Drinking Water
<p ><b>Drinking water</b> or <b>potable water</b> is <a href="http://en.wikipedia.org/wiki/Water" title="Water" >water</a> safe enough to be consumed by humans or used with low risk of immediate or long term harm. In most <a href="http://en.wikipedia.org/wiki/Developed_country" title="Developed country" >developed countries</a>, the water supplied to households, commerce and industry meets drinking water standards, even though only a very small proportion is actually consumed or used in food preparation. Typical uses (for other than potable purposes) include toilet flushing, washing and <a href="http://en.wikipedia.org/wiki/Landscape" title="Landscape" >landscape</a><a href="http://en.wikipedia.org/wiki/Irrigation" title="Irrigation" >irrigation</a>.
Over large parts of the world, humans have inadequate access to potable water and use sources contaminated with <a href="http://en.wikipedia.org/wiki/Disease_vector" title="Disease vector" class="mw-redirect" >disease vectors</a>,<a href="http://en.wikipedia.org/wiki/Pathogen" title="Pathogen" >pathogens</a> or unacceptable levels of toxins or suspended solids. Drinking or using such water in food preparation leads to widespread acute and chronic illnesses and is a major cause of death and misery in many countries. Reduction of <a href="http://en.wikipedia.org/wiki/Waterborne_diseases" title="Waterborne diseases" >waterborne diseases</a> is a major <a href="http://en.wikipedia.org/wiki/Public_health" title="Public health" >public health</a> goal in developing countries.
Water has always been an important and life-sustaining drink to humans and is essential to the survival of all known organisms.<sup id="cite_ref-bbc_0-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Potable_water#cite_note-bbc-0" >[1]</a></sup>Excluding <a href="http://en.wikipedia.org/wiki/Fat" title="Fat" >fat</a>, water composes approximately 70% of the <a href="http://en.wikipedia.org/wiki/Human_body" title="Human body" >human body</a> by mass. It is a crucial component of <a href="http://en.wikipedia.org/wiki/Metabolic" title="Metabolic" class="mw-redirect" >metabolic</a> processes and serves as a <a href="http://en.wikipedia.org/wiki/Solvent" title="Solvent" >solvent</a> for many bodily <a href="http://en.wikipedia.org/wiki/Solutes" title="Solutes" class="mw-redirect" >solutes</a>. The <a href="http://en.wikipedia.org/wiki/United_States_Environmental_Protection_Agency" title="United States Environmental Protection Agency" >United States Environmental Protection Agency</a> in risk assessment calculations assumes that the average American adult ingests 2.0 litres per day.<sup id="cite_ref-epa_1-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Potable_water#cite_note-epa-1" >[2]</a></sup> Drinking water of a variety of qualities is bottled. <a href="http://en.wikipedia.org/wiki/Bottled_water" title="Bottled water" >Bottled water</a> is sold for public consumption throughout the world.</p>
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Some health authorities have suggested that people drink at least eight glasses, eight <a href="http://en.wikipedia.org/wiki/Fl_oz" title="Fl oz" class="mw-redirect" >fl oz</a> each (240 mL), of water per day (64 fl oz, or 1.89 <a href="http://en.wikipedia.org/wiki/Litre" title="Litre" >litres</a>),<sup id="cite_ref-epa_1-1" class="reference" ><a href="http://en.wikipedia.org/wiki/Potable_water#cite_note-epa-1" >[2]</a></sup><sup id="cite_ref-2" class="reference" ><a href="http://en.wikipedia.org/wiki/Potable_water#cite_note-2" >[3]</a></sup> and the <a href="http://en.wikipedia.org/wiki/British_Dietetic_Association" title="British Dietetic Association" >British Dietetic Association</a>recommends 1.8 litres.<sup id="cite_ref-bbc_0-1" class="reference" ><a href="http://en.wikipedia.org/wiki/Potable_water#cite_note-bbc-0" >[1]</a></sup> This common misconception is not supported by scientific research. Various reviews of all the scientific literature on the topic performed in 2002 and 2008 could not find any solid scientific evidence that recommended drinking eight glasses of water per day.