We use bottled water, just to be safe. You can buy 2 1/2 gallon "off brand" jugs at Big Lots for just a $1. Also there are sams club and wal-mart brands. I think it's worth the money just to be safe. And, it's easy very convenient to keep near the tank.
Unless labeled "spring water", all bottled water IS tap water, exactly the same as you get from your kitchen tap. http://www.nrdc.org/water/drinking/bw/bwinx.asp Considering they get most of their water when you give them baths anyhow, this just seems like an enormous money drain. None of mine have anything wrong with them from being bathed and misted with tap water.
I didn't know that it was the same as tap water. I guess I'm more concerned with chemicals/buildup that could be present in our pipes, as we have a rather old house. We just have the one, so a $1 bottle probably goes a while, I could see it being expensive if you have several.
It looks like the "bottled water'" that site is refering to is more like the "spring waters." The bottled water I am talking about is purified drinking water... it is purified usually by reverse osmosis. Not chemicals. My tap water is city water and it has a lot of chlorine and other chemicals in it. When I had a frog, we had to buy the purified water for him.