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Where there is life, there is water.
—Hama, Avatar the Last Airbender, episode The Puppetmaster
3-D model of H2O.
It matters
Icon chemistry.png
Action and reaction
Spooky scary chemicals
Er, who's got the pox?

Water (H2O) is a chemical compound. Each molecule consists of two hydrogen atoms and one oxygen atom sharing covalent bonds. Its chemical name is dihydrogen monoxide. Water is fundamental for life as we know it to exist. Water is also one of the most abundant compounds in the universe.

Given water's importance for life as we know it to exist, water has played a seminal role in the mythologies and religions of peoples around the world since time immemorial. Unfortunately, those same properties also make water excellent woo material.

Chemical properties[edit]

Schematic diagram of a water molecule. The dots represent valence electrons and the bars covalent bonds.
But when you back up a bit, it looks like this.

Water is an excellent solvent and it is often referred to as the "universal solvent" or even the "solvent of life". The water molecule's structure is responsible for this, since the electrons are unevenly distributed throughout the molecule. One end of the molecule with greater electron density is slightly negative and the other end is slightly positive. Water and related compounds are said to be "polar". Water generally dissolves other substances that are also polar.

Non-polar substances, like oil, will not dissolve in water. Water's polar nature explains many of its properties, some of them essential for life as we know it, like its (relatively) high melting and boiling points, high surface tension, and that it expands while freezing (in other words, unlike many other substances, solid water (ice) is less dense than liquid water).

Non-polar substances can be made to be soluble in water by using detergents (also called surfactants) that are large molecules with a polar end and a non-polar end. The polar end is attracted to water molecules and the non-polar end to the non-polar greasy substances.[1]

Water in the Universe[edit]

Pluto has a heart of ice.

Carbon, hydrogen, oxygen, and nitrogenWikipedia are the most common elements in the cosmos. Unsurprisingly, water is the most abundant compound in the universe,[2] and can be found everywhere: from some craters of the polar regions of the Moon to a very distant quasar.[3] As water is essential for life as we know it, finding water outside of Earth is an important topic of research in astrobiology. Until recently, Earth was the only place of the Universe where liquid water had been observed. This has changed with the discovery of subglacial lakes beneath the Martian south pole.[4][5]

NASA probe Cassini has found strong evidence for the presence of a subsurface ocean beneath the icy surface of EnceladusWikipedia one of Saturn's moons.[6] Enceladus has been found to have hydrothermal ventsWikipedia[7] There is also strong evidence that Jupiter's moon Europa has liquid oceans under its surface of solid ice.[8]

Traditional consensus holds that Mars' oceans were evaporated by an increasingly strong solar wind over billions of years, as the planet's gravity was not strong enough to hold on to its oceans. A 2021 study, however, indicates that Mars' water didn't disappear into the cosmic void; instead, it's been sequestered away into the Martian crust.[9]

Water has been detected in the discs of newly born solar systems, and in the molecular clouds present in interstellar space.[10] Water vapor has also been detected in the atmosphere of an extrasolar gas giant.[11] The exoplanet in question is located in the habitable zone of its host star, but isn't suspected to have life (as we know it) because life kind of has a hard time developing on non-terrestrial worlds. However, said exoplanet is suspected to have clouds of water vapor, and perhaps even rain.[11]

Pluto is also suspected to have a possible subterranean ocean of liquid water.[12] The reason for this being is that Pluto's surface shows features concordant with geological activity. If Pluto were a dead, cold hulk from the start, we'd expect the surface of Pluto to be a lot more compressed, especially with material dating back to the formation of the Solar System. We don't see that compression.[12] What we instead see is that Pluto was formed hot and then slowly froze over time, expanding outward as it froze. Water expands when it freezes. So did Pluto. Ergo, Pluto probably had a mantle of liquid water early in its history, and possibly still does so today.[12]

Pluto's moon Charon is also suspected to have possessed a subsurface ocean at some point. The reason this is suspected is because Charon shares the same "expanding ice" feature that Pluto does.[13] The Ice Belt has a lot of slush, it seems.

