Water stills work by using a simple yet effective process called distillation to purify water. This process uses a basic heat source to boil and vaporize the water, which ensures that the water becomes separated from the contaminants that are present in it. This method has been used for centuries for various applications.
The Basic Principle: Separation Through Phase Change
At its core, a water still leverages the difference in boiling points between water and most contaminants. Water boils and turns into steam at a specific temperature (212°F or 100°C at sea level), while many dissolved impurities, minerals, salts, and other contaminants have much higher boiling points or don't vaporize easily at all.
By heating the water until it boils and turns into vapor (steam), the pure water separates from the substances left behind in the liquid state. The steam is essentially pure H₂O.
How the Process Unfolds: Key Steps
The process of water distillation typically involves three main steps:
- Heating and Vaporization: Raw water is placed in a boiling chamber. A heat source (like an electric element or a burner) is applied to bring the water to a boil. As the water boils, it transforms into steam.
- Condensation: The steam rises into a separate chamber or coil, often cooled by air or water. As the steam cools, it changes back into liquid water.
- Collection: The purified liquid water (distillate) is then collected in a separate container, leaving the contaminants behind in the original boiling chamber.
- Key Outcome: This cycle effectively separates the water molecules from most impurities, resulting in highly purified water.
Why Distillation is Effective
The power of distillation lies in this phase change. When water becomes steam, it leaves behind anything dissolved in it that doesn't vaporize at the same temperature. This includes:
- Minerals and salts
- Heavy metals
- Bacteria and viruses
- Many organic compounds and chemicals
While distillation removes a wide range of impurities, it's worth noting that substances with boiling points lower than water (like certain volatile organic compounds) might also vaporize and carry over into the collected water. However, for removing most common dissolved solids and biological contaminants, it is very effective.
Applications of Water Distillation
As mentioned, water distillation has been around for a long time and is used in many areas because of its ability to produce highly pure water.
- Laboratories: For experiments requiring high purity water.
- Medical Use: For sterilizers, dental practices, and some medical devices.
- Automotive: For car batteries and cooling systems.
- Household Use: For humidifiers, irons, and sometimes for drinking water (though it removes beneficial minerals).
- Industrial Processes: Where mineral-free water is essential.
The fundamental mechanism – heating water to separate it from contaminants via vaporization – is the core principle behind how water stills provide pure water.
