When making puerh at home, I use <gasp!> filtered tap water through my fridge. I actually love it as it seems to have a happy balance between filtration and mineralization.
A couple of times, however, I've been asked by friends or family to put on informal "tea tastings" at different locations. For this, I didn't want to use tap water, so I purchased large bottles of water. I was shocked that there was a notable change of the flavors of the tea (and not for the better). I used high quality water too -- Fiji, on the first occasion, SmartWater for the second.
If any of you purchase (or have purchased) bottled water for tea, what brands do you prefer?