|Original Airdate:||February 21, 1999|
|Written by:||David Amann|
|Directed by:||Rob Bowman|
Stranded in the middle of a hurricane in Florida, Mulder and Scully seek shelter in an apartment building, not knowing that a tentacled monster is terrorizing the residents.
Arriving there in Florida during a hurricane, Agents Fox Mulder and Dana Scully arrive at the home of retired FBI agent Arthur Dales, the first to look into the X-Files. He tells them about the Shipley family and how Sara Shipley called him in a panic after her husband was attacked by something in the bathroom with tentacles. Scully is dubious about this but believes that something has indeed happened to the Shipley family during this hurricane.
Mulder and Scully go to the Shipley house and find the bathroom door barricaded shut, no sign of any people, and a cat hiding in the washing machine. They have a brief run-in with Deputy Greer who believes they are burglars until Mulder disarms the man and shows their FBI ID.
They attempt to go to the airport but are trapped by the hurricane. Elsewhere at the Breakers Condominiums, Deputy Greer encounters the creature after finding a dead man covered in a slimy substance on a toilet.Looking for a place to escape the storm, they find the deputy’s vehicle parked outside the Condominiums. Searching the place they discover Greer on the ground with his neck covered with red welts. Scully tries to get medical attention for the man but the storm has cut everyone off. Mulder goes around the complex to find the rest of the people and warn them that the thing is in the plumbing. He encounters Dougie, who is looting the condos, Walter Suarez whose girlfriend Angela Villareal is nine months pregnant. Mulder brings them all back to the landlord’s apartment, where the deputy is, but he learns of one more tenant, George Vincent.
Arriving at the anti-government gun nut’s condo, Mulder attempts to get the man to come out and join them for his own protection. Mr. Vincent refuses but the attack by a creature in his apartment forces him outside.
Mulder hypothesizes that this entity attacking them was driven here from the bottom of the sea by the hurricane. It was driven into the city’s water system and is now attacking people.
Dougie the looter steals the deputy’s wedding ring and knocks over a container of Epsom salts into the tub where the unconscious Greer is soaking in water (his fever was killing him so they put him in the tub with ice) after Scully’s removal of some creatures from his neck wounds. While Angela Villareal relieves herself, she spots the creature in the tub with the deputy.They enter the bathroom and find the clothes of the deputy but the man gone. Mulder theorizes that the entity doesn’t just live in water but IS water. Becoming visible only when it attacks. He believes that the thing uses these people as hosts to reproduce, their bodies water content being used to feed the growth of new creatures. He understands they need to leave but Scully says they don’t have the room in their car.
Mulder suggests they use the deputy’s Prowler but then notices the looter, Dougie, has disappeared. Charging outside, he finds the vehicle missing along with the looter.
Mulder gets attacked by the creature in the hall. When he returns with the welts all over his throat, George Vincent slams the door and takes them all hostage, leaving Mulder to die in the hallway. Angela goes into labor and Scully finds herself forced to deliver a baby.
Water accumulates in the light fixture above them and the creature appears. It grabs George Vincent by the neck and Walter Suarez saves the man with a well placed gunshot. Scully told Walter to aim for the sprinklers, having realized that the freshwater kept the creature at bay (like with the deputy until Epsom salt was added to the water).Mulder and Scully reminisce with Arthur Dales about the case. Dales is impressed that Scully figured out how to save Mulder’s life, delivered a baby, and did both at gunpoint. He suggests that he wouldn’t have retired if he’d had someone watching his back like that at the bureau.
- The title of this episode is Spanish for "bad water." The same Spanish phrase is also used as a slang term for the Portugese Man o' War, which is a particularly venomous species of jellyfish that can be found in the Caribbean.
- In early drafts of this episode's script, the monster is not a sea monster but one that is loose in an abandoned cave with a gold mine inside it.
- Evan Shipley is wearing a Miami Dolphins #13 Dan Marino jersey, but with the name "Shipley" displayed in capital letters on the back.
- A poster for the film The Great Escape can be seen in George Vincent's living room.
- In the scene that shows Mulder arriving at the door of George Vincent's apartment after hearing gunfire (29:37), there is clearly no magazine in Mulder's pistol.
- When Mulder and Scully enter the Shipley's house, they are both carrying large flashlights. Then on their way to the basement, Mulder is suddenly carrying a small flashlight and Scully is still carrying a large one. In the next scene, Scully is then suddenly carrying a small flashlight also.
Car 54: When Deputy Greer calls in before entering the apartment building, he identifies himself as car 54. This is probably a reference to the 1961-1963 TV series Car 54, Where Are You?, a police comedy that starred Joe E. Ross as Officer Gunther Toody, Fred Gwynne as Officer Francis Muldoon and Al Lewis as Officer Leo Schnauser (Gwynne and Lewis were reunited as Grandpa and Herman Munster in the 1964-1966 series The Munsters). An unsuccessful movie based on the series was released in 1994.
- Jeremy Roberts as George Vincent
- Joel McKinnon Miller as Deputy Greer
- Diana-Maria Riva as Angela Villareal
- Valente Rodriguez as Walter Suarez
- Silas Weir Mitchell as Dougie
- Nichole Pelerine as Sara Shipley
- Max Kasch as Evan Shipley
- Darren McGavin as Arthur Dales
- Allen Cutler as Road Block Deputy