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:''This article focuses on water as it is experienced in everyday life. See [[Water (molecule)]] for information on the chemical and physical properties of pure water (H<sub>2</sub>O, hydrogen oxide), and [[Water (film)]] for the movie of the same name.''

[[Image:A girl in a swimming pool - underwater.jpg|255px|thumb|right|A girl in a [[swimming pool]] ]]
{{portal}}
'''Water''' (from the [[Old English language|Old English]] ''waeter''; c.f [[German language|German]] "Wasser", from [[PIE]] ''*wod-or'', "water"), in its pure form, is a [[taste]]less, [[odor]]less substance that is essential to all known forms of [[life]] and is known also as the most ''universal [[solvent]]''. It appears [[color]]less to the naked eye in small quantities, though it can be seen to be [[blue]] in large quantities or with scientific instruments <ref>[http://www.deepocean.net/deepocean/index.php?science07.php The Color of Water: Visibility Under Water]</ref>. An abundant substance on [[Earth]], it exists in many places and forms. It appears mostly in the [[oceans]] and polar [[ice cap]]s, but also as [[cloud]]s, [[rain|rain water]], [[river]]s, freshwater [[aquifer]]s, and [[sea ice]]. On the planet, water is continuously moving through the [[water cycle|cycle]] involving [[evaporation]], [[precipitation (meteorology)|precipitation]], and [[runoff (water)|runoff]] to the [[sea]].

Water fit for [[human]] consumption is called [[drinking water]] or "potable water". Water that is not specifically made for drinking, but is not harmful for humans when used for food preparation is called [[safe water]].

This natural resource is becoming more scarce in certain places, and its availability is a major social and economic concern. This may be referred to as the "water bubble", in analogy to the [[dot-com bubble]].

Currently, about 1 billion people around the world routinely drink unhealthy water. Most countries have accepted the goal of halving by 2015 the number of people worldwide who do not have access to [[safe water]] and [[sanitation]] during the [[29th G8 summit|2003 G8 Evian summit]] <ref> [http://www.g8.fr/evian/english/navigation/2003_g8_summit/summit_documents/water_-_a_g8_action_plan.html G8 "Action plan" decided upon at the 2003 Evian summit] </ref>. Even if this difficult goal is met, it will still leave more than an estimated half a billion people without access to safe drinking water supplies and over 1 billion without access to adequate sanitation facilities. Poor water quality and bad sanitation are killers; some 5 million deaths a year are caused by polluted drinking water.

Hardly surprising, since in the developing world, 90% of all wastewater still goes untreated into local rivers and streams. Some 50 countries, with roughly a third of the world’s population, also suffer from medium or high water stress, and 17 of these extract more water annually than is recharged through their natural water cycles {{fact}}. The strain affects surface freshwater bodies like rivers and lakes, but it also degrades groundwater resources.

== Molecular properties ==
{{main|Water (molecule)}}
[[Image:Water molecule dimensions.png|right|235px| ]]
Water has the [[chemical formula]] [[hydrogen|H]]<sub>2</sub>[[oxygen|O]], meaning that one [[molecule]] of water is composed of two [[hydrogen]] [[atom]]s and one [[oxygen]] atom. It can also be described ionically as HOH, with a hydrogen [[ion]] (H<sup>+</sup>) that is bonded to a [[hydroxide]] ion (OH<sup>-</sup>). It is in [[dynamic equilibrium]] between the [[liquid]] and [[vapor]] states at [[standard temperature and pressure]]. At [[room temperature]], it is a nearly [[colorless]], [[taste]]less, and [[odorless]] liquid. It is often referred to in the sciences as ''the [[universal]] [[solvent]]'' and the only pure substance found naturally in all three [[states of matter]].

=== Forms of water ===
[[Image:SnowflakesWilsonBentley.jpg|right|thumb|235px|[[Snowflake]]s by [[Wilson Bentley]], 1902]]
{{seedetails|:Category: Forms of water}}

Water takes many different shapes on Earth: [[water vapor]] and [[cloud]]s in the sky, [[wave]]s and [[iceberg]]s in the [[sea]], [[glacier]]s in the [[mountain]], [[aquifers]] in the ground, to name but a few. Through [[evaporation]], [[precipitation (meteorology)|precipitation]], and [[runoff (water)|runoff]], water is continuously flowing from one form to another, in what is called the '''[[water cycle]]'''.

Because of the importance of precipitation to [[agriculture]], and to [[mankind]] in general, different names are given to its various forms: while [[rain]] is common in most countries, other phenomena are quite surprising when seen for the first time. [[Hail]], [[snow]], [[fog]] or [[dew]] are examples. When appropriately lit, water drops in the air can [[refract]] [[sunlight]] to produce [[rainbow]]s.

Similarly, water runoffs have played major roles in human history as [[river]]s and [[irrigation]] brought the water needed for agriculture. Rivers and [[sea]]s offered opportunity for [[travel]] and [[commerce]]. Through [[erosion]], runoffs played a major part in shaping the environment providing river [[valley]]s and [[river delta|deltas]] which provide rich soil and level ground for the establishment of population centers.

