Water Source Tampering

"Somebody's poisoned the water hole!"

Construction Worker: That nutjob Sweet Tooth is gonna poison the water supply!
Pizza Girl: This is even worse than when The Joker poisoned the water supply!
Construction Worker: Or when Scarecrow poisoned the water supply!
Pizza Girl: Or when Killer Croc poisoned the water supply! That's how he died, the poor fool.

— Holy Musical B@man!

Fear of drinking water is a classic paranoia, especially since in medieval times or earlier it could be quite difficult to come by a clean water supply (just imagine what it was like in the days before water filtration and the only river within miles had thousands of people throwing all their waste, including biological wastes, into it upstream) and thus a well could be the center of life for miles around. If anything happened to it or anyone tried to contaminate it, you'd never know until it was too late...

As such, super-villains or government conspiracies putting horrible stuff in the water has been the fodder of fictional plots for years. In other settings, the paranoia is not justified but might still be relevant to the plot. In stories set in modern, developed countries, this trope often employs some Artistic License. The sheer quantity of fluid in most water infrastructures would dilute most added contaminants to virtually nothing, not to mention the various micro-organisms that would absorb the initial damage in many cases, or the security measures water facility equipment has to prevent exactly this kind of tampering. Realistically, achieving this intentionally would require jumping a lot of logistical hurdles (unless one believes in homeopathy, at any rate).

Compare Tampering with Food and Drink, which is at least normally intended as a (deadly) prank. Can be a Poison and Cure Gambit. See also Cool, Clear Water for when a body of water is assumed to be clean based on how it looks, even though it's more realistic for it to be just as tainted and unsafe to drink as this trope.

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Examples:

Anime & Manga

• In Birdy the Mighty, this was Seichiro Hikawa's plan for the people of Tokyo, to turn them into "retro soldiers" by tainting the city's water supply with serum. See here, starting at 4:27.
• Invoked Trope in Cowboy Bebop: Knockin' on Heaven's Door. Vincent Volaju leaves a fake bomb in the water treatment plant to distract the authorities while actually planning to disperse the virus by other means.
• Ninja Scroll. A village well is poisoned to make it appear a plague is sweeping through the area — everyone flees leaving the bad guys free to carry out their plans without witnesses.
• In Rurouni Kenshin, Hannya forces Megumi to come with him by threatening to pour a vial of mercury into Kamiya Dojo's well.
• In Snow White with the Red Hair, Shidan manages to do this unintentionally by secretly raising beautiful glowing flowers in a cave that housed a spring in Lyrias. The flowers cause the water to become poisonous.

Comic Books

• Arne Anka: One strip, which revolved around Arne finding out he's got chlamydia, ends with him threatening to urinate in Stockholm's water supply, his friend Krille discovers his diagnosis and laughs at him for it.
• Batman:
  • A frequent plot of the Joker is to slip Joker venom into Gotham's water supply.
  • In his first appearance, Poisonous Person Dr. Phosphorus attempts to poison Gotham's water supply by submerging his toxic body in the city's reservoir.
  • Deconstructed in one comic when Bruce deduces Narcosis, the Villain of the Week, won't put his hallucinogen into the water supply because it's too easy to shut off. Instead, he plots to put it in the milk supply.
  • The plot of Batman/Punisher sees Frank Castle and Jean-Paul Valley fighting to stop Jigsaw from using an experimental rocket fuel from destroying two reservoirs and the water supply in Gotham and forcing the city into paying Jigsaw's newly acquired construction company to pay for a new one.
• Often used as a plot point in the Blueberry comics: one or more characters finally come across a water source after a long trip through the desert... only to find out that the bad guys (or at any rate, someone who does not want to see them come out of the desert alive) have poisoned it by throwing in a dead animal, usually a horse.
• A Captain America arc, during Cap's "The Captain" phase, has Madam Hydra/Viper putting drugs into Washington D.C.'s water supply that turn everyone who drinks the water into half-human, half-snake hybrids.
• During the Apocalypse War arc prologue of Judge Dredd, Block Mania, Orlok introduces the Block Mania to the city via the water supply.
• The Moon Kings, a criminal gang fought by the title character in volume one of Moon Knight, plan to extort Chicago by contaminating its water tables with a psychotic/hallucinatory drug. It's noted in-story that Chicagoans actually like and trust their water supply, unlike New Yorkers.
• Supreme Power is all too happy to show how terrifying this would be in the spinoff in which Nighthawk deals with an Omnicidal Maniac who has developed an always lethal poison and is trying to kill off a major city with it. It gets deconstructed when Nighthawk points out to the man that the water reclamation plant doesn't connect directly to the reservoir and there are safeguards in place to shut it off automatically if it's contaminated.
• The Ultimates (2002): The Chitauri have been dumping gamma butyrolactone to dampen people's thoughts, and they had been doing it for some time already.
• Wonder Woman (1942): A possible future shows the hero doing this when the inmates of a fortified prison manage to take the president hostage. As everyone in this future has taken/is on the age-regressing immortality drug L-3 she dumps an anti-L-3 agent into the water supply for the prison, causing all of the troublemakers to rapidly age up physically to their actual geriatric ages.

