distilled water vs tap water?

Good God! Push up your glasses, pull up your high waters, but please leave this discussion if your life is that tied to debating over and over again what causes Legionnaire's, etc, blah-blah-blah.
My experience...
No problems with secondary infx in an immuno-competent patient (me) after 6 years of mainly using tap and Artesian water... I was too lazy to get the distilled/DI (essentially the same) water.
BUT, big scale build-up over time. Also, too lazy to wash the humidifier chamber weekly and empty it daily, so that probably contributed. Scale was hard to clean; even with vinegar or Lime-away (tried it once).
BUT, now have new machine. I get Distilled water at any grocery store/Target/Wal-Mart/etc. Easier to clean now. And now I won't have any concerns about any infections at all... even if some blog you can and can't get from water.
Only pack in suitcase if absolutely necessary... Why hassle with that?! Airport security, wet bags, extra weight, etc... all because you didn't want to stop at WalMart when you left the airport? Its probably on the way to the American Legion. Use tap water, clean the thing when you get back.
Also, definitely dry humidifier chamber out whenever traveling!!! Your insurance will NOT pay for a new one if you screw that one up.

In Arizona the water is very hard and the hardness can vary throughout the year.

I have a culligan whole house water softener (using salt pellets) I may try switching to tap water and seeing how it goes.