When someone needs to create chaos in a building or just get everyone to leave, they trip the sprinkler system. Just apply a lighter flame, or perhaps a bullet, to one fire sprinkler, and all of the sprinklers on that floor—or even in the entire building—will suddenly kick off. Everyone gets drenched, and there's a mass exodus from the building. Sometimes, pulling the fire alarm will activate the sprinklers as well.
In the real world, only some sprinkler systems work like this—usually in buildings with a very high fire risk. While some neighboring sprinklers could go off due to the water hammer effect, most modern systems use sprinkler heads that have their own individual trigger (usually a glass tube that breaks when it gets too hot, or in older systems a lead slug that melts at a low temperature), thus limiting the water delivery only to the location of the fire. There are two simple reasons: 1) Where cisterns are used, the amount of water available to put out the fire is limited, so naturally you want as much of that water as possible to go where it will do the best job putting out the fire before the cistern runs dry and 2) Spraying water on things tends to damage them, so you only want to do that where it's truly necessary. Where sprinklers are connected directly to the main water supply, if they all went off simultaneously there wouldn't be enough pressure for the system to work adequately without much larger and more expensive pipes throughout the entire building. Additionally, activating the fire alarm system (via a pull station or smoke/heat detector) will not trip a sprinkler system, although sprinkler systems can trip a fire alarm system if they are interconnected with each other (and they usually are). Fire suppression systems that flood an area with high-expansion foam (such as found in aircraft hangars) or inert gases are normally activated this way, but this is because these systems will not only extinguish the fire but also kill everyone in the room, so for safety reasons are supposed to be manually activated after confirming that everyone is out.
This trope is so prevalent in the media that people now expect sprinklers to go off all at once. Businesses are reluctant to install sprinkler systems because they think even the smallest fire will cause enormous water damage. This trope may also have been responsible for a lot of real-life criminals drenching their—and only their—jail cell.
Also, while sprinklers in media spray little bits of clear water, a real sprinkler system—which typically sits for years without use and which is designed to put out or stop the spread of fires as fast as possible—dumps between twenty and one hundred gallons (80-400 liters) of filthy, stagnant water per sprinkler per minute—assuming they work at allnote . Not exactly the best way to spend your day. Compare that to a simple shower, which puts out about one-and-a-half to two gallons (six to eight liters) per minute.
- Touma utilizes this trope in the second episode of A Certain Magical Index. His opponent has magical wards set up all over his apartment building, and he needs to destroy them to make the man beatable. Setting off the Telepathic Sprinklers (which cause the ink on the wards to run, making them powerless) disables all of the wards at once without him needing to track them all down.
- Marvel Disk Wars: The Avengers: When fighting Brother Blood and his vampires in a museum, Blade uses a single lighter to trigger all the sprinkler systems, which he filled with holy water beforehand.
- In a Gaston Lagaffe strip, in order to remind his coworkers of the dangers of smoking (back when it was acceptable to smoke indoors), he deliberately rewired the office's sprinkler system so that it would go off directly above the smoker's head, and not the whole floor.
- In another strip, he rearranges the sprinklers to fire continuously for five minutes every day—he's growing rainforest plants, and is trying to recreate the climate.
- In The Incredibles, Bob gets a message that self-destructs, causing a small fire for a brief second that sets off all the sprinklers in the house, getting groans from the rest of his family. Cut to them drying books and furniture to avoid permanent water damage. It works because of the Rule of Funny. Oddly, those same sprinklers don't go off when Jack-Jack discovers his power to burst into flame.
- In Meet the Robinsons, Lewis' invention at the science fair, after being tampered with, sets off a chain of events that makes... a scale representation of Vesuvius explode, setting off all the sprinklers in the gym.
- In the dodgeball scene in Chicken Little, the title character is flung against a window and slides down, catching himself on the fire alarm pull station which activates and sets off the sprinklers in the gym.
- In The SpongeBob SquarePants Movie, a wisp of smoke from a short in an electrical outlet is enough to trigger all the sprinklers at a souvenir shop, reviving all the dried sea animals there, including SpongeBob and Patrick, who then have their revenge on the shop owner.
- Averted in Aliens, Ripley holds a lighter to a sprinkler in the med-lab to attract the attention of the Marines in the control room, and it doesn't activate any of the sprinklers outside that room.
- Done in The Matrix, shortly after the famous lobby scene. Neo's elevator firebomb somehow manages to set off every sprinkler in the building, drenching the Agents (several stories above the blast) at a dramatically opportune moment. Somehow the dinky sprinklers in the room also manage to fill the place up with what looks like about a foot of standing water, just to make the upcoming helicopter/machine gun scene look that much more awesome.
- In Casino Royale (2006), Bond is chasing a bomber through Miami International Airport when the bomber changes into a TSA uniform and turns a "sprinkler activation" key on an alarm panel, drenching the terminal.
- Just starting a regular fire alarm would have worked exactly the same way and there was no reason at all to drench the whole place in water. It just looks more interesting than dry people leaving the building in an orderly fashion.