Ganymede, one of the Galilean moons of Jupiter, is also (strongly) suspected to have a subsurface ocean. The amount of water in said ocean is thought to surpass the total water content of the Earth's hydrosphere.[14] Ganymede is the only moon known to possess its own magnetic field. Given that Ganymede's magnetic field interacts with Jupiter's magnetic field, it has allowed scientists to get some insight into the composition of Ganymede's interior.[14][note 1] The scientists hypothesized that if Ganymede possessed a saltwater ocean, Jupiter's magnetic field would create a secondary field that would effectively counter Jupiter's field. What they found is that the ocean reacts so strongly to Jupiter's magnetic field that it reduces the "rocking" of Jupiter's and Ganymede's respective aurorae by a full 2 degrees, instead of the expected 6 degrees if the ocean was not present.[15] Ganymede is also suspected to harbor multiple flayers of oceans and ice, overlaying each other like stratified sediment.[16]

Water and life[edit]

Many astrobiologists consider the presence of liquid water to be a necessary condition for the development of life. While this is a bit earth-centric, it is quite likely true for chemical life as we are familiar with it. The existence of liquid water on habitable worlds is one of the key variables of the Drake equation.

Regarding Enceladus, the aforementioned hydrothermal activity possibly drives complex chemistry, which has implications for the presence of extraterrestrial life on Enceladus.[17] Studies have been done which show that Enceladus' hydrothermal vents are potentially habitable for terrestrial hydrothermal vent microorganisms.[18] The presence of methane detected within Enceladus' plumes could have been generated by hypothetical organisms dwelling within and around Enceladus' hydrothermal vents.[18]

Studies have concluded that the ancient water on Mars may have been too saline for most comparable terrestrial life to withstand.[19]

Ganymede's oceans are also thought to interact with the geology of Ganymede, meaning that Ganymede's oceans are chemically active.[14] It is hypothesized that life on Earth arose out of complex chemistry occurring at hydrothermal vents.[20] If Ganymede possesses hydrothermal vents, this may indicate prebiotic chemistry is occurring on Ganymede.[16]

Water on Earth[edit]

On Earth, water exists naturally in all three states, as ice, liquid water, and water vapor. The water cycle drives most of our weather, by transporting large amounts of energy received from the sun into the atmosphere, where it can then move from place to place, often forming large cyclonic patterns due to the Earth's rotation.[21]

Once upon a time, our planet was covered by a global ocean.[22] If we were around back then, we probably would've called this rock "Water" and not "Earth".

How Earth got water is not fully determined. The dominant hypotheses suggest that meteorites or comets littered Earth with liquid water or otherwise helped form the water, but an August 2020 study published in Science suggests that at least a portion of the water may have already formed during Earth's building process, as the deuterium-to-hydrogen ratio in common meteorites were similar to the ratio inside Earth.[23]

Water and religion[edit]

Baptism in water is a common ritual in many religions.

Water has long been recognized as important for life to exist. This ancient knowledge is reflected in humanity's myths and legends.[24] Water has also been given a "cleansing" nature, and rituals have been developed to "cleanse" the person of their "sin". Christianity, for instance, has the ritual of baptism, wherein a new convert or newborn is doused in "holy water" to signify that they are freed from the "taint" of original sin and "born again" under Christ's saving grace.[25] Whether or not this ritual is effective cannot be tested at the current time.

Islam also holds water to be sacred. Gifting water is considered to be the most blessed act of charity in Islam.[26] Water is used as a cleansing agent in wudu, or ablution.Wikipedia[26]


See the main article on this topic: Water woo

As water has historically been one of the most important substances to humanity, it makes sense that a lot of myths, misconceptions, and even conspiracy theories would eventually arise regarding water. However, it became particularly bad with the advent of capitalism, as unscrupulous businessmen wanted to find ways to sell something for loads of money that most people in the developed world can virtually get for free.[27] As a general rule of thumb, unless your tap water is contaminated (e.g. the Flint water crisis), it's best to just drink tap water.

