I give tap water to my cats because in our area the water quality is good and I also drink the same tap water. If the tap water's quality would decrease at any moment in time I would not hesitate to buy bottled water because I then would be drinking bottled water myself.
I think the quality of water is the most important issue here and not the fact whether it comes from a tap or not. I do not have problems with people giving bottled water to their pets because it is only natural to give what is best to your pet.
The only issue I have with bottled water is that when you use bottled water you should make sure it comes from a re-usable bottle. Plastic bottles are known not to decade very fast in nature and are cluttering our oceans. Subsequently the oceans are full of plastic and animals living in the ocean get sick or die because of eating plastic.
