"Agua Mala" is the thirteenth episode of the sixth season of the science fiction television series The X-Files. It premiered on the Fox network on February 21, 1999 in the United States. The episode was written by David Amann, and directed by Rob Bowman. The episode is a "Monster-of-the-Week" story, unconnected to the series' wider mythology. "Agua Mala" earned a Nielsen household rating of 10.1, being watched by 16.9 million people in its initial broadcast.