"Dihydrogen monoxide" redirects here. For the article on the H2O molecule, see water (molecule).
The dihydrogen monoxide hoax involves listing negative effects of water while using an unfamiliar scientific name for it, then asking individuals to help control the seemingly dangerous substance. The hoax is designed to illustrate how the lack of scientific knowledge and an exaggerated analysis can lead to misplaced fears. Dihydrogen monoxide, shortened to DHMO, is a scientific name for water that, while technically correct, is almost never employed.
The hoax was apparently created by Eric Lechner, Lars Norpchen and Matthew Kaufman, housemates while attending UC Santa Cruz in 1989, revised by Craig Jackson in 1994, and brought to widespread public attention in 1997 when Nathan Zohner, a 14-year-old student, gathered petitions to ban "DHMO" as the basis of his science project, titled "How Gullible Are We?"
may cause electrical failures and decreased effectiveness of automobile brakes.
has been found in excised tumors of terminal cancer patients.
Despite the danger, dihydrogen monoxide is often used:
as an industrial solvent and coolant.
in nuclear power plants.
in the production of styrofoam.
as a fire retardant.
in many forms of cruel animal research.
in the distribution of pesticides. Even after washing, produce remains contaminated by this chemical.
as an additive in certain "junk-foods" and other food products.
The original webpage is no longer accessible, but it has been mirrored by The Internet Archive: Ban Dihydrogen Monoxide!
"Dihydrogen monoxide" may sound dangerous to those with a limited knowledge of chemistry or who hold to an ideal of a "chemical-free" life. The term monoxide has negative connotations due to its being part of the name of the highly toxic carbon monoxide.
Literally, the term "dihydrogen monoxide" means "two hydrogen, one oxygen", consistent with its molecular formula: the prefix di in dihydrogen means "two", the prefix mono in monoxide means "one", and an oxide is a compound that contains one or more oxygen atoms.
The use of numerical prefixes is typical nomenclature for compounds formed by covalent bonds, which are present in water. The prefix for the first named element is often dropped if the elements involved commonly form only one compound, or even if the number of atoms of the first-named element is the same in all the compounds of the two (or more) elements. Thus H2S is often simply called hydrogen sulfide, and lithium oxide is a common name for Li2O. However, the names dihydrogen sulfide, dilithium oxide, and dilithium monoxide are also commonly used both in industry and in universities.
The mono- prefix is often dropped for the second-named element if it is the only common compound the elements form. Thus referring to H2S as hydrogen monosulfide is much rarer than the name hydrogen sulfide. However, since carbon and oxygen can form several compounds (carbon monoxide, carbon dioxide, tricarbon dioxide, and dicarbon monoxide), the mono- prefix is kept, as it is with silicon monoxide and silicon dioxide. Indeed, hydrogen and oxygen do form another common compound, H2O2. Using prefix nomenclature this compound would be called dihydrogen dioxide—also known as hydrogen peroxide. Thus, keeping the mono- in dihydrogen monoxide does serve to distinguish it from another compound.
Water has a regular scientific or systematic name of hydrogen oxide, as well as an alkali name of hydrogen hydroxide and several acid names such as hydroxic acid, hydroxylic acid, and hydroxilic acid. Incidentally, the term "hydroxyl acid" used in the original hoax is slightly incorrect, as it does not follow convention. Additional names of μ-oxido dihydrogen and oxidane have been developed for this compound.
Water is not a systematic chemical name under any recognized nomenclature, nor is it international. It also is not the term normally used for the solid or gaseous forms. Under the 2005 revisions of IUPAC nomenclature of inorganic chemistry, there is no single correct name for every compound.  The primary function of chemical nomenclature is to ensure that the person who hears or reads a chemical name is under no ambiguity as to which chemical compound it refers: each name should refer to a single substance. It is considered less important to ensure that each substance should have a single name, although the number of acceptable names is limited. Water is one acceptable name for this compound.
Public efforts involving DHMO
In 1989, Eric Lechner, Lars Norpchen and Matthew Kaufman circulated a Dihydrogen Monoxide contamination warning on the UC Santa Cruz Campus via photocopied fliers. The concept originated one afternoon when Matthew recalled a similar warning about "Hydrogen Hydroxide" that had been published in his mother's hometown paper, the Durand (Michigan) Express, and the three then worked to coin a term that "sounded more dangerous". Eric typed up the original warning flier on Matthew's computer, and a trip to the local photocopying center followed that night.