Fan Works

• A Cure for Love: Kira's ultimate scheme is to release a Sterility Plague into the water supply so that he may gain absolute control over the human race.
• Power Rangers Mythos features a variation of this, as the villain Avanth sets up a series of nodes on Earth that essentially "poisons" the Morphing Grid, the source of power for the various teams of Power Rangers. As a result, part of the plot will focus on the last available Rangers seeking out the nodes to destroy them and restore the Grid to full 'health'.
• Touhou Ibunshu: In the past of the setting, Yukari killed Yuyuko's parents by tossing a dead fairy in the waterhole.
• your move, instigator (draw your weapon and hold your tongue): Team 14 is sent to test out one of Orochimaru's poisons on a river and document the results. After seeing recently shorn livestock among the animals that have died and fallen into the water, the kids realize that this was the real purpose of their mission.

Films — Animation

• Kirikou and the Sorceress: Evil sorceress Karaba made sure the African village's main water source went dry. Kirikou decides to look it up closely and finds out a creature has been drinking it all for a while (the creature's belly has grown gigantic from all the water). He then borrows a red iron to pop it like a balloon, restoring the village's water supply, but at the cost of himself nearly drowning.
• In Old Master Q & San T (Shan T Lao Fu Zi, 1983), the Evil Plan of the antagonists begins with the mooks adding laxatives in the various water sources in Mr. Chiu's theme park.
• In Toy Story, one of Woody's quotes that play when someone pulls his string is "Somebody's poisoned the waterhole!"

Films — Live-Action

• Batman Begins has a variation. Scarecrow laces Gotham's water supply with his fear toxin for months, without anyone realizing it. The toxin has no effect in this form. It needs to be absorbed through the lungs to have an effect — the bad guys' ultimate plan is to use a microwave emitter to vaporize Gotham's water supply, thereby exposing the whole city.
• The Soviet tank crew in The Beast of War is shown emptying poison canisters into a well while attacking a village. Later on, one of the mujahadeen is killed when he drinks from a poisoned well. The Soviets' poisoning of every water source they come across ends up biting them in the butt later — a Soviet helicopter crew unknowingly drinks from a pond the tank crew had poured cyanide into earlier, and all die before they can radio assistance for the stranded tank.
• In The Challenge (1970 TV movie), a Combat by Champion takes place on a Pacific island. The US combatant poisons all the water sources on the island except one in the hope of ambushing his opponent there.
• The Charge at Feather River: Thunder Hawk's braves dump some of the bodies of the dead soldiers down the fort well following the massacre. This prevents the Guardhouse Brigade from being able to refill their canteens when they return to the fort.
• An inverted version is mentioned in Contagion (2011). The US government wants to know if they can distribute the cure this way but is told that it would only dilute it beyond practical effectiveness.
• In The Crazies (2010), the culprit turns out to be a bio-weapon aboard a plane that crashed into the marshes near the town, which are used for drinking and watering crops. When the protagonist finds out about this, he demands that the mayor shut down the water supply, only for the mayor to refuse, claiming that it would devastate the town (given that it's planting season).
• Dr. Strangelove's General Jack D. Ripper had a paranoid belief that there was a Communist conspiracy involving water fluoridation which will lead to contamination of everyone's "precious bodily fluids."
• In Erin Brockovich, PG&E tries to cover up the fact that they were poisoning the groundwater of the town of Hinkley, California with hexavalent chromium, which resulted in most of the town suffering from illness and cancer.
• Flesh+Blood (1985): During the siege of the castle where Martin and his mercenaries have taken refuge, the besiegers kill a plague-infected dog and hurl pieces of its corpse over the walls. Steven, who had been captured by the mercenaries, later throws some of the infected meat into the castle’s well during his escape.
• In The Men Who Stare at Goats, Bill puts LSD in the water supply of a military camp, sending the whole camp on a trip.
• Pirates of the Caribbean: At World's End: Elizabeth and Barbosa stop on a tropical island to replenish their ship's water supply, only to find a corpse had been deliberately dumped in the spring by one of the other pirate lords. Barbosa takes a taste of it and announces that the water's been fouled and is no longer fit to drink.
• The plot of the old action flick Never Too Young to Die involves the hero trying to stop a bad guy played by Gene Simmons from poisoning the water supply with a substance called Ram-K.
• In Nightmare at Noon, a mad scientist contaminates a town's water supply with a substance that turns people's blood green and turns them into mindless killers.
• In Rurouni Kenshin, Kanryu's men flush Megumi out of hiding by pouring rat poison into the village well. She is able to treat everybody who drank the tainted water, but she decides to stop hiding and return to Kanryu's mansion, fearing more attacks on the people.
• Signs: Bo, the little girl, would start glasses of water then find something wrong with them (such as "It has [her brother's] amoebas in it!") and stop drinking them, leaving them scattered all over the house, half-full. It turned out leaving the glasses all over was Bo being precognitive but unwilling or unable to explain it. Water was harmful to the hostile aliens, one of which had gotten into the house, and when they needed to be able to hurt it, it found itself standing in a room surrounded by partially full water glasses.
• They Cloned Tyrone: The investigation into Fontaine’s cloning leads the group to discover that the conspirators are putting mind altering substances into products - namely fried chicken, hair products, and “grape drink” for communions - widely used by their community.
• In The Tuxedo, Dietrich Banning (Ritchie Coster) is the owner of a bottled water company. By infecting a swarm of water strider insects with a strain of bacteria that causes water to dehydrate rather than rehydrate the drinker and letting them loose, he plans to render all the water in the world undrinkable except his own, thus increasing its value.
  • Although you'd figure that people would just boil the water, which is a very common method of purification that is extremely reliable.
• The Norsefire party was implied to have done this in the movie version of V for Vendetta.
• Halfway through Wild Beasts, it is discovered that the animals are acting crazy because there is PCP in the city's water supply.
• In Wild in the Streets, Max and his followers pour LSD into the Potomac River. All the politicians trip through the next day, allowing them to be easily led into voting to lower the voting age to 14.
• Zone 39: Central Union is considering misappropriating water from working-class towns to supply other areas with clean water.

