MG -

Not a good generalization. In many places in the US you have to ask for water, and I've run into places that charged the same for a glass of water as for a glass of cola.

A few small "home-style" eating places in SE Kansas don't bother to serve water automatically, because the local water is so bad that it gags and sickens people not accustomed to it. They generally don't charge for it if you ask for a glass of the local stuff to chew on. They may or may not serve bottled water - in limited amounts - without charging. Even the ones that give you a free glass of something drinkable may demand payment if you want a second glass.

John