Personally, I think we have all gotten a little spoiled by this trend of bottled water over the past couple of decades. I grew up on NYC tap water and have continued to drink it whenever I'm home (I also admit to being spoiled and use bottled water for the convenience and also to stay hydrated). I have used unfiltered tap water with all of my little sneaky ones for as long as I've had snakes and none of them have ever had any illnesses or adverse affects that have appeared to be related to the quality of NYC tap water. The only time I misted with Poland Spring bottle water was when sometimes spraying the expectant eggs from one of Lilly's recent clutches when they were somewhat dryer than they ought to be, a phenomenon that has been corrected by the use of sphagnum peat moss inside a container with fewer and smaller holes in it. Ozzy, who is just about 14 months old and almost 200 grams at 2.5' didn't even have THAT luxury as HIS egg was misted with tap water, since I didn't even THINK of that when he was incubating and he appears to be THRIVING!
In any case, this is only my solitary and somewhat humble opinion.
Just sayin'.