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Drinking water

2007 Schools Wikipedia Selection. Related subjects: Drink

   Drinking water
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   Drinking water is water that is intended to be ingested by humans.
   Water of sufficient quality to serve as drinking water is termed
   potable water whether it is used as such or not. Although many fresh
   water sources are utilised by humans, some contain disease vectors or
   pathogens and cause long-term health problems if they do not meet
   certain water quality guidelines. Water that is not harmful for human
   beings is sometimes called safe water, water which is not contaminated
   to the extent of being unhealthful. The available supply of drinking
   water is an important criterion of carrying capacity, the population
   level that can be supported by planet Earth.

   As of the year 2006 (and pre-existing for at least three decades),
   there is a substantial shortfall in availability of potable water,
   primarily arising from overpopulation in lesser developed countries. As
   of the year 2000, 37 percent of the populations of lesser developed
   countries did not have access to safe drinking water. Implications for
   disease propagation are significant. Many nations have water quality
   regulations for water sold as drinking water, although these are often
   not strictly enforced outside of the developed world. The World Health
   Organization sets international standards for drinking water. A broad
   classification of drinking water safety worldwide could be found in
   Safe Water for International Travelers.

   Typically water supply networks deliver a single quality of water,
   whether it is to be used for drinking, washing or landscape irrigation;
   one counterexample is urban China, where drinking water can be
   optionally delivered by a separate tap. In the United States, public
   drinking water is governed by the Safe Drinking Water Act (SDWA). Among
   other provisions, it protects the right of employees to report
   potential violations. 42 U.S.C. 300j-9(i). Within 30 days of any
   retaliation, a whistleblower can file a complaint with the Occupational
   Safety and Health Administration (OSHA).

   The standard test for bacterial contamination is a laboratory analysis
   of coliform bacteria, a convenient marker for a class of harmful fecal
   pathogens. The presence of fecal coliforms (like Escherichia coli)
   serves as an indication of contamination by sewage.

Global availability

   Due to the presence of overpopulation, which has been prevalent as
   early as 1975, adequate water resources do not exist to provide safe
   drinking water for all people. The issue of overpopulation is
   compounded by the realities of wealth distribution and regional
   differences in fresh water storage capacity. Africa has been the first
   region to suffer pronounced widespread inadequate potable water, but by
   around 2015, Asia will certainly own the distinction of greatest water
   shortfall, due to the expanding population of the continent.

   According to the United Nations over 1.1 billion people are currently
   without safe drinking water. In highly developed countries such as
   Singapore, United Kingdom, Australia, USA, Sweden, Denmark, Andorra,
   Finland, Canada and Mauritius, virtually 100 % of the populations have
   access to potable water. The majority of the people in the world who
   have unsafe water are concentrated in a few large countries including
   China, India, Pakistan, Nigeria, Indonesia and Bangladesh. The
   availability and universal access to safe drinking water to the
   populations in several more countries is listed below.
     * Albania (97%)
     * Algeria (89%)
     * Azerbaijan (78%)
     * Brazil (87%)
     * Chile (93%)
     * Cuba (91%)
     * Egypt (97%)
     * Iraq (85%)
     * Iran (92%)
     * Mexico (88%)
     * Morocco (80%)
     * Peru (80%)
     * Syria (80%)
     * Sudan (67%)
     * South Africa (86%)
     * Turkey (82%)
     * Tunisia (80%)
     * Venezuela (83%)
     * Zimbabwe (83%)

Metabolism

   Water is essential for all life on Earth, including mammals and
   mankind. Humans can survive for several weeks without food, but for
   only a few days without water. A constant supply is needed to replenish
   the fluids lost through normal physiological activities, such as
   respiration, sweating and urination. Water generated from the
   biochemical metabolism of nutrients provides a significant proportion
   of the daily water requirements for some arthropods and desert animals,
   although it provides only a small fraction for humans. There are a
   variety of trace elements present in virtually all potable water, some
   of which play a role in metabolism; for example sodium, potassium and
   chloride are common chemicals found in very small amounts in most
   waters, and these elements play a role (not necessarily major) in body
   metabolism. Other elements such as fluoride, while beneficial in low
   concentrations, can cause dental problems and other issues when present
   at high levels.

   Retrieved from " http://en.wikipedia.org/wiki/Drinking_water"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
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