Water is fundamental to life, yet its various treated forms often lead to confusion. Many people encounter terms like “purified water” and “distilled water” and assume they are interchangeable. While both undergo processes to remove impurities, their production methods and resulting characteristics differ, making them distinct forms of treated water. This exploration will clarify these differences.
What is Purified Water?
Purified water originates from sources like tap water or groundwater and undergoes treatment to remove impurities and contaminants. Multiple methods are employed to achieve this cleanliness.
Reverse osmosis (RO) forces water through a semi-permeable membrane, filtering out dissolved solids, chemicals, and microorganisms. Activated carbon filtration uses carbon’s porous nature to adsorb chlorine and substances causing unpleasant tastes. Deionization removes inorganic ions using ion-exchange resins, and ultraviolet (UV) sterilization disinfects water by killing bacteria and viruses.
The goal of purification is a high level of cleanliness, often defined by a total dissolved solids (TDS) level of less than 10 parts per million (ppm). Depending on the specific system, some beneficial minerals may or may not be retained.
What is Distilled Water?
Distilled water is a specific type of purified water produced through distillation. This method involves heating water to its boiling point, transforming it into steam. As the water vapor rises, it leaves behind dissolved solids, minerals, and many other impurities that do not vaporize.
The steam is then collected and cooled in a separate container, condensing back into liquid water. This process is highly effective at removing a wide range of contaminants, including bacteria, viruses, protozoa, and various chemicals. The resulting water is exceptionally pure, with a very low mineral content, often 1-5 ppm TDS or even less.
Comparing Purified and Distilled Water
The primary distinction between purified and distilled water lies in their production methods and resulting mineral content. Purified water can be produced through various treatment processes, including reverse osmosis, deionization, and carbon filtration, either individually or in combination. Distilled water, by contrast, is exclusively produced via the distillation process. This difference in methodology leads to variations in their final composition.
Distilled water consistently lacks virtually all dissolved minerals, as the boiling and condensation process separates them. Purified water, depending on the specific purification techniques employed, may retain some minerals or have them re-added after treatment. Consequently, distilled water typically exhibits a lower TDS level, often near 0 ppm, compared to general purified water which must be below 10 ppm. This absence of minerals can give distilled water a noticeably flat or bland taste, whereas purified water may have a more palatable flavor due to the potential presence of trace minerals.
Choosing the Right Water for Your Needs
Selecting between purified and distilled water depends largely on the intended application. For daily drinking, purified water is generally a suitable choice, especially if it retains some beneficial minerals or has them added back. While distilled water is safe to drink, its lack of minerals can result in a flat taste, and some individuals may prefer to ensure their mineral intake through diet or other water sources.
In household appliances like clothes irons, humidifiers, or CPAP machines, distilled water is often recommended to prevent the buildup of mineral deposits, which can damage the equipment over time. Purified water with very low mineral content can also serve this purpose effectively.
For scientific laboratories, medical procedures, or industrial processes requiring high purity and the absence of any interfering substances, both distilled water and ultra-pure forms of purified water are employed. The specific requirements of the application will dictate the appropriate level of water purity needed.