Bottled water[edit]

See the main article on this topic: Bottled water

For some reason, there is a common perception that bottled water is cleaner or tastier than the water you can get from the tap. In reality, the differences between them are minimal, and tap water is often safer because it is more strictly regulated, meaning that for the most part bottled water is just a scam that results in unnecessary plastic pollution. In fact, oftentimes bottled water really is just tap water (Pepsi's Aquafina is an infamous case), and even when it isn't there are concerns with private companies like Nestlé unsustainably harvesting water that should belong to the local communities and environments.[28]

Specialized water[edit]

There are various types of treated water, such as hydrogen water, oxygenated water, magnetic-treated water, and Kabbalah water that are often advertised as sorts of miracle cures that are so much healthier than regular water. Needless to say, in most cases you will get the same result drinking water from the tap. Raw water is particularly stupid, as it's just water that hasn't been treated for pathogens and other contaminants, making it ridiculously unsafe to drink.


See the main articles on this topic: Homeopathy and Water memory

Homeopathy is based on the "principles" that something that causes symptoms of a disease can be used to treat it and diluting a solution makes it stronger. Needless to say, that is the opposite of how things work in reality. Particularly important to homeopathy is the idea that water can "remember" the various molecules that it used to have in it.[29] If this was true, it would make basically anything a homeopathy panacea.


See the main article on this topic: Water fluoridation

Fluoride salts are often added to tap water in order to improve the dental health of the general public. This issue has been studied for decades, and there is an overwhelming consensus among public health experts that it is safe;[30] despite this, many conspiracy theorists are virulently opposed to water fluoridation.

Dihydrogen monoxide[edit]

Somebody has to do something!!
Dihydrogen monoxide, or, "How I learned to use technical jargon to feel self-superior and get a cheap laugh at the expense of others."

Dihydrogen monoxide (frequently abbreviated DHMO) is an incredibly dangerous chemical that must be banned to save the children alternative name for water based on its chemical composition. The use of technical jargon lends an air of danger to an everyday substance. One can then list a range of harmful effects associated with the chemical, playing upon the listeners' chemophobia, thus leading people to believe that dihydrogen monoxide poses a threat to public safety and should be banned. People who fall for this can then be called gullible misguided. Great hilarity will then ensue.[31]

There is actually an important point to be made about the dihydrogen monoxide stunt. As the above shows, it can be tough to tell the difference between real science and a deliberate hoax. Often, we have to take accredited scientists at their word when they tell us about complicated topics such as black holes, quantum mechanics, brain physiology, or any number of other topics that the lay person probably does not really understand. People generally hold scientists in high regard. Alas, the scientifically illiterate often "reason", if one can call it such, according to fear, uncertainty, and doubt. Even intelligent people are sometimes taken in and hilarity may not be justified. This may help explain why otherwise smart people can fall for pseudoscience.

Icon fun.svg For those of you in the mood, RationalWiki has a fun article about Dihydrogen monoxide.

See also[edit]


  1. Ganymede's magnetic field lies within Jupiter's magnetic field. When Jupiter's magnetic field changes, Ganymede's field changes also. The aurorae "rock" each other, in a sense.


