Drinking the H2O in South America is unavoidable. If you´re going to get bowel draining amoebas-and you can bet on it-then make it worthwhile. Find the nearest coastal town that sports at least running water, and order the largest fruit batido (smoothie) they have. Nothing gives you more pleasure in saying, "ooh my stomach" than a South American batido. At least this way the diahrea was worth it.