one note of interest, when we were in Ensenada, we asked our tour guide, who has lived in both US and Mexico about the water/ice thing.
he told us that he had been born in Ensenada, and to this day, if HE drank the water, he could get sick, but that all the nicer restarants/bars used treated water and ice.
We did have Marguaritas at the jewelry and leather stores, of course they pass them out to get you "happy" so you will buy more, and we never had problems.
Ate a restaurant, even raw oysters and shrimp, drank drinks over ice there too, and no problems.
Just our experience.