Water also infiltrates the ground and goes into [[aquifer]]s. This [[groundwater]] later flows back to the surface in [[spring (water)|springs]], or more spectacularly in [[hot spring]]s and [[geyser]]s. Groundwater is also extracted artificially in [[water well|well]]s.

Because water can contain many different substances, it can taste or smell very differently. In fact, humans and other animals have developed their senses to be able to evaluate the drinkability of water: animals generally dislike the taste of [[salt]]y [[sea water]] and the putrid [[swamp]]s and favor the purer water of a mountain spring or aquifer.

=== Water in biology and human civilization ===
[[Image:Drinkingwater.JPG|thumb|[[Drinking water]] from a [[Tap (valve)|tap]]]]

From a [[biology|biological]] standpoint, water has many distinct properties that are critical for the proliferation of [[life]] that set it apart from other substances. Water carries out this role by allowing [[organic compound]]s to react in ways that ultimately allows [[replication]]. It is a good [[solvent]] and has a high [[surface tension]], and thus allows organic compounds and living things to be transported in it. Fresh water has its greatest [[density]] under normal atmospheric pressure at 4 °[[Celsius|C]], then becoming less dense as it [[freezing|freezes]] or [[heat]]s up from this point. As a stable, [[polar molecule]] prevalent in the atmosphere, it plays an important role as a [[greenhouse effect|greenhouse gas]] absorbing [[infrared radiation]], without which, Earth's average surface temperature would be &minus;18 ° Celsius. Water also has an unusually high [[specific heat capacity|specific heat]], which allows it to play many roles in regulating global and regional [[climate]]. Because it absorbs strongly in the infrared portion of the [[light spectrum]], a small amount of visible red light is absorbed as well, resulting in water's slightly blue color when seen in mass quantities such as a lake or ocean.

Water is a very good [[solvent]], dissolving many types of substances, such as various [[salt]]s and [[sugar]]. It facilitates [[chemical reaction|chemical interactions]] such as the process of [[metabolism]].

Some substances, however, do not mix well with water, including [[lipid]]s, some [[protein]]s and other [[hydrophobic]] substances. This is why oil and water, famously, do not mix. [[Cell membrane]]s take advantage of this property to carefully control interactions between their contents and external chemicals, which is facilitated somewhat by the surface tension of water.

Water has a high surface tension caused by the strong [[Cohesion (chemistry)|cohesion]] between water molecules. This can be seen when small quantities of water are put onto a nonsoluble surface such as [[polythene]]: the water stays together as drops. On extremely clean [[glass]] the water may form a thin film because the molecular forces between glass and water molecules (adhesive forces) are stronger than the cohesive forces.

In biological cells and [[organelle]]s, water is in contact with membrane and protein surfaces that are [[hydrophilic]], that is, surfaces that have a strong attraction to water. [[Irving Langmuir]] observed a strong repulsive force between hydrophilic surfaces. To dehydrate hydrophilic surfaces—to remove the strongly held layers of water of hydration—requires doing substantial work against these forces, called hydration forces. These forces are very large, but decrease rapidly over a nanometer or less. Their importance in biology has been extensively studied by [[Parsegian]]. They are particularly important when cells are dehydrated by exposure to dry atmospheres or to extracellular freezing.

A simple but environmentally important and unique property of water is that its common solid form, [[ice]], floats on its liquid form. This solid phase is less dense than liquid water, due to the geometry of the strong hydrogen bonds which are formed only at lower temperatures. For almost all other substances and for all other 11 uncommon phases of water ice except ice-XI, the solid form is more dense than the liquid form. Fresh water at standard atmospheric pressure is most dense at 4 °C, and will sink by [[convection]] as it cools to that temperature, and if it becomes colder it will rise instead. This reversal will cause deep water to remain warmer than shallower freezing water, so that ice in a body of water will form first at the surface and progress downward, while the majority of the water underneath will hold a constant 4 °C. This effectively insulates a lake floor from the cold. While this behavior may seem obvious, even intuitive, it should be noted that almost all other chemicals are denser as solids than they are as liquids, and freeze from the bottom up.

A common misconception about water is that it is a powerful conductor of [[electricity]], with risks of [[electric shock|electrocution]] explaining this popular belief. Any electrical properties observable in water are due to the [[ion]]s of mineral salts and [[carbon dioxide]] dissolved in it. [[Self-ionization of water|Water does self-ionize]] where two water molecules become one [[hydroxide]] anion and one [[hydronium]] cation, but not enough to carry enough [[electric current]] to do any work or harm for most operations. Pure water can also be [[electrolysis|electrolized]] into oxygen and hydrogen gases but without any dissolved ions, this is a very slow process and thus very little current is conducted. Many [[bottled water]] companies exploit another common misconception, advertising both [[purity]] and [[taste]], even though pure water is tasteless.

Civilization has historically flourished around rivers and major waterways; [[Mesopotamia]], the so-called cradle of civilization, is situated between two major rivers. Large metropolises like [[London]], [[Paris]], [[New York]], and [[Tokyo]] owe their success in part to their easy accessibility via water and the resultant expansion of trade. Islands with safe water ports, like [[Singapore]] and [[Hong Kong]], have flourished for precisely this reason. In places such as [[North Africa]] and the [[Middle East]], where water is scarcer, access to clean drinking water was and is a major factor in human development.

