The show centers on FBI special agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) who work on cases linked to the paranormal, called X-Files.

The episode was notable for its sheer amount of water and its lack of bright lighting, a stylistic approach that Gillian Anderson likened to filming in Vancouver.

In Goodland, Florida, during a fierce hurricane, Sara Shipley and her son, Evan, desperately try to flip the washing machine but fail to do so as tentacles ensnare them.

Elsewhere at the Breakers Condominiums, Deputy Greer encounters the creature after finding a dead man covered in a slimy substance on a toilet.

He encounters Dougie, a looter, Walter Suarez whose girlfriend Angela Villareal is nine months pregnant, and George Vincent, an anti-government gun rights activist.

Dougie steals the deputy's wedding ring and knocks over a container of Epsom salts into the tub where the unconscious Greer is soaking after Scully removed several specimens from his neck wounds.

Scully tells Walter Suarez to aim for the sprinklers, realizing that the freshwater kept the creature at bay, as with the deputy until Epsom salt was added to the water.

Amann was originally tasked with bringing back the character of Arthur Dales, and his first story revolved around a monster lurking in an abandoned gold mine.

Frank Spotnitz, the show's executive producer, was not drawn to the mine aspect, but he enjoyed the concept of a monster running amok in an enclosed space.

Originally, the sea monster was blown onto dry land and crawled into the building before Amann decided to re-write it as living water.

[4] The monster itself was created by special effects makeup supervisor John Vulich, a task he considered "the single most difficult thing [he] did all season".

[5] Aguamala is also the slang name for the Portuguese Man o' War, a venomous jellyfish similar in form to the episode's primary antagonist.

[8] McGavin was also slated to appear in the Duchovny-penned episode "The Unnatural", but two days into production, he suffered a stroke, forcing the producers to remove his scenes and replace them with another "Arthur Dales", played by M. Emmet Walsh.

)[10] During filming, costume designer Christine Peters was required to bring six dry replicas of each character's wardrobe to prevent pneumonia.

Production designer Corey Kaplan received the script for "Agua Mala" around Christmas and, realizing the amount of work, immediately began drawing up plans for the set.

Michael Liedtke and George Avalos, in a review of the sixth season in The Charlotte Observer, called the episode "just plain bad".

[16] VanDerWerff criticized Darren McGavin's appearance in the episode, calling it a "glorified cameo", and noted that his character functions as the "kind of old man who stands on his porch and yells about the good old days to the neighborhood kids.

Tom Kessenich, in his book Examination: An Unauthorized Look at Seasons 6–9 of the X-Files gave the episode a mixed review, writing "as far as [Monsters of the Weeks] go, 'Agua Mala' was pretty standard fare.

"[20] "Agua Mala" earned an ASC Award by the American Society of Cinematographers for Outstanding Achievement in Cinematography – Regular Series.