Growing up I drank tap water back home in America, as did everyone else I know. Later on bottled water became more popular, but as a kid the only time I remember not drinking tap water was when our hometown was hit by a hurricane and we didn't have electricity or safe running water for weeks. I am sure the tap water back home is still safe, but it seems like everyone prefers bottled these days.
In China I drink tap water if it has been boiled. It is safe but there is a lot of mineral residue left when the water boils off. My husband doesn't even like to drink the bottled water from our water machine if the water has not heated all the way up to boiling first, as apparently you can't always trust that the water is always actually bottled water and not just tap water packaged up to look like bottled water.
Personally I take my chances because there are times when I would just rather not drink hot water, or wait for my hot water to cool off.