== Astronomical position of Earth and impact on its water ==
[[Image:Water droplet blue bg05.jpg|thumb|250px|Impact of water]]

Scientists theorize that most of the universe's water is produced as a byproduct of star formation. Gary Melnick, a scientist at the [[Harvard-Smithsonian Center for Astrophysics]], explains: "For reasons that aren't entirely understood, when stars are born, their birth is accompanied by a strong outward wind of gas and dust. When this outflowing material eventually impacts the surrounding gas, the shock waves that are created compress and heat the gas. The water we observe is rapidly produced in this warm dense gas." <ref> {{cite news | title=Discover of Water Vapor Near Orion Nebula Suggests Possible Origin of H20 in Solar System | publisher=The Harvard University Gazette | date=April 23, 1998 | url=http://www.news.harvard.edu/gazette/1998/04.23/DiscoverofWater.html}} </ref>

The coexistence of the solid, liquid, and gaseous phases of water on Earth is vital to existence of life on Earth. However, if the Earth's location in the [[solar system]] were even marginally closer or further from the [[Sun]] (ie, a million miles or so), the conditions which allow the three forms to be present simultaneously would be far less likely to exist.

Earth's mass allows [[gravity]] to hold an [[Celestial body atmosphere|atmosphere]]. [[Water vapor]] and [[carbon dioxide]] in the atmosphere provide a [[greenhouse effect]] which helps maintain a relatively steady surface temperature. If Earth were less massive, a thinner atmosphere would cause temperature extremes preventing the accumulation of water except in [[polar ice cap]]s (as on [[Mars (planet)|Mars]]).

The distance between Earth and the Sun, the combination of solar radiation received and the greenhouse effect of the atmosphere ensure that Earth's surface is neither too cold nor too hot for liquid water. If Earth were more distant from the Sun, most water would be frozen. If Earth were nearer to the Sun, its higher surface temperature would limit the formation of ice caps, or cause water to exist only as vapor.

It has been proposed that life itself may maintain the conditions that have allowed its continued existence. The surface temperature of Earth has been relatively constant through [[geologic time]] despite varying levels of incoming solar radiation ([[insolation]]), indicating that a dynamic process governs Earth's temperature via a combination of greenhouse gases and surface or atmospheric [[albedo]]. This proposal is known as the ''[[Gaia hypothesis]]''.

== Human uses of water ==
[[Image:Sprinkler03.jpg|thumb|250px|left|Water pressure in a sprinkler]]

All known forms of life depend on water. (Note however that some [[bacterium|bacteria]] and plant seeds can enter a [[cryptobiotic state]] for an indefinite period when dehydrated, and "come back to life" when returned to a wet environment). Water is a vital part of many [[metabolism|metabolic]] processes within the body, and significant quantities of water are used during the [[digestion]] of food.

About 72% of the fat free mass of the [[human]] body is made of water. To function properly the body requires between one and seven [[liter]]s of water per [[day]] to avoid [[dehydration]], the precise amount depending on the level of activity, temperature, humidity, and other factors. However, most of this is ingested through other foods or beverages (hot tea being often used in deserts to avoid dehydration, etc.) It is not clear how much water intake is needed by healthy people. However, for those who do not have kidney problems, it is rather difficult to drink too much water, but (especially in warm humid weather and while exercising) dangerous to drink too little. People can drink far more water than necessary while exercising, however, putting them at risk of [[water intoxication]], which can be fatal. The "fact" that a person should consume eight glasses of water per day cannot be traced back to a scientific source <ref> [http://ajpregu.physiology.org/cgi/content/full/283/5/R993 "Drink at least eight glasses of water a day." Really? Is there scientific evidence for "8 × 8"?] by Heinz Valdin, Department of Physiology, Dartmouth Medical School, Lebanon, [[New Hampshire]] </ref>. There are other myths such as the effect of water on weight loss and constipation that have been dispelled <ref> [http://www.factsmart.org/h2o/h2o.htm Drinking Water - How Much?], Factsmart.org web site and references within </ref>.
[[Image:TapWater-china.JPG|thumb|right|150px|A manual water [[pump]] in [[China]].]] The latest dietary reference intake report by the US [[National Research Council]] recommended 2.7 liters of water total (including food sources) for women and 3.7 liters for men <ref> [http://www.iom.edu/report.asp?id=18495 Dietary Reference Intakes: Water, Potassium, Sodium, Chloride, and Sulfate], Food and Nutrition Board</ref>. Water is lost from the body in [[urine]] and [[feces]], through [[sweat]]ing, and by exhalation of [[water vapor]] in the breath.

Humans require water that does not contain too much salt or other impurities. Common impurities include chemicals and/or harmful [[bacterium|bacteria]], such as [[Vibrio]]. Some solutes are acceptable and even desirable for perceived taste enhancement and to provide needed [[electrolytes]].

===Water as a precious resource: politics of water ===
:''See [[water resources]] for information about [[fresh water]] supplies; see also [[:Category:Water and politics|Category:Water and politics]] for articles treating about water politics''
[[Image:Evstafiev-bosnia-sarajevo-water-line.jpg|thumb|People queue to gather water during the [[Siege of Sarajevo]].]]

