Travel websites told me almost every city in the United States, big and small, has potable water coming out of the tap, whereas basically every city outside the United States, big and small, does not have potable water coming out of the tap. Is this true? If so, why is this?

Here's my data so far:

* Canada seems to have potable tap water at the same rate as the US.

* Indonesia does not have potable tap water.

* Mexico does not have potable tap water.

* India does not have potable tap water.