This came up yesterday as a friend of mine who is considering a trip down to SP asked if the water was ok to drink. I explained that we have never had a problem as they use rain and well water and I can brush my teeth, drink some water from time to time but I prefer the bottled water as it is colder and tastes better. This led onto a discussion about Mexico and its reputation of Montezuma's revenge to vacationers. I have visited Mexico many times and also never gotten sick as I eat in restaurants, drink drinks with ice in it, and brushed my teeth.
My question is what is it that makes visitors to Mexico (or other countries not trying to give Mex a bad rap) sick? Is it the water, an area that can not use rain water or bad beer/tequila or a combo of all of them?