Earlier quoted context omitted.
The slag issue can be solved by using demineralized water, and reverse osmosis water filter, which remove almost all minerals, can be had for pretty cheap these days.
People say "pretty cheap", but a lot of reverse-osmosis filters I've seen are ~$150 to $450. Also consider: it takes ~4 gallons of water to make 1-gallon of reverse-osmosis water. All water-purification methods have their own issues. ------- If you plan to make distilled water (aka: boil water to remove impurities)... that's basically what a warm-mist boiling-type humidifier does _anyway_. All good water-purification…
https://www.theperfectwater.com/home-master-hydroperfection-...
I personally think an evaporative humidifier is the way to go, as long as you are okay with the evaporator getting gross over time.