Gamebooks

• The superhero-themed gamebook Appointment with F.E.A.R. have one encounter where you'll need to stop a madman who calls himself "The Poisoner" from contaminating the Titan City water reservoir.

Literature

• This is the basis of the lawsuit that drives the plot of The Appeal by John Grisham.
• Animorphs:
  • In #17, the Animorphs plan to contaminate the Yeerk Pool with instant maple and ginger oatmeal to turn all the Yeerks crazy. The Yeerk Pool isn't just their water source, it's their only source of nutrients, and they'll die if they can't swim in it every three days.^note There's an orbital Yeerk Pool on the aptly-named Pool Ship, but only the highest-ranking Yeerks would get taken there every three days, and the rest would be quietly killed along with their hosts, or just left to die, as we see in #8.
  • In #38, the Andalite commandos plan to release a Synthetic Plague into the Yeerk Pool, which has the possibility of also killing humans.
• In the first volume of the Books of the Raksura, in order to deal with a Fell occupation, the Indigo Cloud Raksura end up dumping a substance that kills Fell, makes Raksura very ill, and has no effect on most other groundlings into the court's water supply.
• Mentioned in A Dance with Dragons: Tyrion opines that Daenerys Targaryen is a fool for not poisoning every well within a 20-mile radius of her city of Meereen the moment she learned an enemy army was coming to lay siege. Tyrion notes that if she'd done so, the enemy's only water supply would have been a noxious nearby river that drinking from would have invited an outbreak of all manner of waterborne diseases within the ranks.
• In the Dirk Pitt Adventures book Sahara, the plot-driving ecological disaster is caused by the Corrupt Corporate Executive's improper disposal of nuclear waste that subsequently leaked into the water supply. At the end of the film, he gets subjected to Laser-Guided Karma — Dirk and Al have him tied down out in the open sun until he sunburns, then trick him into drinking that polluted water. He dies a raving loon.
• In Goldfinger, part of the Evil Plan to loot Fort Knox involves killing everyone in the area by poisoning the local town's water supply.
• Defied by Alastor Moody in his first appearance in Harry Potter and the Goblet of Fire: The known paranoid drinks only from his canteen, but it's a subversion as this conveniently allows an impostor to impersonate Moody by taking regular sips of Polyjuice Potion.
• "How It Was When the Past Went Away" by Robert Silverberg: Amnesia-inducing drugs are dumped in a city's water supply, leaving everybody in the city with no memory of who they are.
• In Jingo, there was a man who had poisoned the only well for twenty miles worth of desert, killing five men, seven women, thirteen children, and thirty-one camels (some of them being very valuable camels). This is the source of 71-Hour Ahmed's name. Once he had solid evidence and witness testimony to confirm guilt, he executed the poisoner before the customary three days of Sacred Hospitality was up, observing that the man would have tried to do it to him afterwards anyway.
• Done twice, for different reasons, in Stephen Fry's novel Making History. The first time, they put a water-soluble contraceptive in the well near the house where Adolf Hitler was born, thus preventing his birth. The second time, they put a dead rat in the same well, to prevent people from drinking it, because the world without Hitler turned out to be even worse.
• Night Chills, a novel by Dean Koontz, sees a government group test a form of More than Mind Control against a small town. The first stage was to dose the city's water supply with a hypnotic drug to make the townsfolk more susceptible to a series of subliminal programming they'd use during phase two.
• In a Prelude to Dune prequel novel, a group of Harkonnen soldiers manage to capture a young sandworm. Just for fun, they drown it in a hidden water tank near a Fremen village as punishment for hoarding water, knowing that pure Water of Life (the result of an infant worm regurgitating water, poisonous to it) is pure poison. When Liet Kynes later finds the village, most of the villagers are dead, while the rest are delirious and close to death. He puts them out of their misery and then slaughters a whole bunch of Harkonnens.
• Donald J. Sobol's Secret Agents Four. A criminal organization named Cobra plans to put a drug in the city of Miami's water supply. The drug causes the victim to relive the last 24 hours of their lives, rendering them helpless.
• Sherlock Holmes and Doctor Was Not: In "The Investigation into the Dawning Od", Dr. Otto Von Reichenbach poisons the water supply for the British troops bivouacked outside Bloemfontein with a magic potion that will transform those who have consumed it into monsters after they have returned to England.
• Star Trek: Stargazer: In The First Virtue, a fanatical Cordracite poisons her city's water supply in order to escalate a conflict with another race, assuming they'll be blamed.
• In This Other World, Bar-temah puts the drugs that cause Ha-Ran in the water supply in an attempt to stave off war with Makka by forcing people to empathize with each other. It backfires horribly — the tampering is discovered, Makka is blamed, and war breaks out.
• Tribesmen of Gor Fantasy Counterpart Culture to Arabs/desert dwellers; an outside party causes unrest by masquerading as one of two opposing tribes and attacking the others' oases. At one point they destroy a well, which tells Tarl's best friend of the book that they aren't really tribesmen because no tribesman, no matter how evil, would destroy a well.
• In the fifth book of The Underland Chronicles, we learn that the humans did this to the Diggers (giant moles) to steal their land.
• Wet Desert: Tracking Down a Terrorist on the Colorado River: When the bomber realizes that the All-American Canal is too heavily guarded for another bombing, he forces its shutdown with a bogus threat of having poisoned the water.
• The Wheel of Time: While discussing the total moral depravity of the Dark One's followers, one man reveals that the worst human being he ever knew was a shy, baby-faced young man who poisoned his town's well purely to cause suffering.
• In The Wishsong of Shannara, the Mord Wraiths poison Heaven's Well, the source of the Silver River, and the entire Four Lands sickens as a result.

