The Distillation Process
Water distillation is a purification method that replicates the Earth’s natural water cycle in a controlled environment. This process separates water from its impurities by leveraging differences in boiling points. It aims to achieve high water purity, isolating pure water molecules from dissolved solids, contaminants, and microorganisms. This technique creates water suitable for applications demanding exceptional purity.
The Distillation Steps
Water purification through distillation begins by heating the source water in a boiling chamber. As heat is applied, the water’s temperature rises to its boiling point, typically 212 degrees Fahrenheit (100 degrees Celsius) at standard atmospheric pressure. At this temperature, water molecules gain enough energy to transition from liquid to gas, forming steam.
During vaporization, most impurities present in the original water remain in the boiling chamber. These contaminants, including dissolved minerals, heavy metals, and various organic compounds, possess significantly higher boiling points than water. Consequently, they do not vaporize with the water, remaining as residue.
The generated steam then travels from the boiling chamber into a cooling condenser. This condenser typically consists of a coiled tube or a series of tubes surrounded by a cooler medium, such as circulating tap water or air. As the hot steam contacts the cooler surfaces, it rapidly loses heat energy.
This energy loss causes the steam to revert from a gaseous state back into liquid water droplets, a process known as condensation. The condensed, purified water then flows down and is collected in a separate, clean container, completing the distillation cycle.
What Distillation Removes and Doesn’t Remove
Water distillation effectively removes a wide array of contaminants due to the fundamental principle of phase change. The process eliminates dissolved solids, including minerals like calcium, magnesium, and sodium, which have boiling points far exceeding water. Heavy metals such as lead, mercury, and arsenic are also separated as they remain in the boiling chamber.
Distillation also removes biological impurities, including bacteria, viruses, and protozoa, as these microorganisms cannot survive the high temperatures of the boiling process. Many non-volatile organic compounds or those with significantly higher boiling points than water are also left behind.
However, distillation has limitations, particularly concerning volatile organic compounds (VOCs). Substances like benzene, toluene, and some pesticides have boiling points similar to or even lower than water. This means they can vaporize along with the water during heating and subsequently condense with the purified water.
While distillation removes most dissolved solids and biological contaminants, it may not completely eliminate all VOCs. When VOC removal is a concern, additional purification methods, such as activated carbon filtration, are often employed in conjunction with distillation for comprehensive purification.
Common Applications of Distilled Water
The purity of distilled water makes it suitable for specific applications where minerals or other impurities could cause issues. In medical and laboratory settings, it is used for sterilizing surgical instruments, preparing precise chemical solutions, and in medical devices requiring water free from mineral buildup, such as autoclaves. Its purity prevents contamination and unwanted reactions.
Automotive systems benefit from distilled water, particularly in car batteries and cooling systems. Using distilled water prevents mineral deposit accumulation, which can corrode components and reduce efficiency over time.
Within households, distilled water is recommended for appliances like steam irons, humidifiers, and CPAP (Continuous Positive Airway Pressure) machines. The absence of minerals prevents scale buildup on heating elements and internal components, extending device lifespan and ensuring proper function. Regular tap water, with its mineral content, can quickly lead to blockages and damage.
Beyond these common uses, distilled water applies to various industrial processes, including electronics manufacturing, where trace impurities can compromise product integrity. While pure, distilled water lacks naturally occurring minerals found in tap water, a consideration for long-term human consumption without mineral supplementation.