- Possibly justified in-universe by 007's sense of humour.
- In the movie Constantine, the title character does this, after having his assistant bless the water. Enter *bleep*-off smoking demon hordes.
- In Bruce Almighty, Bruce uses the power of God to stop a party by activating the house's sprinkler system. Justified in that the sprinklers are being set off by willful divine intervention, not a fire.
- In Mean Girls the headmaster stops a riot by setting off a single fire alarm and drenching everyone. This was particularly effective as 'everyone' was teenage girls who were worried about their hair. However, the sprinklers appeared to only come on in the corridor, not the rest of the school.
- In Frequency, Dennis Quaid's character does this to not attract attention to himself, when he escapes his interrogation room after electrocuting the villain who has framed him for murders he didn't commit.
- In the movie Accepted during the big party scene, one of The Rival school members pulls the fire alarm. For some reason instead of releasing a siren and alerting the fire department (possibly because the place was actually a condemned mental asylum they had given a Makeover Montage), all this does is turn on the sprinkler systems and causes everyone to start dancing in the rain.
Wet T-shirt party!
- In Hackers, the entire sprinkler system is computer-controlled and can be set to 'test' at a certain time.
- In Veronica Mars, Veronica breaks up a fight by holding a lighter to one sprinkler head.
- An odd example in Kindergarten Cop where the fire alarm goes off, O'Hara checks the door and sees smoke slowly filling the empty hall, but no sprinklers. Cut to a moment later where kids screaming as they run towards the exits, all the sprinklers are going off, and the lights are showering sparks all over the place.
- In The Body (2012), a fire somewhere in the hospital kicks off all sprinklers in the building.
- Played straight near the end of Middle School: The Worst Years of My Life, when Rafe sets off the sprinkler system, modified with bright fabric dyes. The fire alarm part is averted a bit, as a more realistic modern fire alarm sound is used instead of a bell (as what's typically used in the media, though bells are rarely used as fire alarms in America nowadays.)
- In Who's That Girl, Nikki Finn accidentally sets off the sprinkler system in an apartment building when she and Louden Trott hide out in a utility closet and she moves the flame of a lit cigarette lighter near one of the sprinklers.
- The Dresden Files:
- Averted in the novel Small Favor. Harry sets off most, if not all, of the sprinklers in a building by sending the heat from a fire spell to each individual sprinkler using Sympathetic Magic—since they're all of the same design, by heating one directly he can heat them all simultaneously. And it's mentioned that the stagnant water stinks.
- Played straight in one of the short stories, when Harry needs to interrupt a wedding before The Big Damn Kiss, but is pinned down by hotel security in the hallway outside the ballroom. He uses a weak blast of fire aimed at the sprinkler directly above him, and succeeds in setting off the others.
- Happens when a character in Joan Hess's A Conventional Corpse sets off the fire alarm at a college, and the sprinkler system goes off on every single floor of the building. Particularly conspicuous, as colleges would be the last place to want Telepathic Sprinklers even if they did exist, due to student-prank false alarms.
- A variation is discussed in Sergey Lukyanenko's Competitors. While locked in a room aboard a Space Station, Leonid suggests starting a fire, assuming the automated system will open the door. Lena calmly tells him that the automated system will isolate the room and suck out the air to suffocate the flame.
- The "stagnant water" part is specifically mentioned in Artemis Fowl, when Holly shoots a hole in the sprinkler's tank to avoid the averted Convection Schmonvection of a magma flare.
- Completely averted in Raising Dragons. When Billy sees Adam trying to trip the school bathroom's sprinkler system with a lighter, tries to stop him, and accidentally sets it off with his breath, the water is described as "putrid smelling" and later "sticky and smelly". There is also no mention of any other sprinklers going off—only the fire alarm clears the building.
- Averted in Polar Star, by Martin Cruz Smith. Arkady Renko is Locked in a Freezer on a Soviet factory ship by the villains. He tries to trip the alarms by lighting some oily rags near the heat sensor, but nothing happens.
- Amber "Cutthroat *bleep*" Volakis attempts this by blowing smoke from a cigarette on a sprinkler, in an attempt to drench Dr. Cuddy with the intention of getting her thong. It doesn't work. So she uses the lighter directly, and sure enough the sprinklers in the entire sector go off.
- And again, in episode 6.12 ("Moving the Chains"), when the mystery prankster sets off a fire alarm in House and Wilson's apartment, causing every sprinkler in the place to let loose.
- And in episode 4.2 ("The Right Stuff") not so much a telepathic but more a hesitant sprinkler. Using the defibrillator in a hyperbaric chamber causes a small fire. The fire alarm is instantly triggered, and the staff quickly puts the fire out. It is not until 10 seconds later that the sprinkler kicks in, apparently for no other reason than the Rule of Funny.
- In Law & Order: Criminal Intent episode 2.6 ("Malignant") one half of a pharmacy had suffered water damage due to the sprinklers going off. The other half did not get wet because the pharmacist had disconnected that half of the system. The otherwise savvy detective Goran does not comment that this was unnecessary.