  1. "Ask a Scientist" - Retrieved from the Archive
  2. Water - The most abundant compound in the Universe - Science Is Life
  3. Astronomers Find Largest, Most Distant Reservoir of Water
  4. Seu, R.; Restano, M.; Noschese, R.; Nenna, C.; Mitri, G.; Masdea, A.; Martufi, R.; Giuppi, S. et al. (25 July 2018). "Radar evidence of subglacial liquid water on Mars". Science 361 (6401): 490–493. arXiv:2004.04587. Bibcode 2018Sci...361..490O. doiWikipedia:10.1126/science.aar7268. PMID 30045881. eaar7268. 
  5. Lauro, Sebastian Emanuel (28 September 2020). "Multiple subglacial water bodies below the south pole of Mars unveiled by new MARSIS data". Nature Astronomy 5: 63–70. arXiv:2010.00870. Bibcode 2021NatAs...5...63L. doiWikipedia:10.1038/s41550-020-1200-6. Retrieved 25 November 2022. 
  6. "Cassini finds global ocean in Saturn's moon Enceladus" - NASA
  7. Waite, Jack Hunter Jr.; Glein, C. R.; Perryman, R. S.; Teolis, Ben D.; Magee, B. A.; Miller, G.; Grimes, J.; Perry, M. E. et al. (2017). "Cassini finds molecular hydrogen in the Enceladus plume: Evidence for hydrothermal processes". Science 356 (6334): 155–159. Bibcode 2017Sci...356..155W. doiWikipedia:10.1126/science.aai8703. PMID 28408597. 
  8. Europa, NASA
  9. "New study challenges long held theory of fate of Mars' water" - JPL press release
  10. The Solar System and beyond is awash in water" - JPL"
  11. 11.0 11.1 Water vapor detected in the atmosphere of an exoplanet in the habitable zone" - Smithsonian Magazine
  12. 12.0 12.1 12.2 "Pluto has likely maintained an underground liquid ocean for billions of years" - Astronomy Magazine
  13. Pluto's hulk like moon Charon - a possible ancient ocean? - NASA
  14. 14.0 14.1 14.2 In Depth - Ganymede - NASA
  15. "HubbleWikipedia observations suggest underground ocean on Jupiter's largest moon" - NASA
  16. 16.0 16.1 "Ganymede may harbor 'club sandwich' of oceans and ice" - NASA
  17. Postberg, Frank (June 27, 2018). "Macromolecular organic compounds from the depths of Enceladus". Nature 558 (7711): 564–568. Bibcode 2018Natur.558..564P. doiWikipedia:10.1038/s41586-018-0246-4. PMC 6027964. PMID 29950623. 
  18. 18.0 18.1 Taubner, Ruth-Sophie; Pappenreiter, Patricia; Zwicker, Jennifer; Smrzka, Daniel; Pruckner, Christian; Kolar, Philipp; Bernacchi, Sébastien; Seifert, Arne H. et al. (2018-02-27). "Biological methane production under putative Enceladus-like conditions". Nature Communications 9 (1): 748. Bibcode 2018NatCo...9..748T. doiWikipedia:10.1038/s41467-018-02876-y. ISSN 2041-1723. PMC 5829080. PMID 29487311. 
  19. Tosca, Nicholas J.; Knoll, Andrew H.; McLennan, Scott M. (2008). "Water Activity and the Challenge for Life on Early Mars". Science 320 (5880): 1204–7. Bibcode 2008Sci...320.1204T. doiWikipedia:10.1126/science.1155432. PMID 18511686. 
  20. "Hydrothermal vents and the origin of life". Nature Reviews Microbiology. 2008. doiWikipedia:10.1038/nrmicro1991. 
  21. Introduction to the water cycle by NASA
  22. "Earth was once a waterworld" - International Business Times
  23. Pelsier, A. (August 28, 2020). The origins of water. Science, 369(6507), p1058. doi:10.1126/science.abc1338
  24. Larbi Bouguerra, Mohamed (2005). Water: Symbolism and Culture. Institut Veolia Environment.
  25. "What is baptism?" - "Learn"
  26. 26.0 26.1 "The importance of water in Islam" - Islamic Help
  27. "Under capitalism even water is a tool of oppression" - Monthly Review
  28. Nestle's Water Controversy, Explained, Hope Ngo, Mashed 27 December 2021
  29. What is 'water memory'" - Live Science
  30. CDC primer on water fluoridation
  31. Snopes