The terms “distilled water” and “pure water” are often used interchangeably, leading to confusion. While both relate to water with reduced contaminants, they are not always the same. Understanding their specific characteristics and processes helps clarify this distinction.
What Does “Pure Water” Mean?
Pure water, scientifically referred to as H₂O, represents water with virtually all impurities removed. This includes dissolved minerals, salts, gases, organic compounds, and biological contaminants. In natural environments, truly pure water is exceptionally rare because water is a universal solvent, readily dissolving and carrying various substances. Therefore, highly pure water typically requires specific treatment processes to remove these dissolved and suspended materials.
The Process of Distillation
Distillation is a method for purifying water, designed to separate water from its impurities using a phase change. The process begins by heating water to its boiling point, transforming it into steam. As it vaporizes, it leaves behind most non-volatile contaminants like minerals, salts, and heavy metals. This purified steam is then collected and cooled, condensing back into liquid distilled water. While highly effective at removing a broad range of impurities, distillation can sometimes allow contaminants with similar boiling points or tiny liquid droplets to carry over.
Key Distinctions and Overlaps
While distilled water is a form of pure water, the terms are not synonymous; distilled water represents a specific subset. The broader category of “pure water” encompasses any water treated to remove contaminants, regardless of the purification method used. Distillation achieves a high level of purity by boiling and condensation, effectively removing dissolved solids and biological agents. However, other purification methods also produce water with varying degrees of purity.
Reverse osmosis (RO) forces water through a semi-permeable membrane, filtering out dissolved salts, ions, and larger particles. Deionization (DI) uses ion-exchange resins to remove charged mineral ions, yielding water with very low conductivity. These processes, along with carbon filtration and ultraviolet oxidation, can produce water considered pure for various applications without distillation. Therefore, while all distilled water is pure, not all pure water is distilled.
Everyday Applications and Health Aspects
Distilled water finds many practical uses where the absence of minerals is beneficial. It is commonly used in household appliances like steam irons and humidifiers to prevent mineral buildup and extend the appliance’s lifespan. In automotive applications, distilled water is preferred for car batteries and cooling systems to avoid corrosion and scale formation. Laboratories and medical facilities rely on distilled water for preparing solutions, sterilizing equipment, and sensitive analytical procedures.
Regarding consumption, distilled water is generally safe to drink occasionally. However, it lacks naturally occurring minerals like calcium and magnesium found in tap water. Regular consumption of water devoid of these minerals is not typically recommended as a primary source of hydration, as it may not contribute to the body’s mineral intake. While useful in specific situations, most people obtain necessary minerals from a balanced diet and mineral-containing drinking water.