Because of the growth of [[world population]], [[consumption|mass consumption]] and [[pollution]], the availability of [[drinking water]] [[per capita]] is shrinking. For this reason, water is a strategic resource in the globe, and an important element in many political conflicts. Some have predicted that clean water will become the "next oil", making [[Canada]], with this resource in abundance, possibly the richest country in the world. There is a long history of conflict over water, including efforts to gain access to water, the use of water in wars started for other reasons, and tensions over shortages and control <ref> [http://www.worldwater.org/conflict.html A Chronology of Water-Related Conflicts] </ref>. [[UNESCO]]'s World Water Development Report (WWDR, 2003) from its [[World Water Assessment Program]] indicates that, in the next 20 years, the quantity of water available to everyone is predicted to decrease by 30%. 40% of the world's inhabitants currently have insufficient fresh water for minimal [[hygiene]]. More than 2.2 million people died in [[2000]] from [[disease]]s related to the consumption of contaminated water or [[drought]]. In 2004, the UK charity [[WaterAid]] reported that a child dies every 15 seconds due to easily preventable water-related diseases. Fresh water, now more precious than ever in our history for its extensive use in agriculture, high-tech manufacturing, and energy production, is increasingly receiving attention as a resource requiring better management and sustainable use.

==== Water in the OECD countries ====
With nearly 2,000 [[cubic metres]] of water per person and per year, the [[United States]] leads the world in water consumption per capita (a large quantity of [[Golf#Environmental impact|golf fields]] and [[car washing]] partly explain this massive consumption). In the Organisation for Economic Co-operation and Development ([[OECD]]) countries, the U.S. comes first for water consumption, then Canada with 1,600 cubic metres of water per person per year, which is about twice the amount of water used by the average person from [[France]], three times as much as the average [[Germany|German]], and almost eight times as much as the average [[Denmark|Dane]]. Since 1980, overall water use in Canada has increased by 25.7%. This is five times higher than the overall OECD increase of 4.5%. In contrast, nine OECD nations were able to decrease their overall water use since 1980 ([[Sweden]], the [[Netherlands]], the United States, the [[United Kingdom]], the [[Czech Republic]], [[Luxembourg]], [[Poland]], [[Finland]] and Denmark) <ref> [http://www.environmentalindicators.com/htdocs/indicators/6wate.htm Water consumption indicator] in the [[OECD]] countries </ref> <ref> {{cite news | title=Golf 'is water hazard' | publisher=BBC News | date=March 17, 2003 | url=http://news.bbc.co.uk/1/hi/sci/tech/2857587.stm}} </ref>.

Ninety-five percent of the United States' fresh water is underground. One crucial source is a huge underground reservoir, the 800-mile (1,300 km) [[Ogallala Aquifer|Ogallala aquifer]] which stretches from [[Texas]] to [[South Dakota]] and waters one fifth of U.S. irrigated land. Formed over millions of years, the Ogallala aquifer has since been cut off from its original natural sources. It is being depleted at a rate of 12 billion cubic metres a year&mdash;amounting to a total depletion to date of a volume equal to the annual flow of 18 [[Colorado River]]s. Some estimates say it will dry up in as little as 25 years. Many farmers in the [[Texan High Plains]], which rely particularly on the underground source, are now turning away from [[irrigated agriculture]] as they become aware of the hazards of overpumping <ref> {{cite news | title=Ogallala aquifer - Water hot spots | publisher=BBC News | date=? | url=http://news.bbc.co.uk/1/shared/spl/hi/world/03/world_forum/water/html/ogallala_aquifer.stm}} </ref>.

In [[Mexico City]], an estimated 40% of the city's water is lost through leaky pipes built at the turn of the century <ref> {{cite news | title=Mexico City - Water hot spots | publisher=BBC News | date=? | url=http://news.bbc.co.uk/1/shared/spl/hi/world/03/world_forum/water/html/mexico_city.stm}} </ref>.

==== Water in the Middle East ====
[[Image:Eau transparente naturelle.JPG|thumb|right|200px|Gold water]]
The [[Middle East]] region has only 1% of the world's fresh water, which is shared between 5% of the world's population. Thus, in this region, water is an important strategic resource. By 2025, it is predicted that the countries of the Arabian peninsula will be using more than double the amount of water naturally available to them <ref> {{cite news | title=Water shortages 'foster terrorism' | publisher=BBC News | date=March 18, 2003 | url=http://news.bbc.co.uk/1/hi/sci/tech/2859937.stm}} </ref>. According to a report by the [[Arab League]], two-thirds of Arab countries have less than 1,000 cubic meters water per person per year, which is considered the limit <ref> "Major aspects of scarce water resources management with reference to the Arab countries", Arab League report published for the International Conference on water gestion and water politics in arid zones, in Amman, Jordan, December 1-3, 1999. Quoted by French journalist [[Christian Chesnot]] in {{cite news | title=Drought in the Middle East | publisher=Monde diplomatique | date=February 2000 | url=http://mondediplo.com/2000/02/08chesnot}} - French original version freely available [http://www.monde-diplomatique.fr/2000/02/CHESNOT/13213.html here]. Compare with the 1,600 cubic meters of water used per person and per year in Canada, for example </ref>.

