i was in mexico for a month, had tap water, had some excellent spring water, but one time my friend brought some water from another spring and for nearly a week i couldnt eat anything without immediately liquid shitting afterward. fasting + some enzyme pills an american woman had worked, + patience. my two friends drank the water with no problem though so i would say just make sure your digestive system is strong before you go. i´ve always had a weak system + when i eat anything that i know triggers stomach pain, it gets worse for a while.