Distilled water is water that has many of its impurities removed through distillation. Distillation involves boiling the water and then condensing the steam into a clean container. In chemical and biological laboratories, as well as industry, cheaper alternatives such as deionized water are preferred over distilled water. However, if these alternatives are not sufficiently pure, distilled water is used. Where exceptionally high purity water is required, double distilled water is used.
Distilled water is also commonly used to top off lead acid batteries used in cars and trucks. The presence of other ions commonly found in tap water will cause a drastic reduction in an automobile's battery lifespan.
Distilled water is preferable to tap water for use in automotive cooling systems. The minerals and ions typically found in tap water can be corrosive to internal engine components, and can cause a more rapid depletion of the anti-corrosion additives found in most antifreeze formulations.
Distilled water is also preferable to tap water for use in model steam engine boilers and model engines of other types. Mineral build-up resulting from the use of tap water in model boilers can severely reduce the efficiency of the boilers if run for long periods. This build-up is known as boiler scale. Using distilled water in steam irons for pressing clothes can help reduce mineral build-up and make the iron last longer. However, many iron manufacturers say that distilled water is no longer necessary in their irons.
Some people use distilled water for household aquariums because it lacks the chemicals found in tap water supplies. It is important to supplement distilled water when using it for fishkeeping; it is too pure to sustain proper chemistry to support an aquarium ecosystem. Distilled water is also an essential component for use in cigar humidors. Mineral build-up resulting from the use of tap water (including bottled water) will reduce the effectiveness of the humidor.
Drinking distilled water is quite common. Many beverage manufacturers use distilled water to ensure a drink's purity and taste. Bottled distilled water is sold as well, and can usually be found in supermarkets or pharmacies. Water purification, such as distillation, is especially important in regions where water resources or tap water is not suitable for ingesting without boiling or chemical treatment.
Municipal water supplies often add or have trace impurities at levels which are regulated to be safe for consumption. Many of these additional impurities, such as volatile organic compounds, fluoride, and certain other chemical compounds are not removed through conventional filtration; however, distillation can eliminate some of these impurities. Distilled water is also used as drinking water in arid seaside areas which do not have sufficient freshwater, by distilling seawater.
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Thursday, May 26, 2011
Water for Health: Purified Water
Purified water is water from any source that is physically processed to remove impurities. Distilled water and deionized (DI) water have been the most common forms of purified water, but water can also be purified by other processes including reverse osmosis, carbon filtration, microfiltration, ultrafiltration, ultraviolet oxidation, or electrodialysis. In recent decades, a combination of the above processes have come into use to produce water of such high purity that its trace contaminants are measured in parts per billion (ppb) or parts per trillion (ppt). Purified water has many uses, largely in science and engineering laboratories and industries, and is produced in a range of purities. Purified water in colloquial English can also refer to water which has been treated ("rendered potable") to neutralize, but not necessarily remove contaminants considered harmful to humans and/or animals.
Distilled water is often defined as bottled water that has been produced by a process of distillation and has an electrical conductivity of not more than 10 µS/cm and total dissolved solids of less than 10 mg/litre. Distillation involves boiling the water and then condensing the vapour into a clean container, leaving solid contaminants behind. Distillation produces very pure water but also leaves behind a white or yellowish mineral scale on the distillation apparatus, which requires that the apparatus be frequently cleaned. Distillation does not guarantee the absence of bacteria in drinking water; unless the reservoir and/or bottle are sterilized before being filled, and once the bottle has been opened, there is a risk of presence of bacteria.
For many applications, cheaper alternatives such as deionized water are used in place of distilled water.
Double-distilled water is prepared by double distillation of water. Historically, it was the de facto standard for highly purified laboratory water for biochemistry and trace analysis until combination methods of purification became widespread.
Deionization
Deionized water, also known as demineralized water, is water that has had its mineral ions removed, such as cations from sodium, calcium, iron, copper and anions such as chloride and bromide. Deionization is a physical process which uses specially-manufactured ion exchange resins which bind to and filter out the mineral salts from water. Because the majority of water impurities are dissolved salts, deionization produces a high purity water that is generally similar to distilled water, and this process is quick and without scale buildup. However, deionization does not significantly remove uncharged organic molecules, viruses or bacteria, except by incidental trapping in the resin.
Deionization does not remove the hydroxide or hydronium ions from water. These are the products of the self-ionization of water to equilibrium and therefore are impossible to remove.
Other processesOther processes are also used to purify water, including reverse osmosis, carbon filtration, microporous filtration, ultrafiltration, ultraviolet oxidation, or electrodialysis. These are used in place of, or in addition to the processes listed above. Processes rendering water potable but not necessarily closer to being pure H2O / hydroxide + hydronium ions include use of dilute sodium hypochlorite, mixed-oxidants (electro-catalyzed H2O + NaCl), and iodine.
Uses
Purified water is suitable for many applications, including autoclaves, hand-pieces, laboratory testing, laser cutting, and automotive use. drinking water is typically in the range of 5-50 mS/m, while highly purified water can be as low as 5.5 μS/m, a ratio of about 1,000,000:1,000:1.
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Distilled water is often defined as bottled water that has been produced by a process of distillation and has an electrical conductivity of not more than 10 µS/cm and total dissolved solids of less than 10 mg/litre. Distillation involves boiling the water and then condensing the vapour into a clean container, leaving solid contaminants behind. Distillation produces very pure water but also leaves behind a white or yellowish mineral scale on the distillation apparatus, which requires that the apparatus be frequently cleaned. Distillation does not guarantee the absence of bacteria in drinking water; unless the reservoir and/or bottle are sterilized before being filled, and once the bottle has been opened, there is a risk of presence of bacteria.