[[Jordan]], for example, has little water and [[dam]]s in other countries have reduced its available water over the years. The [[1994]] [[Israel-Jordan Treaty of Peace]] stated that Israel would give 50 million cubic meters of water per year to Jordan, which it refused to do in 1999 before backtracking. The 1994 treaty stated that the two countries would cooperate in order to allow Jordan better access to water resources, notably through dams on the [[Yarmouk River]] <ref> See 1994 [[Israel-Jordan Treaty of Peace]], annex II, article II, first paragraph </ref>. Confronted by this lack of water, Jordan is preparing new techniques to use non conventional water resources, such as second-hand use of irrigation water and desalinization techniques, which are very costly and are not yet used. A desalinization project will soon be started in [[Hisban]], south of [[Amman]]. The [[Disi]] [[groundwater]] project, in the south of Jordan, will cost at least $250 million to bring out water. Along with the [[Unity Dam]] on the Yarmouk river, it is one of Jordan's largest strategic projects. Born in 1987, the "Unity Dam" would involve both Jordan and [[Syria]]. This "Unity Dam" still hasn't been implemented because of [[Israel]]'s opposition, Jordan and Syrian conflictual relations and refusal of world investors. However, Jordan's reconciliation with Syria following the death of [[Hussein of Jordan|King Hussein]] would make the project envisionable again <ref name="drought_middle_east"> See [[Christian Chesnot]] in {{cite news | title=Drought in the Middle East | publisher=Monde diplomatique | date=February 2000 | url=http://mondediplo.com/2000/02/08chesnot}} - French original version freely available [http://www.monde-diplomatique.fr/2000/02/CHESNOT/13213.html here]. </ref>.

Both [[Israel]] and Jordan rely on the [[Jordan river]], but Israel controls it, as well as 9/10 of the water resources in the region. Water is also an important issue in the [[Israeli-Palestinian conflict|conflict with the Palestinians]] - indeed, according to former Israeli prime minister [[Ariel Sharon]] quoted by Abel Darwish in the BBC, it was one of the causes of the [[Six-Day War|1967 Six-Day War]]. According to the BBC, "with the [[Tsahal|Israeli army]] in control prohibiting [[Palestine|Palestinians]] from pumping water, and [[Israeli settlements|settlers]] using much more advanced pumping equipment, Palestinians complain of "daily theft" of as much as 80% of their underground water" <ref> {{cite news | title=Analysis: Middle East water wars, by Abel Darwish | publisher=BBC News | date=May 30, 2003 | url=http://news.bbc.co.uk/2/hi/middle_east/2949768.stm}} </ref>. Israelis in the [[West Bank]] use four times as much water as their Palestinian neighbours <ref> {{cite news | title=Israel - water hot spots | publisher=BBC News | date=? | url=http://news.bbc.co.uk/1/shared/spl/hi/world/03/world_forum/water/html/israel.stm}} </ref>. According to the [[World Bank]], 90% of the West Bank's water is used by Israelis <ref name="drought_middle_east" />. Article 40 of the appendix B of the [[September 28]], [[1995]] [[Oslo accords]] stated that "Israel recognizes Palestinians' rights on water in the West Bank".

The Syrian [[Golan]] also provides 770 million cubic meters of water per year to Israel, which represents a third of its annual consumption. The Golan's table water goes to the [[Sea of Galilee]], which is Israel's largest reserve, which is afterward redistributed throughout the country by the [[National Water Carrier]]. Occupied since 1967, the Golan thus represents for Israel a strategic territory because of its water resources. <ref name="drought_middle_east" />. However, the level on the Sea of Galilee has dropped over the years, sparking fears that Israel's main water reservoir will become salinated. On its northern border, Israel threatened military action in [[2002]] when [[Lebanon]] opened a new pumping station taking water from a river feeding the Jordan. To help ease the crisis, Israel has agreed to buy water from Turkey and is investigating building desalination plants <ref> {{cite news | title=Israel - water hot spots | publisher=BBC News | date=? | url=http://news.bbc.co.uk/1/shared/spl/hi/world/03/world_forum/water/html/israel.stm}} </ref>.

On the other hand, [[Iraq]] and [[Syria]] watched with apprehension the construction of the [[Atatürk Dam]] in [[Turkey]] and a projected system of 22 dams on the [[Tigris]] and [[Euphrates]] rivers <ref> {{cite news | title=Turkey - water hot spots | publisher=BBC News | date=? | url=http://news.bbc.co.uk/1/shared/spl/hi/world/03/world_forum/water/html/turkey.stm}} </ref>. According to the BBC, the list of 'water-scarce' countries in the region grew steadily from three in 1955 to eight in 1990 with another seven expected to be added within 20 years, including three [[Nile]] nations (the Nile is shared by nine countries).

==== Water in Asia ====
[[Image:Wasser Neves.jpg|thumb|left|180px|A Mountain Stream]]

In Asia, [[Vietnam]] and [[Cambodia]] are concerned by [[China]]'s and [[Laos]]' attempts to control the flux of water. China is also preparing the [[Three Gorges Dam]] project on the [[Yangtze River]], which would become one of the world's largest dams, causing many social and environmental problems. It also has a project to divert water from the Yangtze to the dwindling [[Yellow river]], which feeds China's most important farming region.

