In March 2004, a paralegal working for the city of Aliso Viejo, California, drafted an agenda item for the city council. The item proposed banning polystyrene foam containers from city events. Her reasoning was documented. The chemical used in their production, she had discovered, was linked to thousands of deaths annually. It accelerated corrosion of electrical equipment. It had been found in tumors. Governments had failed to regulate it. The chemical was dihydrogen monoxide. It was water.
The city council pulled the item before a vote. The embarrassment was immediate and public. But Aliso Viejo was not alone, and it was not the first, and it would not be the last.
Forty-nine percent. That was the number — nearly half of all Finnish parliamentary candidates surveyed in February 2011 who said they supported restricting "hydric acid, also known as dihydrogen monoxide." Politicians in Australia, New Zealand, and Canada had each, at separate moments across more than a decade, engaged seriously with the idea of banning water. Not because they were foolish. Because the joke was engineered to work.
The dihydrogen monoxide parody is one of the internet's oldest and most successful hoaxes — not because it deceived people once, but because it kept deceiving them, decade after decade, across continents, in parliaments and radio studios and science fairs. The joke never changed. The world kept falling for it.
To understand why, you have to understand what the internet was in the mid-1990s. The web was new. Information moved through it without gatekeepers, without context, without the institutional credibility checks that print media at least nominally maintained. A page that looked authoritative was authoritative, to most readers. Nobody had built the reflex yet. The DHMO parody arrived precisely at that moment of maximum vulnerability.
Its roots were older. Robert Heinlein had referenced "hydrogen monoxide" in his 1961 novel *Stranger in a Strange Land* — a literary wink that barely registered. In April 1983, the *Durand Express*, a weekly paper in Durand, Michigan, ran an April Fools' item warning that "dihydrogen oxide" had been found in the city's water pipes. It was a local joke, quickly forgotten. The real engine didn't ignite until 1989, when students at UC Santa Cruz began circulating photocopied fliers warning of campus DHMO contamination. By 1990, housemates at the same university had formalized the bit into the Coalition to Ban Dihydrogen Monoxide.
Craig Jackson sharpened it in 1994, building a website for the Coalition and cataloguing DHMO's dangers in the style of a genuine public health resource. The parody appeared in *Analog Science Fiction and Fact* in March 1996. Then Tom Way built DHMO.org in late 1997 — the version that would become definitive, complete with links to legitimate institutions like the EPA and NIH, lending the page an air of institutional adjacency that made skepticism feel paranoid rather than reasonable.
That same year, a fourteen-year-old named Nathan Zohner walked into the Greater Idaho Falls Science Fair with a project called "How Gullible Are We?" He handed fifty of his classmates a flier describing DHMO's properties — all accurate, all technically true, all framed to terrify. Forty-three of them signed a petition to ban it. Zohner won first prize. Journalist James K. Glassman, covering the story, coined a term: *Zohnerism*. The deliberate use of a true fact to lead a scientifically illiterate public toward a false conclusion.
The hoax scaled. In April 1998, a member of the Australian Parliament announced an international campaign to ban DHMO. In 2001, a staffer in New Zealand Green Party MP Sue Kedgley's office expressed support for banning what they called a "toxic substance." Radio host Neal Boortz announced in 2002 that Atlanta's water supply was contaminated with DHMO; a local television station covered it; the city's water authority issued a formal statement. In 2006, David Karem posted signs at a Louisville, Kentucky public fountain reading "DANGER! — WATER CONTAINS HIGH LEVELS OF HYDROGEN — KEEP OUT." In April 2013, two personalities at Gator Country 101.9 in Lee County, Florida were suspended after their DHMO broadcast prompted listeners to call the local utility company in alarm.
What made it strange wasn't the scale. It was the consistency. The parody worked on fourteen-year-olds and parliamentarians. It worked in 1990 and in 2013. It worked in Idaho and in New Zealand and in Finland. Every fact it cited was real. Dihydrogen monoxide does cause thousands of deaths annually — by drowning. It is found in tumors — because tumors, like all tissue, contain water. It does accelerate corrosion under certain conditions. The document never lied. That was the mechanism.
The anomaly that investigators and skeptics kept returning to was the institutional failure. In 2001, the New Zealand National Party publicly mocked Sue Kedgley's office for supporting the DHMO ban. Six years later, National Party MP Jacqui Dean wrote to Associate Minister of Health Jim Anderton asking whether DHMO should be regulated as a drug. The same party. The same joke. No institutional memory. Andrew Scheer, then a Canadian MP, published a media release on April 1, 2009, claiming to have introduced a bill banning DHMO from federal buildings — though his was a deliberate April Fools' gag, unlike many of the others.
What investigators confirmed was straightforward. Water's chemical formula is H₂O — two hydrogen atoms, one oxygen. "Dihydrogen monoxide" is a valid, if uncommon, systematic name under pre-2005 conventions. Under 2005 IUPAC nomenclature revisions, "oxidane" became the preferred systematic name, with "water" remaining fully acceptable. A mock material safety data sheet for DHMO has circulated for years. Dan Curtis Johnson created the Friends of Hydrogen Hydroxide website as a deliberate counter-parody — a foil to the Coalition page, adding another layer of absurdist infrastructure to the joke.
What remained contested was the Aliso Viejo incident's precise chain of events. The paralegal cited "poor research," but public records never fully documented how a DHMO-sourced document made it onto an official city council agenda without any intervening check catching it. The process that failed was never fully examined.
What the community came to believe — and what some researchers have argued seriously — is that the parody's repeated success is not primarily a story about ignorance. It's a story about chemophobia: the deeply wired human tendency to treat unfamiliar chemical names as inherently threatening. The parody exploits that reflex with surgical precision. Every "warning" it issues is framed in the language of risk communication that people have been trained to take seriously. Others have suggested the parody's survival online is partly intentional — kept alive by educators and skeptics who use it as a classroom demonstration. DHMO.org still exists. The Coalition to Ban Dihydrogen Monoxide still has a web presence. The joke is maintained.
The systematic scientific illiteracy of elected officials is the third theory, and the least comfortable one. Parliamentarians in at least four countries engaged seriously with the DHMO question across a span of thirteen years. None of them, in the documented cases, appear to have consulted a chemist before responding. The pattern is difficult to dismiss as coincidence.
DHMO.org remains live as of this writing. The parody is now old enough to be taught in schools — and it is, in some of them, as a lesson in media literacy and the rhetoric of fear. The joke has outlived the internet era that birthed it, migrated through social media, and still occasionally surfaces as a genuine alarm. In 2018, a noticeboard at Wuling Farm in Taiwan warned visitors they were "using dihydrogen monoxide" at apple orchards — framed as a pesticide warning, intended to deter theft. Farmers weaponized the hoax without knowing its history.
The question the parody keeps asking isn't whether people are stupid. It's whether the gap between scientific language and public understanding is so wide that almost anyone, given the right framing, can be walked across it. Forty-three out of fifty signatures. Forty-nine percent of parliamentary candidates. The numbers don't change much, no matter who you ask.