Refrigerators with built-in water dispensers provide instant access to chilled water and ice. This convenience often leads to confusion about the quality of the water being dispensed. Consumers frequently wonder if the water is simply filtered tap water or something more specialized, like distilled water. Understanding the difference requires looking at the specific processes each undergoes.
Defining Distilled Water
Distilled water is purified water created through a process that mimics the natural water cycle. This method involves boiling the source water until it turns into steam, leaving impurities behind. The steam is then captured, cooled, and condensed back into a liquid state.
This process is effective because most contaminants, including minerals, salts, and heavy metals, have higher boiling points than water. When the water evaporates, these dissolved substances are left behind, ensuring the resulting liquid is almost entirely pure water. This purification method is used for industrial, medical, and laboratory applications where dissolved solids could interfere with processes or equipment.
The Function of Refrigerator Water Filters
The water dispensed from a refrigerator relies on a different, less intensive method, primarily using filtration systems. Most refrigerator systems employ activated carbon, often derived from materials like coconut shells, to treat the incoming tap water. The process begins with mechanical filtration, where a pre-filter traps larger particles such as rust, dirt, and sediment.
The water then passes through the activated carbon block, where a chemical process called adsorption takes place. During adsorption, impurities like chlorine, which affects taste and odor, and certain volatile organic compounds (VOCs) are chemically bound to the carbon’s surface area. While these filters improve the water’s aesthetics and reduce some contaminants, they are not designed to remove all dissolved solids. Some advanced systems may incorporate an ion exchange resin to reduce heavy metals or scale, but the core function remains filtration, not distillation.
Comparing Mineral Content and Purity
The fundamental difference between the two types of water lies in their final composition, particularly their Total Dissolved Solids (TDS) content. TDS is a measurement of all inorganic and organic substances dissolved in water, expressed in parts per million (ppm). Distilled water, having gone through the boiling and condensation cycle, contains almost no dissolved solids, typically registering a TDS of 1 ppm or less.
In contrast, refrigerator-filtered water retains a significant amount of its original mineral content. Filtration systems do not strip the water of beneficial minerals like calcium and magnesium, which contribute to the water’s flavor. Consequently, refrigerator water is classified as filtered or purified water, not distilled, because it does not meet the near-zero TDS standard achieved by distillation.