Distilled water
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Distilled water is water that has virtually all of its impurities removed through distillation (boiling the water and re-condensing the steam into a clean container, leaving contaminants behind).
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[edit] Applications
In chemical and biological laboratories, as well as industry, cheaper alternatives such as deionized water are preferred over distilled water.[citation needed] 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 up lead acid batteries used in cars and trucks. The presence of other ions commonly found in tap water will cause a drastic reduction in its 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.
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.[citation needed]
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 used as a liquid that transfers heat in water cooling kits for computers. Due to the minute amount of pollutants in distilled water, it allows the transfer of super hot water without boiling and also the transfer of super cool water without freezing.
[edit] Drinking distilled water
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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. 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.
Water filtration devices are common in many households. Most of these devices do not distill water, though there continues to be an increase in consumer-oriented water distillers and reverse osmosis machines being sold and used. Municipal water supplies often add or have trace impurities at levels which are regulated to be safe for consumption. Much of these additional impurities, such as volatile organic compounds, fluoride, and an estimated 75,000+ other chemical compounds[citation needed] are not removed through conventional filtration; however, distillation does eliminate nearly all of these pollutants.
Distilled water is also used as drinking water in arid seaside areas which do not have sufficient freshwater, by distilling seawater. It is quite common on ships, especially nuclear powered ships, which require a large supply of distilled water as coolant. The drinking water is produced in desalination plants, although it is very expensive due to the large amount of fuel needed to boil water. Alternative technologies like reverse osmosis are becoming increasingly important in this regard due to their greatly reduced costs.
[edit] Pros and cons
The drinking of distilled water has been both advocated and discouraged for health reasons.
The lack of naturally-occurring minerals in distilled water has raised some concerns. According to a 2005 World Health Organization study[1], consumption of demineralized water is associated with adverse health effects including reduced skeletal ossification, decreased levels of necessary bodily minerals, and increased morbidity and mortality from cardiovascular disease; an increased intake of toxic metals is also possible. The study also indicates that cooking in demineralized water "was found to cause substantial losses of all essential elements from food."
It has been suggested that -- because distilled water lacks fluoride ions that are added by many governments (e.g. municipalities in the United States) at water treatment plants using fluoridation for its supposed effect on the inhibition of cavity formation -- the drinking of distilled water may conceivably increase the risk of tooth decay due to a lack of this element.[2]
A purported effect of drinking water in its pure form is a 'more powerful solvent' that helps cleanse toxins from the body[citation needed].
The cost of distilling water (about 0.04 to 0.10 Euro or USD per litre in 2005) prohibits its use by most households worldwide.[citation needed]
[edit] Myths
A popular myth about distilled water is that it has the dangerous property of being more easily heated above its normal boiling point without actually boiling in a process known as superheating. When the superheated water is disturbed or has impurities added to it, a nucleation center for bubbles form. These bubbles formed are new nucleation centers, and a sudden, explosive boil occurs, possibly causing serious injury to anyone near it.
In fact, superheating of plain tap water, for instance in the microwave, is just as great a danger as when heating distilled water. In the popular Discovery Channel show Mythbusters, an experiment was conducted where distilled water was placed in a microwave oven for several minutes long enough to boil, but no convection (boiling bubbles) took place.[citation needed] When a contaminant (a sugar cube) was added to the superheated water, it had an explosive effect. However, this effect also occurs with normal tap water, as microscopic impurities (especially those which carry air bubbles) are needed for boiling to start.The dissolved impurities in tap water are not enough to inhibit the superheating.
[edit] References
[edit] See also
- Deionized water
- Atmospheric water generator (Make distilled water from air)
- Heavy water