The [[Ganges]] is disputed between [[India]] and [[Bangladesh]]. The water reserves are being quickly depleted and polluted, while the [[glacier]] feeding the sacred [[Hinduism|Hindu]] river is retreating hundreds of feet each year because of [[global warming]] and [[deforestation]] in the [[Himalayas]] causing subsoil streams flowing into the Ganges river to dry up. Downstream, India controls the flow to Bangladesh with the [[Farakka Barrage]], 10 km on the Indian side of the border. Until the late 1990s, India used the barrage to divert the river to [[Calcutta]] to stop the city's port drying up during the dry season. This denied Bangladeshi farmers water and [[silt]], and left the [[Sundarban]] wetlands and [[mangrove]] forests at the river's delta seriously threatened. The two countries have now signed an agreement to share the water more equally. Water quality, however, remains a huge problem, with high levels of [[arsenic]] and untreated sewage in the river water <ref> {{cite news | title=Ganges river - water hot spots | publisher=BBC News | date=? | url=http://news.bbc.co.uk/1/shared/spl/hi/world/03/world_forum/water/html/river_ganges.stm}} </ref>.

==== Privatisation of water companies ====
[[Privatisation]] of water companies has been contested on several occasions, due to bad quality of the water, increasing prices, etc. In [[Bolivia]] for example, the proposed privatization of water companies by the [[IMF]] were met by [[Cochabamba protests of 2000|popular protests in Cochabamba in 2000]], which ousted [[Bechtel]], an American engineering firm based in San Francisco. [[SUEZ]] has started retreating from South America, due to similar protests (in [[Buenos Aires]] in [[Argentina]], as well as in [[Santa Fe, Argentina|Santa Fe]]; in [[Córdoba, Argentina|Córdoba]], consumers took to the streets to protest water rate hikes of as much as 500 percent mandated by Suez). In South and Central America, Suez has water concessions in Argentina, Bolivia, Brazil and Mexico. "Bolivian officials fault Suez for not connecting enough households to water lines as mandated by its contract and for charging as much as $455 a connection, or about three times the average monthly salary of an office clerk", according to the ''[[Mercury News]]'' <ref> {{cite news | title=Bolivia's water wars coming to end under Morales | publisher=Mercury News | date=February 26, 2006 | url=http://www.mercurynews.com/mld/mercurynews/news/world/13969197.htm}} </ref>. [[South Africa]] also made moves to privatize water, provoking an outbreak of cholera killing 200 <ref> {{cite news | title=Water privatisation: ask the experts | publisher=BBC News | date=December 10, 2004 | url=http://news.bbc.co.uk/2/hi/talking_point/2957550.stm}} </ref>.

=== Regulating water distribution ===
Drinking water is often collected at [[spring (water)|springs]], extracted from artificial [[boring]]s in the ground, or [[water well|well]]s. Building more wells in adequate places is thus a possible way to produce more water assuming the [[aquifer]]s can supply an adequate flow. Other water sources are rainwater and river or lake water. This surface water, however, must be [[water purification|purified]] for human consumption. This may involve removal of undissolved substances, dissolved substances and harmful [[microbe]]s. Popular methods are [[filtering]] with sand which only removes undissolved material while [[chlorination]] and [[boiling]] kill harmful microbes. [[Distillation]] does all three functions. More advanced techniques exist, such as [[reverse osmosis]]. [[Desalination]] of abundant [[ocean]] or [[seawater]] is a more expensive solution used in coastal [[arid]] [[climate]]s.

The distribution of drinking water is done through [[municipal water system]]s or as [[bottled water]]. Governments in many countries have programs to distribute water to the needy at no charge. Others argue that the [[market]] mechanism and [[free enterprise]] are best to manage this rare resource, and to finance the boring of wells or the construction of dams and [[reservoir (water)|reservoirs]].

Reducing waste, that is using drinking water only for human consumption, is another option. In some cities, such as [[Hong Kong]], sea water is extensively used for flushing toilets citywide in order to conserve fresh water resources. [[Water pollution|Polluting water]] may be the biggest single misuse of water; to the extent that a pollutant limits other uses of the water, it becomes a waste of the resource, regardless of benefits to the pollutor. As other types of pollution, this doesn't enter standard accounting of market costs, being conceived as [[externality|externalities]] for which the market can't account for. Thus other people pay the price of this water pollution, while the private firms' profits are not redistributed to the local population victim of this pollution. [[Pharmaceuticals]] consumed by humans often end up in the waterways and can have detrimental effects on [[aquatic]] life if they [[bioaccumulation|bioaccumulate]] and if they are not [[biodegradable]].

==The impact of water on religion and philosophy==
[[Image:Glass-of-water.jpg|thumb|120px|The proverbial [[Is the glass half empty or half full|glass half empty/full]].]]

