UTC](https://boards.straightdope.com/t/disinfecting-a-humidifier-question/488964/6 "2009-03-10T21:25:09Z")

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Thanks!

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**Author:** ![salinqmind](https://avatars.discourse-cdn.com/v4/letter/s/3ec8ea/32.png) [@salinqmind](https://boards.straightdope.com/u/salinqmind)\
**Post date:** [March 10, 2009, 11:18pm UTC](https://boards.straightdope.com/t/disinfecting-a-humidifier-question/488964/7 "2009-03-10T23:18:50Z")

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Thanks for the information.