Live-Action TV

• Batman (1966): The Joker turns the Gotham City water reservoir into strawberry jelly (that tastes like axle grease). As the Dynamic Duo works to undo this, Batman notes to Robin that the situation is affecting more than just the drinking water supply; if there was a fire while the water is in that state, the Fire Department would not be able to put it out.
• Blake's 7: In the pilot, the title character is told to not drink for three days because the Terran Administration is putting emotional suppressants in the water to keep the population docile (later, when Blake leaves the Domed City, he's encouraged to drink some Cool, Clear Water, but doesn't like the taste). In the final season, the Federation invents a drug that stops the production of adrenaline, refining it to such an extent that it can be introduced into the water or air, enabling the easy conquest of entire planets.
• Brimstone: In "Carrier", Stone has to stop a Poisonous Person before she can throw up in the local reservoir.
• Doctor Who:
  • In "The Sensorites", the eponymous species are being affected by a disease that the good guys later trace to a human expedition poisoning their water supply.
  • In "The Deadly Assassin", the title character pours a vial of poison into the only visible source of drinking water while battling the Doctor in the Matrix. The Doctor circumvents it entirely by digging up a pool of groundwater before using the poison in a blow dart against the assassin.
  • In "The Waters of Mars", the enemy is water-borne micro-organisms that get inside the base after the failure of a water filter.
• General and I: Bai Ping Ting has a water supply poisoned to defeat Chu Bei Jie.
• Get Smart: In "Is This Trip Necessary?", a Mad Pharmacist plans to put an enormous hallucinogen pill in the water supply, but is stopped by our heroes. When Max and 99 realise that, as a result, everyone will have a normal boring day tomorrow, they wonder if they did the right thing.
• The Goodies: In "Snooze", Graham invents a bedtime drink that works so well it puts the entire country to sleep. So he invents an antidote that speeds up the metabolism and plans to distribute it by going around with 24,000 gallons of concentrated antidote and putting a tablespoon in each river or reservoir. Unfortunately, the Goodies accidentally knock an entire drum-load in at once, and hilarity ensues as everyone starts running about at a rapid rate that increases whenever they take a drink.
• Highlander: In the multi-parter about the Horsemen of the Apocalypse, the Big Bad planned to contaminate water supplies with a bioweapon, For the Evulz.
• It's Always Sunny in Philadelphia: In "Lethal Weapon 5", Dennis and Mac star as Murtagh and Riggs investigating a Native American casino's involvement in "tainted tap water".
• Leverage: Played with. "The Three Days of the Hunter Job" sees the team Gaslighting a crooked reporter into believing that the water supply was tainted with a "self-replicating viral nerve agent" in order to discredit her when she reports it on live television.
• Merlin (2008): Nimueh conjured up an Afanc—a creature conjured using the Magic of the Elements of Earth and Water—magically transporting it inside an egg to the water supply of Camelot, where it hatched and caused a plague that killed dozens of citizens of Camelot, turning them pale with blue veins in the process.
• Monster Warriors: In "Last Ride of the Skeleton Crew", the Skeleton Crew—a small tactical strike team of living green skeletons—try to poison Capital City's water supply.
• The New Adventures of Robin Hood: In "The Prison", Robin finds out that Maddox, the leader of the revolt, has vials of a deadly plague, which he threatens to use to contaminate London's water supply, unless some of his men are released by the regional high lord, the Duke of Vortigern.
• Northern Exposure: One episode has Maurice tapping into an underground water source and starts bottling and selling the water. Everyone who drinks it begins displaying a number of Gender-Inverted Tropes.
• NUMB3RS: One episode involves a terrorist plot to put sarin gas into the Los Angeles water main. Not only would this kill anyone drinking the water, but also anyone taking a shower, doing the dishes, or being in the vicinity of sprinklers.
• The Pacific: In Ep 6, Peleliu Airfield, the thirsty U.S Marines on the hot island of Peleliu get excited over the news of someone finally finding water. As they happily collect much-need drinking water, another pair of Marines carefully checking the well fishes out the rotting carcass of a goat from the well, confirming that the Imperial Japanese had indeed poisoned it to deny the invaders.
• Power Rangers Dino Charge: In season 2's "Forgive and Forget", Heckyl plans to put Stingrage's modified venom, now amnesia-inducing rather than anger-inducing, into Amber Beach's water supply. Between the rangers' antidote and Stingrage's absorbing all the venom back from the water to power himself up, its intended effects don't last.
• Power Rangers Zeo: The Machine Empire tried to contaminate all the Earth's water in order to kill off humanity while at the same time turning it into something they could swim in.
• The Professionals: "Private Madness Public Danger" had a chemical expert threatening to contaminate London's water sources with a concentrated hallucinogenic drug unless his political demands were met. He starts with a few drops in the coffee dispenser of a chemical company, a hypodermic in a beer keg at a pub, and plans to disperse a gallon of ADX in a city reservoir.
• The Shannara Chronicles: In season 2, this turns out to be the Warlock Lord's plan; putting his blood in Heaven's Well, and thereby the Silver Lake and from there the whole water table of the Four Lands, turning everyone who drinks it into zombies under his control.
• Star Trek: The Next Generation:
  • "The Most Toys" has Kivas Fajo do this as part of a Poison and Cure Gambit — which itself is a cover for his real goal to get his hands on Data, so he can add a Soong-type android to his collection of rare items.
  • Played with in "Thine Own Self" when Data — who has amnesia and doesn't know about his own history or Starfleet — is accused of poisoning a well in the village he's living in, but he's really trying to cure them of radiation poisoning by putting the cure in the drinking water (resorting to subterfuge because the villagers don't trust him enough to take his cure if he offered it openly).
• The Twilight Zone (1959): In "Black Leather Jackets", the aliens plan to exterminate humanity by contaminating water reservoirs all over the world with deadly bacteria. Thousands of advance troops have been sent to Earth for that purpose. Steve reports to their leader that every living thing in the state will be dead within 48 hours.
• The X-Files: In "Anasazi", the shadowy organization puts LSD into Mulder's water supply, causing erratic behavior that discredits both him and the case he is currently following. And since it wasn't just Mulder's water supply, but his entire apartment building's, it also caused at least one murder there.

