The terms “still water” and “distilled water” are often mistakenly used interchangeably, but they refer to two fundamentally different classifications of water. Still water is defined by its physical state, whereas distilled water is defined by its intensive purification process.
What Defines Still Water
Still water is simply water that is not carbonated, meaning it contains no dissolved carbon dioxide gas. This classification is based entirely on the water’s physical property, not its purity or source. Still water can come from a variety of sources, including tap water, spring water, or purified water, as long as it lacks fizz.
The composition of still water is highly variable and depends on its origin. Water sourced from underground springs or aquifers naturally picks up varying levels of minerals, salts, and other Total Dissolved Solids (TDS). Even filtered still water contains some level of these dissolved components, which contribute to its taste and electrical conductivity.
The Purification Process of Distilled Water
Distilled water is created through a specific thermal process that mimics the natural hydrologic cycle of evaporation and condensation. The process begins by heating the source water in a boiling chamber until it vaporizes into steam. This intense heating is sufficient to kill most microorganisms, including bacteria and viruses.
As the water turns to steam, all non-volatile components, such as minerals, salts, and most Total Dissolved Solids, are left behind in the boiling chamber. The pure steam is then channeled into a separate condensing chamber, where it is cooled and converted back into liquid water. This condensed liquid is collected as distilled water, which is nearly 100% pure H₂O, typically having a Total Dissolved Solids count of less than one part per million (PPM).
Compositional Differences and Taste
The core difference between the two types lies in their chemical composition, specifically the presence or absence of Total Dissolved Solids (TDS). Still water, regardless of its source, retains its natural mineral profile, which often includes compounds like calcium, magnesium, and potassium. This mineral content is what gives still water its characteristic flavor profile.
Distilled water, having gone through the rigorous boiling and condensation process, is essentially devoid of these dissolved minerals and solids. The resulting lack of these compounds makes distilled water chemically unreactive and gives it a distinct sensory profile. Many people describe the taste of distilled water as “flat” or sometimes slightly metallic because the minerals responsible for the familiar taste of drinking water have been removed.
Intended Uses for Each Type
Still water is primarily intended for drinking and everyday consumption because its mineral content provides the familiar taste and contributes small amounts of dietary electrolytes. It is the preferred choice for hydration, cooking, and beverages where taste and a natural composition are desired.
Distilled water, due to its exceptional purity and lack of mineral deposits, is reserved for applications where mineral buildup is detrimental. It is the standard for laboratory experiments, medical equipment sterilization, and use in Continuous Positive Airway Pressure (CPAP) machines. Distilled water is also recommended for use in steam irons, car batteries, and humidifiers to prevent the formation of limescale and corrosion.