Distilled water is defined by its exceptional purity, distinguishing it significantly from common tap or spring water. This highly purified substance is essentially pure H₂O, stripped of nearly all dissolved solids, minerals, and contaminants. It is created through a natural process adapted for controlled environments, resulting in a blank slate uniquely suited for specific applications where the presence of other substances could be detrimental.
How the Distillation Process Works
The creation of steam distilled water replicates the natural hydrological cycle of evaporation and condensation within a controlled system. The process begins by heating source water to its boiling point, 212°F (100°C), transforming it into steam. This leaves behind substances that have a higher boiling point than water.
The pure water vapor is then guided into a cooling chamber, or condenser. Inside the condenser, the vapor loses heat and reverts to its liquid state, becoming distilled water. Impurities, including heavy metals, salts, and microorganisms, remain concentrated as a residue in the boiling vessel. This physical separation method ensures the resulting water is exceptionally clean because the impurities do not vaporize.
Defining the Purity Level
Distillation produces some of the purest water available by effectively removing a wide range of contaminants. The defining metric for this purity is the near-total absence of Total Dissolved Solids (TDS). Distilled water typically registers a TDS level of 0 to 5 parts per million (ppm), contrasting sharply with typical tap water, which often measures in the hundreds of ppm.
This process removes harmful substances like heavy metals and bacteria, but also beneficial elements such as calcium and magnesium. Consequently, the finished product contains almost no dissolved inorganic or organic compounds. Due to this extreme purity, the water is sometimes referred to as demineralized or deionized water.
Essential Uses Beyond Drinking
The ultra-high purity of distilled water makes it indispensable for applications where trace amounts of minerals or solids could cause interference or damage. It is required across several fields:
- Medical settings, where it is used for sterilizing surgical instruments in autoclaves and cleaning equipment like kidney dialysis machines.
- Laboratory analysis, where its neutrality ensures the accuracy of chemical solutions and experiments.
- Household appliances like steam irons and humidifiers, where it prevents the formation of mineral deposits that clog components.
- Automotive applications, such as lead-acid batteries and cooling systems, to prevent corrosion and mineral buildup.
Considerations for Human Consumption
Distilled water is considered safe to drink and contains no harmful contaminants or pathogens. However, the purification process eliminates all naturally occurring electrolytes and minerals. Due to the absence of these dissolved solids, some people find the taste of distilled water to be flat or bland.
Long-term, exclusive consumption of water lacking minerals like calcium and magnesium can be a concern if a person’s diet is already deficient. The World Health Organization notes that drinking water with low mineral content may potentially lead to increased urine output and a risk of electrolyte imbalance. For most healthy individuals who maintain a balanced diet, drinking distilled water poses no significant health risk, as necessary minerals are primarily obtained through food.