Water is considered a purifier in most religions, including [[Hinduism]], [[Christianity]], [[Islam]], [[Judaism]], and [[Shinto]]. For instance, [[baptism]] in Christian churches is done with water. In addition, a ritual bath in pure water is performed for the dead in many religions including Judaism and Islam. In Islam, the five daily prayers can only be done after completing washing the body with clean water ([[wudu]]). In [[Shinto]], water is used in almost all rituals to cleanse a person or an area. Water is mentioned in the [[Bible]] 442 times in the [[New International Version]] and 363 times in the [[King James Version]]. 2 Peter 3:5(b) states: ..."the earth was formed out of water and by water." (NIV)

Water is often believed to have spiritual powers. In [[Celtic mythology]], [[Sulis]] is the local [[goddess]] of thermal springs; in [[Hinduism]], the [[Ganga]] is also personified as a goddess, while [[Saraswati]] have been referred to as goddess in [[Veda]]s. Also water is one of the "panch-tatva"s (basic 5 elements, others including [[Fire]], [[Earth]], [[Space]], [[Air]]). Alternatively, gods can be patrons of particular springs, river or lakes: for example in [[Greek mythology|Greek]] and [[Roman mythology|Roman]] [[mythology]], [[Peneus]] was a river god, one of the three thousand [[Oceanids]].

The [[Ancient Greece|Greek]] [[philosopher]] [[Empedocles]] held that water is one of the four [[classical element]]s along with [[fire]], [[earth]] and [[Air (classical element)|air]], and was regarded as the [[ylem]], or basic stuff of the universe. Water was considered cold and moist. In the theory of the four [[bodily humour]]s, water was associated with [[phlegm]]. [[Water (classical element)|Water]] was also one of the [[Five Elements]] in traditional [[Chinese philosophy]], along with [[earth (classical element)|earth]], [[fire (classical element)|fire]], [[wood (classical element)|wood]], and [[metal (classical element)|metal]].

Water can also come in many different colours, such as red, green, purple, brown, blue, grey, black, and it can also smell like cheese.

== Notes ==
<!-- See [[Wikipedia:footnotes]] -->
<references/>

== See also ==
[[Image:Photo of two people reflected in a fish pond.JPG|right|thumb|255px|Two people [[reflection (physics)|reflected]] in the water of a [[fish pond]] ]]
* [[Atmospheric water generator]]
* [[Air to Water Harvest]]
* [[Dehydration]] (hypohydration) vs. [[hyperhydration]]
* [[Desalination]]
* [[Dihydrogen monoxide hoax]]
* [[Distilled water]]
* [[Double distilled water]]
* [[Drought]]
* [[Ecohydrology]]
* [[Evapotranspiration]]
* [[Flood]]
* [[Flume]]
* [[Fountain]]
* [[Fresh water]]
* [[Heavy water]]
* [[Holy water]]
* [[Hydrography]]
* [[Hydrology]]
* [[Hydrosphere]]
* [[Irrigation]]
* [[Mineral water]]
* [[Origin of water on Earth]]
* [[Pond]]
* [[Precipitation (meteorology)]]
* [[Rain]]
* [[Safe water]]
* [[Sea water]]
* [[Spring water]]
* [[Tide]]
* [[Transvasement]]
* [[VSMOW|Vienna Standard Mean Ocean Water]]
* [[Wastewater]]
* [[WaterAid]]
* [[Water Air Extraction Devices]]
* [[Water (data page)]]
* [[Water (molecule)]]
* [[Water industry]]
* [[Water intoxication]]
* [[Water ionizer]]
* [[Water memory]]
* [[Water park]]
* [[Water purification]]
* [[Water quality]]
* [[Water quality modelling]]
* [[Water resources]]
* [[Water tank]]
* [[Water therapy]]
* [[Water torture]]
* [[World Ocean Day]]
* [[World Water Day]]

== References ==
* OA Jones, JN Lester and N Voulvoulis, Pharmaceuticals: a threat to drinking water? ''TRENDS in Biotechnology'' 23(4): 163, 2005
* Franks, F (Ed), Water, A comprehensive treatise, Plenum Press, New York, 1972-1982
* [http://twt.mpei.ac.ru/mas/worksheets/VTP_wsp.mcd Property of Water and Water Steam w Thermodynamic Surface]
* PH Gleick and associates, The World's Water: The Biennial Report on Freshwater Resources. Island Press, Washington, D.C. (published every two years, beginning in 1998.)

=== Water as a natural resource ===
*{{cite book | title=The World's Water: The Biennial Report on Freshwater Resources | first=Peter H. | last=Gleick | location=Washington | publisher=Island Press}} (Produced every two years; [http://www.worldwater.org data available here])
*{{cite book | title=Last Oasis: Facing Water Scarcity | year=1997, second edition| first=Sandra | last=Postel | location=New York | publisher=Norton Press}}
*{{cite book | title=Water Rights: Scarce Resource Allocation, Bureaucracy, and the Environment | year=1991| author=Anderson}}
*{{cite book | title=Water: The Fate of Our Most Precious Resource | year=2003, revised edition| author=Marq de Villiers}}
*{{cite book | title=Water Wars: Drought, Flood, Folly and the Politics of Thirst | year=2002 | author=Diane Raines Ward}}
*{{cite book | title=Water and Power: The Politics of a Scarce Resource in the Jordan River Basin | year=1995| author=Miriam R. Lowi}} (Cambridge Middle East Library)
*{{cite book | title=Rivers of Empire: Water, Aridity, and the Growth of the American West | year=1992 | first=Donald | last=Worster}}
*{{cite book | title=Cadillac Desert: The American West and Its Disappearing Water | year=1993 | first=Marc | last=Reisner}}
*{{cite book | title=Blue Gold: The Fight to Stop the Corporate Theft of the World's Water | author=Maude Barlow, Tony Clarke | year=2003}}
*{{cite book | title=Water Wars: Privatization, Pollution, and Profit | author=Vandana Shiva | year=2002 | id=ISBN 0745318371}}
*{{cite book | title=Troubled Water: Saints, Sinners, Truth And Lies About The Global Water Crisis | author=Anita Roddick, et al | year=2004}}

