Boiled water and distilled water are often confused, but they are fundamentally different products created through distinct processes. While both methods involve the application of heat to water, their respective goals and final compositions vary significantly. Boiling is a simple heat-based treatment for immediate safety, while distillation is a multi-step physical separation process designed for achieving high purity. Understanding the difference between these two forms of treated water comes down to knowing what impurities are removed and what is left behind.
The Purpose and Outcome of Boiling Water
Boiling water is an ancient and effective method focused primarily on microbiological safety. This process involves heating water until it reaches its boiling point of 212°F (100°C) and maintaining that temperature for a specified period, typically one to three minutes. The intense heat kills or deactivates biological threats, including bacteria, viruses, and protozoa, which are major causes of waterborne illnesses. Boiling is frequently recommended in emergency situations or when a water source is compromised by microbial contamination.
Boiling water does not remove non-biological contaminants. Dissolved solids, such as minerals like calcium and magnesium, remain in the water, as do heavy metals, pesticides, and industrial chemicals. Since some water evaporates during boiling, the concentration of these non-volatile impurities actually increases in the remaining liquid. Consequently, boiled water is biologically safe but retains the chemical and mineral characteristics of the original source water.
The Method and Result of Distilling Water
Distillation is a purification method that separates water from contaminants through a phase change. The process starts by heating the source water until it vaporizes into steam. This steam is channeled away from the original container, leaving behind virtually all non-volatile substances. These substances include dissolved minerals, salts, heavy metals, and most inorganic compounds.
The pure water vapor is then cooled in a separate chamber, causing it to revert back to its liquid state, known as distilled water. This physical separation ensures the resulting water is free from nearly all impurities, achieving a high level of purity. However, volatile organic compounds (VOCs) that boil at or below the temperature of water may vaporize along with the water and potentially re-contaminate the final product. Specialized equipment addresses this by venting these compounds or incorporating additional filtration steps.
Comparing the Final Products: When to Use Each
The primary difference between the final products lies in their total dissolved solids (TDS) content. Boiled water retains the natural mineral and salt content of the source water, meaning its TDS level is largely unchanged or slightly concentrated. Distilled water, by contrast, has had all minerals and dissolved solids physically separated, resulting in a TDS level near zero.
The lack of minerals gives distilled water a distinctively flat or bland taste, as the flavor profile of water is influenced by its dissolved components. Boiled water, retaining its mineral content, generally tastes the same as the source water. It may, however, be perceived as flat due to the loss of some dissolved gases like oxygen.
The applications for each type of water reflect their compositions. Boiled water is used for immediate consumption, especially for emergency drinking or cooking, where the primary concern is eliminating waterborne pathogens. Distilled water is reserved for specialized uses where mineral deposits are unacceptable.
Specialized Uses for Distilled Water
Distilled water is used in applications requiring extremely high purity to prevent interference or scale buildup, including:
- Filling car batteries.
- Operating steam irons and humidifiers.
- Specific medical and pharmaceutical processes.
- Laboratory procedures.