I'm using still water (cheap one) for them but someone recommend me to buy revers osmosis filter and use it for them as not all chemicals are get out from water during the time ...
As well you can find some drops for tap water treatment they are good for frogs/rept. I did not try it as I do not like chemicals but they work ?!? I think filter is the best plus you can drink this water and it will be much better even for you Flickr: Traveler Toad's Photostream