Music

• "Ghosttbusters" by Vargskelethor (AKA Vinesauce Joel) is about the protagonist poisoning the water supply, killing everybody.
  I poisoned the water supply
  Now everyone dead
  ...Oops.
  

Myths and Legends

• In some versions of Arthurian Legend, this is why King Uther dies — his enemies poison the castle's well.

Radio

• One episode of The Shadow had an unseen villain killing random people by poison and falsely claiming to be The Shadow. After the villain poisons the commissioner of the sanitation department, the real shadow figures out that the murderer is a sanitation worker who kills by putting poison into buildings' water supplies. He tracks the villain down and prevents him from dumping the poison into a rich neighborhood's water tower.
• According to the Canadian Broadcast Standards Council, a segment of CFNY-FM's The Dean Blundell Show from November 9, 2001, aired at 6:51 AM, had Todd Shapiro asking people on the street if they would "stop drinking tap water due to the threat of terrorists tampering with the water supply".

Tabletop Games

• BattleTech:
  • Malvina Hazen, the utterly insane khan of Clan Jade Falcon during the Dark Age, ordered one hapless planet's water supply to be contaminated with nuclear material because of a small group that had defied her on the planet. The planet in question was largely desert and had limited potable water, making this slightly more believable.
  • Stefan Amaris VII, proving to be just as mad and psychotic as his forebear, ordered the wells of an entire native enclave poisoned because they dared to defy his orders to move off their ancestral land. This act of wanton cruelty shocks his second in command as an act of needless barbarity, and indirectly leads to Duncan's Demons receiving assistance from the natives later in retribution for Amaris' treatment of their enclaves.
  • In what has to constitute one of the most creative war crimes ever committed, the Draconis Combine had the Mechs of their commando unit Sorensen's Sabres painted prior to the battle of Northwind, coating them with a special oil loaded with deadly bacteria, then sending them to fight at a water reservoir. The resulting battle caused the bacteria to wash off the Sabres' Mechs and infect the city's water supply, resulting in thousands of deaths after the Kuritan bioterror attack caused widespread toxic shock.
• Dungeons & Dragons:
  • The Al-Qadim setting has the heway, loathsome white serpents with poisonous scales. They're cunning and evil enough to swim around in oases and wells to contaminate them, giving them an easy source of food, and even if a drinker survives the poison, they're likely doomed anyway because now they have to find another source of water in a weakened state. For this reason, even dumb animals will try to kill heway whenever possible, though predators have to be careful not to bite the snakes.
  • One short adventure for Ravenloft involved a pair of devils that were poisoning a town's water supply with a toxin that induced hallucinations.
• The Illuminati card game and GURPS module has the "Fiendish Flouridators" as one of its many conspiracies.
• Magic: The Gathering has Poison the Well and Tainted Well, which can mess with your opponent's lands.
• Paranoia supplement Acute Paranoia, adventure "Outland-ISH". The high Programmer of ISH sector is putting a drug called ZAP! in the water supply for Infrared citizens. It tremendously increases productivity but eventually kills the drinker.
• In the Warhammer Fantasy backstory, when his undead armies couldn't conquer the kingdom of Nehekara, Nagash the Great Necromancer used Skaven mercenaries to poison the River Vitae (the setting's Expy of the River Nile) at its source, causing the river to turn black and its water to become lethal to any plant or animal that drank from it. The river became known as the River Mortis and is still deadly to drink from centuries later.
• In Warhammer 40,000, Genestealer Cults have been known to lace water supplies with Genestealer plague.