- Crane, in the episode "Liar Liar", set off a sprinkler to interrupt a romantic moment between two people. Justified, since he was in the same room, behind a screen. Watching him emerge, soaking wet, a triumphant smile on his face? One of the funniest moments in the show. This instance seemed to only apply to the apartment itself, as the hallway didn't show water spraying.
- There was another episode where he tried to empty out a theater by setting off the sprinklers. All he accomplishes is giving himself a shower, because only the one sprinkler is set off.
- However in the episode where the brothers open a restaurant, a Cherries Jubilee explosion at a customer's table caused all the sprinklers to go off, even the ones in the kitchen.
- In one Halloween episode of Roseanne, she sets off the sprinklers at the lodge with a lighter as her big Halloween prank. She stands on a chair with an umbrella as the rest of the party goers are soaked.
- The second season finale of Community featured Troy rigging all of the sprinklers in the library to spray paint instead of water, which all go off at once when Shirley pulls the fire alarm.
- Averted in Due South, when Frasier and Vecchio are trapped in a bank vault. Frasier trips the sprinkler in order to flood the vault, and that sprinkler is the only one to go off in the whole bank.
- The New Avengers: In "Complex", Purdey is trapped inside a building which is attempting to kill her. Steed and Gambit dump a bunch of matches and lighters to her through the mail chute. She uses these to trigger the sprinklers which go off through the entire building and short out the computer controlling the building.
- There was a music video, can't remember the song, where a bunch of partiers tripped the nightclub's sprinklers. Almost an aversion, since multiple people are tripping multiple sprinklers, but they were having way too much fun dancing under water that should be highly pressurized, filthy, and probably ice-cold.
- Averted in the filming of X Japan's PV Jade, when Yoshiki managed to set the bed on fire during a sex scene involving fire. The sprinklers in the old abandoned theater being used were filled with sewagefilled water. The scene never made it out of the cutting room.
- In No More Heroes a mook holds a torch up to a sprinkler, causing all the sprinklers in the hallway to go off. Travis's
lightsaberbeam katana isn't waterproof, so in results in a comedic electrocution, and a short detour to turn off the sprinklers.
- The 'massive flood of sprinklers' variant is subverted in Grim Fandango, when the protagonist tries to flood a vault this way to escape. It just results in a puddle and a subtle, but very useful, clue.
- The player has to make use of this in Space Quest II: Vohaul's Revenge, with the classic 'wastebasket full of paper' method.
- A similar puzzle in Penumbra Black Plague involves this, requiring igniting a barrel laced with gasoline to trigger an emergency release on a door. Requiem takes this Up to Eleven, where aside from all the sprinklers going off like the previous example, a water pipe bursts and slowly floods the room even after the sprinklers have stopped.
- Averted in The Sims 2 (and probably the other two, but I can't speak for those). Chances are, you're only going to have one sprinkler in the house to begin with, in the kitchen, where there's more danger of fire; but if you do have more than one (likely by the fireplace or the grill if it's covered), only the one in a position to put out the fire goes off. And really annoying in the college expansion when that *bleep* cow decides to be funny and set it off.
- The fire suppression system FTL: Faster Than Light lets you install on spaceships is an aversion; it goes off only in rooms that are on fire.
- The Last Days of FOXHOUND:
- Decoy Octopus blows cigarette smoke at the hospital room sprinklers and sets all of them off, much to the chagrin of the injured Mantis and Ocelot.
- And this:
Sniper Wolf: [with a partially unzipped jacket] Oooh Mantiiiis!
Psycho Mantis: [looks to the left] Eeh?
[Next Panel. Sprinklers are going off.]
Liquid Snake: Oh great. that's just what I need.
- In an early arc of El Goonish Shive, Tedd and Elliot attempt to invoke this to stop the Goo Monster. Although, interestingly, their plan doesn't actually require this trope to succeed, it fails nevertheless: the school had skimped on repairs in order to pay for more murals.
- Averted on the Teen Titans episode "Fear Itself", which has Robin trip the sprinkler system inside the video store to destroy Control Freak's sentient minions. He uses batarangs to do it, and he sets off every single one of them.
- The Simpsons played this straight in "A Test Before Trying." To buy Bart more time to study for a vitally important test, Bart recommends Principal Skinner pull the fire alarm. As Skinner ponders this, the Good Angel, Bad Angel trope comes into play, but the "devil" is his mother Agnes, whom claims "You wimp!" and activates the pull station, setting off the alarm (which is basically the same as the school bell) and all the sprinklers in the hallway, as the faculty and teachers evacuate through the showers.
- Bounty Hamster. In "Save the Whale", Cassie and Marion have to disarm a bomb in the cold storage area of a Space Whale. She lights a fire to melt the block of ice sealing the bomb, only for the sprinklers to go off, then get frozen by the liquid nitrogen jets, trapping them both in separate cages of ice.