Water distillation is a straightforward purification method that mimics the natural hydrologic cycle of evaporation and condensation to produce highly pure water. The process involves boiling water into steam and then cooling that steam back into a liquid state, leaving behind contaminants. This article provides practical guidance for home users, detailing the necessary equipment and a step-by-step method for safely distilling water in a standard kitchen environment.
Understanding Water Distillation and Purity
Distillation works because water has a significantly lower boiling point than most impurities found in tap water. As the water is heated to 212°F (100°C), the pure water molecules convert into vapor, leaving virtually all non-volatile substances behind in the boiling vessel. These contaminants include dissolved solids like calcium and magnesium, heavy metals such as lead, and inorganic salts. The high temperature also effectively kills microorganisms, including most bacteria and viruses. Distillation removes minerals that standard carbon filters often leave intact, making the resulting water exceptionally pure, often exceeding 99.9% purity from dissolved solids. Certain volatile organic compounds (VOCs) may vaporize and re-condense with the steam, but this is less of a concern for typical home tap water.
Essential Equipment for Home Distillation
The home distillation method requires only common kitchen tools, emphasizing the use of food-grade materials to prevent contamination. You will need a large, deep stainless steel pot to serve as the boiler for the source water. A smaller, heat-resistant collection container, such as a glass or ceramic bowl, must fit inside the pot, suspended above the source water.
A lid that fits securely over the large pot is needed, preferably one with a central handle or knob, as it will be inverted to create a condensing surface. Finally, a heat source, such as a stovetop burner, and a supply of ice are necessary. Avoid using aluminum or plastic containers in contact with the hot steam or water, as the high purity of distilled water can leach trace elements from non-food-grade materials.
Step-by-Step Guide to Distilling Water
To begin the process, fill the large stainless steel pot about one-third full with the source water you wish to purify. Carefully place the smaller, heat-safe collection bowl inside the pot so that it rests on a rack just above the water, ensuring no source water can splash into it. The collection bowl must be centered directly beneath where the distilled water will drip.
Next, place the lid upside-down on the large pot so that the condensation funnels to the center handle and drips into the collection bowl below. Turn the stovetop heat to a low-to-medium setting to bring the water to a gentle simmer, avoiding a rolling boil that could cause splashing and re-contaminate the collection bowl. Immediately place a generous amount of ice on top of the inverted lid, which dramatically cools the surface and accelerates condensation.
As the water simmers, steam rises, strikes the ice-cooled lid, and quickly converts back into liquid water droplets. These droplets follow the inverted lid’s curve, collect at the center point, and fall cleanly into the waiting collection bowl. Continually monitor the ice supply on the lid, replenishing it as it melts to maintain the necessary temperature differential. Once the desired amount of distilled water is collected, turn off the heat and use oven mitts to remove the hot lid and collection bowl, avoiding contact with the hot steam and water.
Appropriate Uses and Storage of Distilled Water
The high purity of the final product makes distilled water ideal for applications where mineral buildup or impurities could cause damage or interference. Common household uses include filling Continuous Positive Airway Pressure (CPAP) machines, steam irons, and humidifiers to prevent scale accumulation. It is also recommended for automotive batteries and certain sensitive laboratory or cosmetic preparations.
While distilled water is safe for short-term consumption, it lacks naturally occurring minerals like calcium and magnesium, which give tap water its taste and contribute to dietary intake. For storage, the distilled water should be transferred into clean, airtight containers made of glass or food-grade high-density polyethylene (HDPE) plastic. Storing the water in a cool, dark place is advisable, as an airtight seal prevents the re-absorption of atmospheric gases and airborne contaminants that could compromise its purity.