Theatre

• Holy Musical B@man! uses this, with a small parody of its use in Batman comics. When Sweet Tooth announces his plan to poison the water supply, several people comment about how it's worse than the last couple times a supervillain poisoned Gotham's water supply.
  Construction Worker: That nutjob Sweet Tooth is gonna poison the water supply!
  Pizza Girl: This is even worse than when The Joker poisoned the water supply!
  Construction Worker: Or when Scarecrow poisoned the water supply!
  Pizza Girl: Or when Killer Croc poisoned the water supply! That's how he died, the poor fool.

Video Games

• In The Adventures of Fatman, Toxicman plans to dump his toxic mutagen into the city's water supply.
• Astalon: Tears of the Earth: Algus, Arias, and Kyuli venture to the Tower of Serpents in hopes of saving their village after its water supply is poisoned.
• In Batman: Arkham Asylum, Scarecrow threatens to flood the Gotham river with his toxins and Joker pollutes the water flow to flood it with Titan.
• City of Heroes: Arachnos and the Rogue Isles' various Mad Scientists dump the waste from their mad-science projects into the Rogue Isles' sewer system, where it then gets processed into the Isles' water supply. The effects of this are most evident in the lower-level zones, such as Mercy Island and Port Oakes. Plagues and mutations are common. One of the early-game factions is the Infected, made up of citizens who have mutated into power-mad, barely-cognizant zombies from drinking the tainted water.
• Civilization:
  • Poisoning a city's water supply was a potential espionage action in Civilization II. Succeeding reduced the city's population.
  • You can do the same in Civilization IV, although instead of reducing the population directly, the city takes a huge "unhealthiness" penalty... which might just reduce the population.
• One Soviet mission in the Command & Conquer: Red Alert: Aftermath expansion pack is called "Don't Drink the Water" and involves using a supply truck to poison a river, which kills all Allied soldiers in a nearby outpost and allows you to capture a Chronosphere.
• One of the potential side quests in the first Diablo game involves Tristram's water supply being poisoned. When you go into the catacombs and find the spring, killing the monsters around it will turn it back to normal.
• Dragon Quest VII has Krage/Grondal, whose sole source of water is a single well in the middle of town. Then it gets spiked with a poison that makes everyone believe that they're the Demon Lord/King. Considerable amounts of Stupid Evil antics ensue until your merry band is able to do anything about it.
• Enclave President John Henry Eden in Fallout 3 attempts to convince the player to insert a container of novel Forced Evolutionary Virus into the water supply at Project Purity in an effort to achieve the Enclave's goal of killing everyone in the Capital Wasteland with the slightest degree of mutation. He says that the player character, having been born in a vault, is probably immune to the disease. He's wrong, because the player character was not Vault-born.
• Early on in Final Fantasy VI, Kefka does this to the kingdom of Doma in one of the definitive crossings of the Moral Event Horizon in console gaming, after the kingdom withstands the Empire's siege. After General Leo, who, despite being on his side, would never approve of such a thing, is called away, Kefka dumps poison in the river. Before long, virtually everyone in Doma Castle besides Cyan, a knight of the kingdom and a party member, is dead or dying.
• A side quest in Final Fantasy XIV has someone suspect that a farmer's paddy field is tainted with something due to the smell. You find out that a plant monster contaminated the water source, which was seeping into the fields and also likely contaminated the food being grown.
• Micaiah of Fire Emblem: Radiant Dawn rejects this as a tactic to take out a well-defended enemy base when it's suggested. Rather than point out the questionable ethics involved, she explains that people would see it as a questionable act, and start to question their motives, maybe turn against them.
• In Grim Dawn, an early quest has the player helping the survivor settlement at Devil's Crossing by fixing their water pump. Once it is repaired, the water that comes out is clearly poisoned and deadly to drink. This is caused by a species of local snake-men named the Slith, who secrete a poison from their bodies into the water that renders it undrinkable by humans. Once the player descends into their lair and kills the Slith's matriarch, the water clears up.
• Guild Wars 2: If you're playing as a human with the Street Rat background, an early personal story mission deals with a local gang that intends to poison Divinity Reach's well and loot everyplace they can while the population is too sick to fight back.
• A man in the first level of Half-Life 2 tells you not to drink the bottled water in City 17 because "they put something in it to make you forget".
• In Kult: Heretic Kingdoms, one of Alita's tasks is to go and stop some Taymurian shamans who are contaminating a river as part of their campaign against the army of Corwenth.
• Mass Effect: Andromeda: A quest on Kadara has Ryder and their team stumble across a small angaran settlement where everybody's died. Investigating reveals that some exiles had set up shop over in the next valley, and the leader of the settlement began gouging them for basic supplies. The exiles snuck into the settlement and sabotaged their water filters, which filtered out the sulphur in Kadara's water. By the time the angaran could've caught on, it was too late.
• Metal Gear Solid V: The Phantom Pain: The first story mission in Chapter 2 has Venom Snake shutting down an oil refinery that is leaking into a River in Africa, poisoning the local villagers. It turns out that this was done by XOF to try and dispose of an unneeded strain of vocal-chord parasite, which begins infecting the villagers.
• Pathfinder: Wrath of the Righteous: In a sidequest that's one great big homage to Fallout, you stumble upon a group of mineshaft-dwellers whose ancestors had sealed themselves inside a mine to ride out the cataclysm of the Worldwound opening. They need you to find out why their water supply has recently gone bad, which turns out to be a group of demons that had defiled the nearby temple from which the water flows, in order to flush them out.
• In The Sims Medieval, Spies and Wizards can put potions in the well. Some of them are beneficial, but they can add something like Vomicious Venom, which makes people throw up, or a sleeping potion.
• Uncharted 3: Drake's Deception: The secret of King Solomon's ifrit is eventually revealed to be a potent hallucinogen, hidden in the brass bottle, which he secretly introduced into the water supply of Ubar. After having primed the citizens of Ubar to believe he was going to unleash an ifrit upon them, and seeing as the city is in the middle of the desert and nobody had any choice but to drink the tainted water, they all had a catastrophic mass hallucination and set the city on fire themselves.
• We Happy Few: Just in case you thought you could get away with not taking your Joy in Wellington Wells, the water supply appears to have been laced with the medication. And, of course, you have to take a drink sometime...
• One potential chain of events in The YAWHG involves a potion getting dumped into the water, leading to horrifying mutations. A seperate Event Flag deals with a leech infestation. These events can get triggered in the same game, resulting in mutant leeches.

