Drinking Water

Drinking water is potable water or water that can be drunk or ingested by human beings. Water is a vital necessity for humans, without which they quickly die.

The modern world is now rapidly growing more urban than rural and has a population projected to reach as high as 12 billion people by the year 2050. Securing potable water for all people is challenging the limited supplies.

Although almost 70 percent of the surface of the Earth is covered by water in the world's oceans and seas its saline content is too high for humans to drink. In addition, enormous amounts of water are locked [Page 557]in ice caps in Antarctica, Greenland, and elsewhere. Other large quantities exist as water vapor in clouds or in the atmosphere. As a consequence, only about one or two percent of the water on the surface of the earth is fresh water available to people for drinking.

Virtually all of the water that people drink begins as rain water. It is gathered by nature and is available in very unevenly distributed places. As a result, drinking water comes from the surface of the Earth or from relatively shallow sources underground. The most common natural water sources for potable water are springs, lakes, streams, rivers, rain collectors, underground aquifers, or other natural sources.

The fresh water supplies needed as drinking water are competed for by agricultural, industrial, and recreational users. In addition, it is simply not possible to sustain the ecology if all of the waters of lakes and streams are diverted for human use. As a consequence, much of the water drunk by people in urban areas is purified water. This is water that may have been used previously for industry, sewage, agricultural runoff, or other polluting and toxic uses. However, the science of water purification is advanced to the level where water can be used and then purified as is moves down stream to the sea in city after city.

The use of purification systems would be required even if the water supplies were not polluted by prior human use. There are a variety of diseases that come from microbes in water such as E. coli or typhoid that would imperil human health without purification. Modern water purification uses chemicals to purify the water people drink. Chlorine or other chemicals are used to kill germs. The use of chlorine or chlorine compounds carries a small risk because it is an element that is a known carcinogen. However, the risk is very small that chlorine may cause cancer versus the very high likelihood that large numbers of people will sicken and die from untreated water.

Innovative ideas offered the sources for new supplies of fresh water have included melting frozen water and in Libya pumping water trapped in earlier geologic eras across the Sahara Desert to population centers. Another important possible source that has been offered is the used of desalination plants that can extract fresh potable water from sea water.

There are currently problems associated with the used of desalination processes. The problems include the high amounts of energy that are required to desalinate water and the quality of the water itself. If it is sterile water, that is just pure evaporated water then it will taste flat and it will also be lacking in minerals that are found in natural water. Strictly speaking, all water on Earth is mineral water. As rain falls, it can collect minerals from the air. When it hits the ground, it will usually absorb some combination of minerals from rocks and soils it passes through.

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