In 1994, Craig Jackson created a web page for the Coalition to Ban DHMO. The page spread widely on the net and off, including publication as an "ad" in a 1995 issue of Analog Magazine.
The Friends of Hydrogen Hydroxide was created partly as a foil on the Coalition page, to provide evidence of 'misguided' supporters of dihydrogen monoxide. This form of collaborative connivance is a classic tool of internet spoofers.
In 1997, Nathan Zohner, a 14-year-old junior high student at Eagle Rock Junior High School in Idaho Falls, Idaho, gathered 43 votes to ban the chemical, out of 50 people surveyed among his classmates. Zohner received the first prize at Greater Idaho Falls Science Fair for analysis of the results of his survey. In recognition of his experiment, journalist James K. Glassman coined the term "Zohnerism" to refer to "the use of a true fact to lead a scientifically and mathematically ignorant public to a false conclusion."
In 1997, drawing inspiration from Jackon's web page and Zohner's research, Tom Way created the Dihydrogen Monoxide Research Division web site as a fun and educational resource for teaching about critical thinking and information literacy.
In 2001 a staffer in New Zealand Green Party MP Sue Kedgley's office responded to a request for support for a campaign to ban dihydrogen monoxide by saying she was "absolutely supportive of the campaign to ban this toxic substance". 
Kate Dalgleish and Mikael Sydor, high school students from Calgary, Alberta, Canada, circulated a petition in April 2004 to ban the chemical as part of the Western Canada High School film festival. Several high school chemistry teachers and university science students signed the petition, which asked the municipal government to ban the 'dangerous chemical' under a fictitious Hazardous Chemical Act. Their film won the film festival.
The idea was used for an episode of the Penn & Teller show Bullshit!, in which they had self-proclaimed environmentalists sign a petition to ban DHMO.
In March 2004, Aliso Viejo, California almost considered banning the use of foam containers at city-sponsored events because dihydrogen monoxide is part of their production. A paralegal had asked the city council to put it on the agenda; he later attributed it to poor research. The law was pulled from the agenda before it could come to a vote, but not before the city received a raft of bad publicity.
Teams in a 2005 version of The Game circulated a petition to ban dihydrogen monoxide at Fisherman's Wharf in San Francisco, California—while dressed in superhero costumes.
In 2005 at "Tent State University", a week long anti-war event at Rutgers University, members of the conservative publication The Rutgers Centurion gathered signatures from the protesters on a petition calling for a ban on Dihydrogen Monoxide.
In 2006, in Louisville, Kentucky, David Karem, executive director of the Waterfront Development Corporation, a public body that operates Waterfront Park, which features a large, accessible public fountain, wished to deter bathers from using the fountain. "Counting on a lack of understanding about water's chemical makeup," he arranged for signs reading: "DANGER WATER - CONTAINS HIGH LEVELS OF HYDROGEN - KEEP OUT to be posted on the fountain at public expense.
An online petition to the British prime minister was correctly identified by the prime minister's office as a hoax, and rejected.
In one episode of the children's science show How 2, Fred Dinenage used a glass of water in a perspex box to carry out the hoax, before drinking the water then explaining the truth.
In 2007 Jacqui Dean, New Zealand National Party MP, fell for the hoax, writing a letter to Associate Minister of Health Jim Anderton asking "Does the Expert Advisory Committee on Drugs have a view on the banning of this drug?" 
^ abc Dihydrogen Monoxide from Urban Legends Reference Pages, accessed 25 September 2006.
^ ab IUPAC Report: General Aims, Functions and Methods of Chemical Nomenclature (March 2004) http://www.iupac.org/reports/provisional/abstract04/RB-prs310804/Chap1-3.04.pdf
^ The original poster circulated at UC Santa Cruz (PDF)
^ Glassman, James K. "Dihydrogen Monoxide: Unrecognized Killer", The Washington Post, 1997. Retrieved on 2007-03-08.
Gnad, Megan (2007-09-14). MP tries to ban water. New Zealand Herald.
^ Local officials nearly fall for H2O hoax, at MSNBC 15 March 2004, accessed 25 September 2006.
^Water without hydrogen would warrant warning, Louisville Courier-Journal, Monday, July 17, 2006 (link inactive as of Friday, May 18, 2007)