Web Animation

• SuperThings: The first news blip of the "News Zings Today" episode "Alarm! Poisoned Water!" involves breaking news of a contamination attack of the water source of Kaboom City, courtesy of the Double Acids. The two of them achieved this by having Count Garlik swim in the water plant's source water tank (minus his swim trunks), thus contaminating the water with garlic. Luckily for the city, and unluckily for the two of them and the remainder villains, they contaminated the line that goes to Prison Island, rather than the Kaboom City line.

Webcomics

• Buttersafe plays this for laughs.
• Mentioned in Drowtales at the council gathering as an example of how the "Queen's Law" (unwritten rules of clan warfare) has broken down.
• Saturday Morning Breakfast Cereal also has fun with this.
• Vixen: NYC: Maksai uses his transformation serum to contaminate New York's water supply, causing everyone who drank the water to turn into a feral human-animal hybrid. In this case, a single beaker full of the serum is enough to affect thousands of people around the city because the serum is magical in nature.

Web Videos

• Dr. Horrible's Sing-Along Blog:
  • In a prequel comic, the Evil League of Evil takes advantage of the city's superheroes going on vacation to try and poison the city's water supply. When Super Zero Johnny Snow thwarts them by freezing the entire water supply, they decide that's actually good enough and head back to their HQ.
  • And the song "My Eyes" has Dr. Horrible contemplating whether or not to do this. "Any dolt with half a brain/Can see that humankind has gone insane/To the point where I don't know if I'll upset the status quo/If I throw poison in the water main."

