Don't drink the water

[alcidesdiver]

This may sound dumb, but:

I'm going on my first trip to Coz in a week, and I know not to drink the water, but what happens when you are diving in it? Surely some will get into your mouth. Is the drinking water from the same source as the water we dive in?

I m not sure (No offense) if I understand the question; just because there is a general belief that mexican water is "polluted" or "dirty" does it mean that the ocean water also gets "polluted" in the mexican boundaries?. Maybe in the area of the US or Canada, or any other country, is safer, but when it gets to the limits of the country it gets magically polluted? Gee. Now I feel dumb myself.
Sorry if I am bugging anybody with this reply...it is not my intention.