<sup id="cite_ref-3" class="reference" ><a href="http://en.wikipedia.org/wiki/Potable_water#cite_note-3" >[4]</a></sup><sup id="cite_ref-4" class="reference" ><a href="http://en.wikipedia.org/wiki/Potable_water#cite_note-4" >[5]</a></sup><sup id="cite_ref-5" class="reference" ><a href="http://en.wikipedia.org/wiki/Potable_water#cite_note-5" >[6]</a></sup> In the US, the <a href="http://en.wikipedia.org/wiki/Reference_Daily_Intake" title="Reference Daily Intake" >reference daily intake</a> (RDI) for water is 3.7 litres per day (L/day) for human males older than 18, and 2.7 L/day for human females older than 18<sup id="cite_ref-6" class="reference" ><a href="http://en.wikipedia.org/wiki/Potable_water#cite_note-6" >[7]</a></sup>including water contained in food, beverages, and drinking water. The amount of water varies with the individual, as it depends on the condition of the subject, the amount of physical exercise, and on the environmental temperature and humidity.<sup id="cite_ref-7" class="reference" ><a href="http://en.wikipedia.org/wiki/Potable_water#cite_note-7" >[8]</a></sup> An individual's thirst provides a better guide for how much water they require rather than a specific, fixed quantity.<sup class="Template-Fact" >[<i><a href="http://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed" >citation needed</a></i>]</sup>
In terms of mineral nutrients intake, it is unclear what the drinking water contribution is. <a href="http://en.wikipedia.org/wiki/Inorganic_compound" title="Inorganic compound" >Inorganic</a> minerals generally enter surface water and ground water via <a href="http://en.wikipedia.org/wiki/Stormwater" title="Stormwater" >storm water</a> <a href="http://en.wikipedia.org/wiki/Surface_runoff" title="Surface runoff" >runoff</a> or through the Earth's crust. Treatment processes also lead to the presence of some minerals. Examples include <a href="http://en.wikipedia.org/wiki/Calcium" title="Calcium" >calcium</a>,<a href="http://en.wikipedia.org/wiki/Zinc" title="Zinc" >zinc</a>, <a href="http://en.wikipedia.org/wiki/Manganese" title="Manganese" >manganese</a>, <a href="http://en.wikipedia.org/wiki/Phosphate" title="Phosphate" >phosphate</a>, <a href="http://en.wikipedia.org/wiki/Fluoride" title="Fluoride" >fluoride</a> and <a href="http://en.wikipedia.org/wiki/Sodium" title="Sodium" >sodium</a> compounds.<sup id="cite_ref-8" class="reference" ><a href="http://en.wikipedia.org/wiki/Potable_water#cite_note-8" >[9]</a></sup> Water generated from the <a href="http://en.wikipedia.org/wiki/Biochemistry" title="Biochemistry" >biochemical</a><a href="http://en.wikipedia.org/wiki/Metabolism" title="Metabolism" >metabolism</a> of nutrients provides a significant proportion of the daily water requirements for some <a href="http://en.wikipedia.org/wiki/Arthropod" title="Arthropod" >arthropods</a>and <a href="http://en.wikipedia.org/wiki/Desert" title="Desert" >desert</a> animals, but provides only a small fraction of a human's necessary intake. There are a variety of trace elements present in virtually all potable water, some of which play a role in metabolism. For example sodium, <a href="http://en.wikipedia.org/wiki/Potassium" title="Potassium" >potassium</a> and <a href="http://en.wikipedia.org/wiki/Chloride" title="Chloride" >chloride</a> are common chemicals found in small quantities in most waters, and these elements play a role (not necessarily major) in body metabolism. </p>
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Other elements such as <a href="http://en.wikipedia.org/wiki/Fluoride" title="Fluoride" >fluoride</a>, while beneficial in low concentrations, can cause dental problems and other issues when present at high levels. Water is essential for the growth and maintenance of our bodies, as it is involved in a number of biological processes.
Profuse sweating can increase the need for <a href="http://en.wikipedia.org/wiki/Electrolyte" title="Electrolyte" >electrolyte</a> (salt) replacement. <a href="http://en.wikipedia.org/wiki/Water_intoxication" title="Water intoxication" >Water intoxication</a> (which results in <a href="http://en.wikipedia.org/wiki/Hyponatremia" title="Hyponatremia" >hyponatremia</a>), the process of consuming too much water too quickly, can be fatal.<sup id="cite_ref-9" class="reference" ><a href="http://en.wikipedia.org/wiki/Potable_water#cite_note-9" >[10]</a></sup><sup id="cite_ref-10" class="reference" ><a href="http://en.wikipedia.org/wiki/Potable_water#cite_note-10" >[11]</a></sup></p>