Western Animation

• In Action Man (2000), one of Dr. X's plots involved distributing an aggression-inducing formula as an energy drink. He later attempts to up the ante by dumping it in a reservoir.
• In Darkwing Duck, "Dry Hard" The Liquidator started out as an unscrupulous bottled water magnate who was contaminating the competitor's water in order to corner the market. He fell in a vat of his own poison and became a liquid being who could control all water.
• Drawn Together: Spanky distracts Princess Clara from interfering with his gay marriage to Xandir (for his health insurance) by telling her there's a Jew outside poisoning a well. Sure enough, Clara finds a rabbi outside but turns out he's just putting in water purification tablets.
• In Freakazoid!, at one point, The Lobe dumps laxatives into the town's reservoir.
• Grossology had a particularly disgusting example of this, with bonus points for being unintentional. The villainous Sloppy Joe had taken a trip to the water treatment plant where he was swimming in the water after it had been through the purification process leading several citizens, including main character Abby who prides herself on her strong stomach, to puke their guts out.
• Monster Allergy:
  • In one episode, the Gorkas were planning to spike the city's water supply, turning anyone who drank from it into Andro-Gorkas. Zick was able to thwart their scheme by evaporating the tainted water.
  • In another episode, this was a side effect of draining the fluids from the Healing Vat Magnacat had been in since his encounter with Bristlebeard the Pirate.
• The Simpsons:
  • In "Homer Loves Flanders", Homer says that Shelbyville vowed to spike Springfield's water supply in revenge for Springfield burning down their city hall, but "they don't have the guts". Three guesses what happens to Marge next.
  • In "G.I. (Annoyed Grunt)", in which Homer joins the Army Reserve, Homer is put in charge of a squad composed of the lowliest soldiers, and after Homer escapes the base where the war-game is held, the Colonel leads his battalion into nearby Springfield to hunt him down. Despite being told that his actions to capture one man wastes money and makes the Army look bad, the colonel insists on continuing his hunt. The occupation of Springfield only ends when Marge convinces everyone to pour alcohol into the reservoir, and once the battalion gets drunk and passes out, several gun-wielding residents surround the Colonel when he wakes up and Marge negotiates a truce.
• Spider-Man and His Amazing Friends: The Green Goblin had a plot to put goblin formula in New York City's water supply, goblinizing the whole population.
• SpongeBob SquarePants: Ultimately averted when Bubble Buddy wreaks havoc on Bikini Bottom.
  Tom: He poisoned our water supply, burned our crops, and delivered a plague unto our houses!
  Townspeople: He DID?
  Tom: No, but are we gonna sit around and wait till he does?!
• Heroic version used in Underdog where the titular hero dropped his super energy vitamin pills in all the world's water sources in order to give humanity the strength to fight back against the Mole Men after the villains stole all the food in the world.

Real Life

• In Medieval Europe, one of the motivations for anti-Semitic violence was that Jews were accused of poisoning the wells used by Christians, perhaps most infamously during The Black Death. This is the ultimate origin of the name of that logical fallacy.
  • Tragically (and ironically), there were a number of anti-Semitic riots and lynchings in late 12th-century Britain which ended with Jewish corpses and pieces thereof being dumped down a well, poisoning it after their deaths (most notably after the Clifford's Tower Massacre in York of 1190 AD — and the well they were dumped in supplied one of the richer Christian parts of town...)
• In the aftermath of the Great Kanto earthquake in 1923, ethnic Koreans were wrongly accused of taking advantage of the chaos and poisoning the local wells, leading to a massacre by the military and vigilantes that killed around 6000 people. The false rumor was based on the fact that the well water appeared murky and cloudy, but this is a common effect of earthquakes that was not known until decades later.
• In a campaign in Northern Africa during World War II, the Germans were upset to find a particular branch of Salt the Earth strategy: every oasis they came to had a sign in English stating that the oasis had been poisoned by the British army. When they complained that poisoning water constitutes a war crime, the British pointed out that there was absolutely nothing forbidding putting up false signs.
• British statesman Lord Chesterfield wrote in Letters to His Son: "I cannot omit, upon this occasion, telling you that the Eastern emperors at Constantinople (who, as Christians, were obliged at least to seem to favor these expeditions), seeing the immense numbers of the 'Croisez' [crusaders], and fearing that the Western Empire might have some mind to the Eastern Empire too, if it succeeded against the Infidels, as 'l'appetit vient en mangeant'; these Eastern emperors, very honestly, poisoned the waters where the 'Croisez' were to pass, and so destroyed infinite numbers of them." (letter 51)
  • It is also undoubtedly true that the Muslims had plugged (not poisoned; they expected to retake the territory eventually) the wells while retreating back to Jerusalem during the First Crusade. By the time the Crusaders took Jerusalem, they had nearly gone mad with thirst.
• In Flint, Michigan, the water supply was changed from the Great Lakes to the Flint River, notorious for filth. This caused many people to suffer from lead poisoning due to the increased acidity of the water corroding the town's lead pipes and caused national outrage at Governor Rick Snyder.
• During the Herero and Nama genocide that occurred in Namibia between 1904 and 1905, German colonial forces systematically poisoned wells in the desert.
• Attempted in the city of The Dalles, Oregon, in 1984. Members of the Rajneeshee cult planned to poison the water supply to make the residents sick so they could rig a city election and get their own cult members elected. The good news is that in the dry run, which involved poisoning salad bar food; they were implicated, compelled to withdraw their candidate, and ultimately tried and convicted for the poisoning & related crimes. The bad news is that about 750 people suffered from salmonella infection.
• In the beginning of the 6th Century BCE, the First Sacred War was fought between the Pylaeo-Delphic Amphictyony and the city-state of Kirrha. After besieging the city, the river that was its water source was first cut off, then allowed to flow again after it had been heavily contaminated with toxic hellebore plants. The city's defenders had immediately rushed to drink the poisoned water only to be incapacitated by the poison, leading to the city's fall and destruction and making this trope Older Than Feudalism.

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