[jcims]

They ‘cheat’ a little by lofting liquid water which then evaporates. We have a water softener and the cool mist humidifier left a smoke-like particulate floating in the air (i think it was either salt from the softener or minerals from the water)

[mfkp]

Yes, that's the minerals in the water. Using distilled water prevents this.

[TeMPOraL]

I discovered this when doing a post-assembly indoor test of a Luftdaten air quality sensor I built[0]. I kept it running for few hours and then looked at the data, and saw some ridiculously high levels of PM2.5 and PM5 in the evening. I've decided to investigate it. Over the next two days, I figured out that the increased levels happen at times when our air humidifier is running, which led me to discover that those ultrasonic air humidifiers essentially atomize everything that was mixed with/dissolved in the water - and we were using filtered tap water with ours. With distilled water in the humidifier, the sensor did not show increased particulate levels.

We've mostly stopped using the humidifier now, because I can't find a source of distilled water that doesn't involve buying plastic bottles.

--

[0] - https://luftdaten.info/en/home-en/

[mfkp]

I've encountered the same issue (high plastic bottle waste along with high cost). Short of boiling your own water outdoors to avoid polluting the indoor air, it's challenging to find a source for bulk distilled water.

[oska]

Rain is essentially distilled water (evaporation from terrestrial water bodies and then condensation in the atmosphere). It picks up some contaminants in the atmosphere and some dissolved gases when it condenses but it's going to be mostly free of minerals (i.e. not be hard). So collecting rain water is one source of bulk 'distilled water'.

[bitxbitxbitcoin]

Depending on where he lives, that might actually be illegal to do.[1]

[1] https://bestlifeonline.com/illegal-collect-rainwater/

[im3w1l]

Boiling your water indoors will humidify the air.

[mfkp]

Yes, and it will also release the impurities/minerals into the air, which is what we're trying to avoid by using distilled/boiled water.

I live in an area with very hard water (around 300ppm), and the evaporated minerals are very visible in the air (and it leaves a white residue on the surrounding area).

[OJFord]

> I live in an area with very hard water (around 300ppm)

Tangential, but being curious how hard that was relative to mine led me to discover that Thames Water (i.e. only useful to anyone reading in London) has a pretty good page at [0] - a summary on the site itself but the PDF is really worth a look, lots of numbers. Maybe it's a regulatory requirement, but I wouldn't have expected it to be so easy to get so much information from them about my specific (it serves many districts in and around London with different sources and equipment) water supply.

[0]: https://www.thameswater.co.uk/help-and-advice/water-quality/...

[IndrekR]

Boiling water will not get much of the minerals into the air. This is why distillation works.

[Cthulhu_]

Would filtering it first help with that?

[jcims]

We also have a air purifier that watches for particulate and they would battle each other constantly lol.

Moved to an evaporative humidifier, my air quality appliances now operate in peace.

[devtul]

Oooooh, so that is the cause of my apartment being hazy?! Just moved to a new place, air humidity can get around 10% and since I don't enjoy being tazed by my sofa I bought a small humidifier from Amazon, both I and my wife noticed what seems to be a cloud in our living room.

[jcims]

If it's a cool-mist type humidifier, definitely.

I grabbed an evaporative one from the local big box hardware store and zero 'smoke'. You should get some bacteriostat and you'll have to replace the paper elements every now and again, but it's way better.