==External links==
{{commons|water}}
{{wiktionary}}
* [http://www.unesco.org/water/wwap/ UNESCO's World Water Assessment Program]
* [http://www.unesco.org/water/ UNESCO Water Portal]
* [http://www.unesco-ihe.org/ UNESCO-IHE Institute for Water Education]
* [http://unesdoc.unesco.org/images/0012/001295/129556e.pdf United Nations' World Water Development Report]
* [http://www.gemswater.org/ United Nations GEMS/Water Programme]
* [http://www.worldwater.org The World's Water, data, historical information on conflict]
* [http://www.lsbu.ac.uk/water/phase.html Phase diagrams of water]
* [http://www.publicforuminstitute.org/issues/oceans/index.htm Oceans and Water Issues Page]
* [http://www.greenfacts.org/water-disinfectants/index.htm Scientific Facts on Water Disinfectants] A faithful summary by GreenFacts of a leading scientific consensus report on Drinking Water Disinfectants published by the International Programme on Chemical Safety of the WHO.
* [http://www.hkc22.com/residentialwater.html Residential water problems and markets] Study paper from Helmut Kaiser Consultancy
* [http://www.hkc22.com/watermarketsworldwide.html Water markets worldwide] Study paper from Helmut Kaiser Consultancy
* [http://www.worldwaterforum.org/ World Water Forum]
* [http://www.lsbu.ac.uk/water/ Water Structure and Behaviour]
* [http://www.wateraid.org/ WaterAid]
* [http://www.sahra.arizona.edu/newswatch/ SAHRA&mdash;Global Water Newswatch]
* [http://www.siwi.org/ Stockholm International Water Institute] (SIWI)
* [http://www.c-win.org/ California Water Impact Network (C-WIN)]
* [http://news.bbc.co.uk/2/hi/science/nature/3752590.stm BBC: The water debate]
* [http://news.bbc.co.uk/2/hi/in_depth/world/2003/world_forum/water/default.stm BBC News (International): The Water Debate]
* [http://ca.geocities.com/tapvsbottled/ Tap Water Vs Bottled Water] - Interesting site providing facts about tap and bottled water.
* [http://www.emagazine.com/september-october_2003/0903feat1.html ''E the Environmental Magazine'' piece on bottled water] (Oct 2003).
* [http://www.iapws.org/ International Association for the Properties of Water and Steam]
* [http://ga.water.usgs.gov/edu/watercycle.html US Geological Survey: Comprehensive discussion of the water cycle, in many languages]
* [http://www.dartmouth.edu/~etrnsfer/water.htm Why is water blue?]
* [http://www.water.org.uk/home/resources-and-links/water-for-health/ask-about/adults Water requirements in adults]
* [http://www.hkc22.com/environmentaltechnology.html/ Climate change raises markets for environmental technology, drinking water and clean energies]
* [http://www.phys.unsw.edu.au/~jw/unfreezable.html 'Unfreezable water', bound water and water of hydration]
* [http://encarta.msn.com/media_461541579/Phase_Diagram_for_Water.html MSN Encarta - Multimedia - Phase Diagram for Water]

[[Category:Water| ]]
[[Category:Natural resources]]

{{Link FA|ar}}
{{Link FA|he}}

[[als:Wasser]]
[[ar:ماء]]
[[bg:Вода]]
[[bn:জল]]
[[ca:Aigua]]
[[cs:Voda]]
[[cy:Dŵr]]
[[da:Vand]]
[[de:Wasser]]
[[el:Νερό]]
[[eo:Akvo]]
[[es:Agua]]
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[[eu:Ur]]
[[fi:Vesi]]
[[fr:Eau]]
[[ga:Uisce]]
[[gl:Auga]]
[[he:מים]]
[[hi:पानी]]
[[hr:Voda]]
[[hu:Víz]]
[[id:Air]]
[[io:Aquo]]
[[is:Vatn]]
[[it:Acqua]]
[[ja:水]]
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[[ru:Вода]]
[[simple:Water]]
[[sk:Voda]]
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[[su:Cai]]
[[sv:Vatten]]
[[ta:நீர்]]
[[th:น้ำ]]
[[tl:Tubig]]
[[tr:Su]]
[[uk:Вода]]
[[vi:Nước]]
[[vo:Vat]]
[[zh:水]]
[[zh-min-nan:Chúi]]
[[zh-yue:水]]

Revision as of 13:12, 4 May 2006

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