Drinking water
2007 Schools Wikipedia Selection. Related subjects: Drink
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.