O.K. to mist with distilled water?

[lonewolf1253]

I need to mist my Boa's glass enclosure about three times daily to keep up the humidity and, "of course" this is leaving hard mineral deposits on the glass. Pain in the behind, since to remove it, I have to detach every thing and scrap with a razor blade and then scrub with white vinegar. I've read on many sites that distilled or reverse osmosis water is bad for the snake as it has no minerals and the snake does lick droplets of it off the glass. But really, I can't see where that could present a big problem as I frequently see her drinking tap water from her large dish. I really would like to mist with reverse osmosis water. I'm tired of these mineral deposits staining the glass. So my question is, Is it safe to mist with mineral free water, while providing tap water in the main drinking dish? I think it would be but I was just wondering what other, more experienced, keepers think of this? Thanks!
BTW I tried switching to natural spring water and its leaving even heavier deposits, so who knows what's in that stuff. My reptile source sells reverse osmosis water for 30 cents a gallon. I'd love to switch to that, especially when she's old enough to go into the 90 gallon tank I've purchased in advance.