Daily consumption of drinking water
{{Short description|Recommendations for human consumption}}
The recommended daily amount of drinking water for humans varies.{{cite book |chapter-url=https://www.who.int/water_sanitation_health/dwq/nutrientschap3.pdf |title=Water Requirements, Impinging Factors, & Recommended Intakes |author1=Ann C. Grandjean |date=August 2004 |publisher=World Health Organization |pages=25–34 |chapter=3 |archive-url=https://web.archive.org/web/20160222003438/http://www.who.int/water_sanitation_health/dwq/nutrientschap3.pdf |archive-date=22 February 2016 |url-status=live }} This 2004 article focuses on the USA context and uses data collected from the US military. It depends on activity, age, health, and environment. In the United States, the Adequate Intake for total water, based on median intakes, is {{Convert|4.0|L|floz|sigfig=3}} per day for males older than 18, and {{Convert|3.0|L|floz|sigfig=3}} per day for females over 18; it assumes about 80% from drink and 20% from food.{{cite web|title=US daily reference intake values|url=http://iom.edu/Reports/2004/Dietary-Reference-Intakes-Water-Potassium-Sodium-Chloride-and-Sulfate.aspx|url-status=dead|archive-url=https://web.archive.org/web/20111006174858/http://www.iom.edu/Reports/2004/Dietary-Reference-Intakes-Water-Potassium-Sodium-Chloride-and-Sulfate.aspx|archive-date=6 October 2011|access-date=5 December 2011|publisher=Iom.edu}} The European Food Safety Authority recommends {{convert|2.0|L|floz}} of total water per day for women and {{convert|2.5|L|floz}} per day for men.{{cite journal|author=EFSA Panel on Dietetic Products, Nutrition, and Allergies|year=2010|title=Scientific Opinion on Dietary Reference Values for water|journal=EFSA Journal|volume=8|issue=3|page=1459|doi=10.2903/j.efsa.2010.1459|doi-access=free}}
The common advice to drink 8 glasses ({{convert|64|USoz|mL||abbr=on|disp=or|order=flip}}) of plain water per day is not scientific; thirst is a better guide for how much water to drink than is a specific, fixed amount.H. Valtin, [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"?] {{webarchive|url=https://web.archive.org/web/20100420204226/http://ajpregu.physiology.org/cgi/content/full/283/5/R993|date=20 April 2010}} Am J Physiol Regul Integr Comp Physiol 283: R993-R1004, 2002. Americans aged 21 and older, on average, drink {{Convert|1,043|mL|floz|abbr=on}} of drinking water a day, and 95% drink less than {{Convert|2,958|mL|floz|abbr=on}} per day.{{cite book |url=http://www.epa.gov/ncea/efh/pdfs/efh-complete.pdf |title=Exposure Factors Handbook: 2011 Edition |date=September 2011 |publisher=National Center for Environmental Assessment |access-date=24 May 2015 |archive-url=https://web.archive.org/web/20150924093656/http://www.epa.gov/ncea/efh/pdfs/efh-complete.pdf |archive-date=24 September 2015 |url-status=dead }} Exercise and heat exposure cause loss of water and therefore may induce thirst and greater water intake.{{cite web|date=11 February 2004|title=Report Sets Dietary Intake Levels for Water, Salt, and Potassium To Maintain Health and Reduce Chronic Disease Risk|url=http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=10925|access-date=13 September 2017|publisher=US Institute of Medicine, Food and Nutrition Board}} Active people in hot climates may need {{convert|6.0|L|floz|sigfig=3}} of water, or more, per day.
How much drinking water contributes to the intake of mineral nutrients is unclear. Inorganic minerals generally enter surface water and groundwater via stormwater runoff and through the ground. Water treatment also adds some minerals, such as calcium, zinc, manganese, phosphate, fluoride, and sodium compounds.[https://www.who.int/en/ World Health Organization] {{webarchive|url=https://web.archive.org/web/20110119093445/http://www.who.int/en/|date=19 January 2011}} (WHO). Geneva, Switzerland. Joyce Morrissey Donohue, Charles O. Abernathy, Peter Lassovszky, George Hallberg. [https://www.who.int/entity/water_sanitation_health/dwq/nutintakes.pdf "The contribution of drinking-water to total dietary intakes of selected trace mineral nutrients in the United States."] Draft, August 2004. Water generated by the biochemical metabolism of nutrients provides a significant part of the daily water needs for some arthropods and desert animals, but provides only a small fraction of a human's necessary intake. There are trace elements in almost all potable water; some of these affect metabolism, such as sodium, potassium, and chloride, which are common in small amounts in most water. Other elements, such as fluoride, while beneficial in low concentrations, can cause dental and other problems at high levels.
Fluid balance is important to health. Profuse sweating can increase the need to replace electrolytes (salts). Water intoxication (the consumption of too much water too quickly) causes hyponatremia, which can cause death in minutes or hours.{{Cite journal|last1=Noakes|first1=Timothy D.|last2=Goodwin|first2=Neil|last3=Rayner|first3=Brian L.|last4=Branken|first4=Trevor|last5=Taylor|first5=Robert K.N.|date=2005|title=Water Intoxication: A Possible Complication During Endurance Exercise☆|url=https://linkinghub.elsevier.com/retrieve/pii/S1080603205704014|journal=Wilderness & Environmental Medicine|language=en|volume=16|issue=4|pages=221–227|doi=10.1580/1080-6032(2005)16[221:WIAPCD]2.0.CO;2|pmid=16366205 |s2cid=28370290 }} Water makes up about 60% of the body weight in men and 55% of weight in women.{{cite book|last1=Miller|first1=Thomas A.|url=https://books.google.com/books?id=P4lb4XhJJ2UC&pg=PA34|title=Modern surgical care physiologic foundations and clinical applications|date=2006|publisher=Informa Healthcare|isbn=978-1-4200-1658-1|edition=3rd|location=New York|page=34|archive-url=https://web.archive.org/web/20170901014347/https://books.google.com/books?id=P4lb4XhJJ2UC&pg=PA34|archive-date=1 September 2017|url-status=live}} A baby is about 70% to 80%; old people are about 45% water.{{cite book|url=https://books.google.com/books?id=7uk0GJckmy0C&pg=PA340|title=Nancy caroline's emergency care in the streets|date=2012|publisher=Jones And Bartlett Learning|isbn=978-1-4496-4586-1|edition=07|location=[S.l.]|page=340|archive-url=https://web.archive.org/web/20170901014347/https://books.google.com/books?id=7uk0GJckmy0C&pg=PA340|archive-date=1 September 2017|url-status=live}}