Distilled water

Distilled water is water that has had many of its impurities removed through distillation. Distillation involves boiling the water and then condensing the steam into a clean container.

Drinking water has been distilled from sea water since at least about AD 200, when the process was clearly described by Alexander of Aphrodisias. Its history predates this, as a passage in Aristotle's Meteorologica (II.3, 358b16) refers to the distillation of water. Captain Israel Williams of the Friendship (1797) improvised a way to distill water, which he described in his journal.

In chemical and biological laboratories, as well as in industry, cheaper alternatives such as deionized water are preferred to distilled water. But if these alternatives are not pure enough, distilled water is used. If 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 drastically reduce an automobile battery's 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 faster 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.

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