For many applications, cheaper alternatives such as deionized water are used in place of distilled water.
Double-distilled water is prepared by double distillation of water. Historically, it was the de facto standard for highly purified laboratory water for biochemistry and trace analysis until combination methods of purification became widespread.
Deionization
Deionized water, also known as demineralized water, is water that has had its mineral ions removed, such as cations from sodium, calcium, iron, copper and anions such as chloride and bromide. Deionization is a physical process which uses specially-manufactured ion exchange resins which bind to and filter out the mineral salts from water. Because the majority of water impurities are dissolved salts, deionization produces a high purity water that is generally similar to distilled water, and this process is quick and without scale buildup. However, deionization does not significantly remove uncharged organic molecules, viruses or bacteria, except by incidental trapping in the resin.
Deionization does not remove the hydroxide or hydronium ions from water. These are the products of the self-ionization of water to equilibrium and therefore are impossible to remove.
Other processesOther processes are also used to purify water, including reverse osmosis, carbon filtration, microporous filtration, ultrafiltration, ultraviolet oxidation, or electrodialysis. These are used in place of, or in addition to the processes listed above. Processes rendering water potable but not necessarily closer to being pure H2O / hydroxide + hydronium ions include use of dilute sodium hypochlorite, mixed-oxidants (electro-catalyzed H2O + NaCl), and iodine.
Uses
Purified water is suitable for many applications, including autoclaves, hand-pieces, laboratory testing, laser cutting, and automotive use. drinking water is typically in the range of 5-50 mS/m, while highly purified water can be as low as 5.5 μS/m, a ratio of about 1,000,000:1,000:1.
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Water for Health: Drinking Water
Drinking water or potable water is water of sufficiently high quality that can be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually consumed or used in food preparation.
Over large parts of the world, humans have inadequate access to potable water and use sources contaminated with disease vectors, pathogens or unacceptable levels of toxins or suspended solids. Such water is not potable, and 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 waterborne diseases is a major public health goal in developing countries.
Typical water supply networks deliver potable water from the tap, whether it is to be used for drinking, washing or landscape irrigation. One counterexample is urban China, where drinking water can optionally be delivered by a separate tap, often in the form of distilled water or otherwise the regular tap water needs to be boiled.
Water has always been an important and life-sustaining drink to humans and is essential to the survival of all organisms.
In emergency situations when conventional treatment systems have been compromised, water borne pathogens may be killed or inactivated by boiling but these suffer from the same problems as boiling methods.
Parameters for drinking water quality typically fall under two categories: chemical/physical and microbiological. Chemical/physical parameters include heavy metals, trace organic compounds, total suspended solids (TSS), and turbidity. Microbiological parameters include Coliform bacteria, E. coli, and specific pathogenic species of bacteria (such as cholera-causing Vibrio cholerae), viruses, and protozoan parasites.
Chemical parameters tend to pose more of a chronic health risk through buildup of heavy metals although some components like nitrates/nitrites and arsenic can have a more immediate impact. Physical parameters affect the aesthetics and taste of the drinking water and may complicate the removal of microbial pathogens.
Originally, fecal contamination was determined with the presence of coliform bacteria, a convenient marker for a class of harmful fecal pathogens. The presence of fecal coliforms (like E. Coli) serves as an indication of contamination by sewage. Additional contaminants include protozoan oocysts such as Cryptosporidium sp., Giardia lamblia, Legionella, and viruses (enteric). Microbial pathogenic parameters are typically of greatest concern because of their immediate health risk.
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Over large parts of the world, humans have inadequate access to potable water and use sources contaminated with disease vectors, pathogens or unacceptable levels of toxins or suspended solids. Such water is not potable, and 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 waterborne diseases is a major public health goal in developing countries.
Typical water supply networks deliver potable water from the tap, whether it is to be used for drinking, washing or landscape irrigation. One counterexample is urban China, where drinking water can optionally be delivered by a separate tap, often in the form of distilled water or otherwise the regular tap water needs to be boiled.
Water has always been an important and life-sustaining drink to humans and is essential to the survival of all organisms.
In emergency situations when conventional treatment systems have been compromised, water borne pathogens may be killed or inactivated by boiling but these suffer from the same problems as boiling methods.
Parameters for drinking water quality typically fall under two categories: chemical/physical and microbiological. Chemical/physical parameters include heavy metals, trace organic compounds, total suspended solids (TSS), and turbidity. Microbiological parameters include Coliform bacteria, E. coli, and specific pathogenic species of bacteria (such as cholera-causing Vibrio cholerae), viruses, and protozoan parasites.
Chemical parameters tend to pose more of a chronic health risk through buildup of heavy metals although some components like nitrates/nitrites and arsenic can have a more immediate impact. Physical parameters affect the aesthetics and taste of the drinking water and may complicate the removal of microbial pathogens.
Originally, fecal contamination was determined with the presence of coliform bacteria, a convenient marker for a class of harmful fecal pathogens. The presence of fecal coliforms (like E. Coli) serves as an indication of contamination by sewage. Additional contaminants include protozoan oocysts such as Cryptosporidium sp., Giardia lamblia, Legionella, and viruses (enteric). Microbial pathogenic parameters are typically of greatest concern because of their immediate health risk.
Learn Mandarin, Kanji, and Hangul here
Free Chinese/Mandarin Resources
What is Hiragana, Katakana, or Kanji?
Guide to Korea's Hangul System
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