# Is my old humidifier dangerous?

**URL:** <https://boards.straightdope.com/t/is-my-old-humidifier-dangerous/427669>\
**Category:** Factual Questions\
**Created:** [November 25, 2007, 5:00am UTC](https://boards.straightdope.com/t/is-my-old-humidifier-dangerous/427669 "2007-11-25T05:00:51Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Mosier](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Mosier](https://boards.straightdope.com/u/Mosier)\
**Post date:** [November 25, 2007, 5:00am UTC](https://boards.straightdope.com/t/is-my-old-humidifier-dangerous/427669/1 "2007-11-25T05:00:51Z")

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There’s stuff growing in it, because I stored it without getting all the water out first. I cleaned it out as much as I could, but I’d like to know whether it will blow noxious fungal spores around my house when I turn it on.

It works by converting small amounts of the water to steam, and blowing the steam out of a small nozzle at the top. Would this process kill any bugs that might have survived the scrubbing? It wasn’t possible to actually reach every part of the water reservoir while I was cleaning it, because its a large flat tub with a tiny hole at the top to insert the steam maker motor. I couldn’t fit my hand inside.

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**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\
**Post date:** [November 25, 2007, 5:18pm UTC](https://boards.straightdope.com/t/is-my-old-humidifier-dangerous/427669/2 "2007-11-25T17:18:47Z")

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Are there any instructions with it that say you should NOT run bleach water through it?

If not, I would suggest putting a little bleach in the water in the reservoir and then letting it run outside or in the garage for a bit until it is empty. Then do it again with clean (non-bleached) water to get the bleach out.

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [November 25, 2007, 5:38pm UTC](https://boards.straightdope.com/t/is-my-old-humidifier-dangerous/427669/3 "2007-11-25T17:38:33Z")

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[QUOTE=ZipperJJ]  
I would suggest putting a little bleach in the water in the reservoir and then letting it run…  
[/QUOTE]  
Many of those old humidifiers worked by running 120 volts between a couple of big carbon electrodes immersed in the reservoir. If you add ions to the water, such as bleach (sodium hypochlorite), the electrodes will pass a larger current. That can damage the electrodes.  
Soak the reservoir with some bleach, and even put the electrodes in there, but _don’t plug the unit in_.  
Rinse it out after an hour or two, and fill with clean water.  
Then plug it in.