I'm just doing a pole to find out the majority vote I myself use spring water for everything. Yes it's a small fortune but I feel it's worth it just was wondering what everyone else does?
RO with a double carbon filter. A good RO system is a solid investment if you plan on keeping chams. You can get them online and have them set up the way you want them or get standard systems at the home improvement stores.
Our tap water is good and contains no fluoride, but I run it through a Brita filtered pitcher, since I have it anyway. When he is outside, I use hose water because I think my water is fine.
I use tap water. I haven't done full research on its chemical composition, but I know Yorkshire water has a lot of Calcium Carbonate (hard water area) Some occasional crust on my Veiled girls nose, this seems to come and go at random. I blame the fairies but it doesn't concern me one bit
Also, some water residue on the leaves and chams - this makes them look a little duller from time to time. They are not particularly vain lizards though, so I don't care 'bout that neither.
I myself use distilled, only because that's what goes into my foggers. Tap water will ruin a fogger. They just drink the water droplets that accumulate from the fog as it spills into the cage. I think this is another one of those things where there is no "right answer" it just depends on your situation for the most part