I have people look at me funny when i just drink straight from the tap. Some people don't think tap water is clean or something.
I guess many people are not aware that a lot of the bottled water is just tap water filled into bottles and sold for a fairly high price. I carry Nalgene bottles filled with tap water in my backpack.
A few kilometers from my home there is a bottling plant. Their water is - to some people - much tastier than our tap water. That is kind of surprising as it is the same water.
Apart from that tap water has more and stricter regulations to follow than bottled water. So it could be expected to be at least as clean if not cleaner than bottled water.