“Water-borne pathogen.” Three gut-twisting words with enough power to make any epidemiologist, public health official, or globetrotting tourist double over. One of the most common forms of disease transmission is the microbial hijacking of our most precious fluid. This mechanism of infection is employed by a motley crew of microscopic organisms that have adapted to prey upon our unquenchable thirst, from pervasive bacteria like cholera and typhoid to often less famous but no less formidable parasites such as giardia and dracunculiasis.