A quick follow-up note. You'll remember we were getting excessive dust on our furniture while using a "cool mist" humidifier? That problem is gone.
The new evaporative humidifier has solved the problem while using regular, hard tap water. In design it is basically a small "swamp cooler." The water evaporates and leaves the mineral content behind inside the machine.
If I remember, I'll do another follow-up when we clean the machine for the first time. It is, by the way, a chore which I am not anticipating with pleasure.