What is distilled water

Overview

Distilled water is water that has undergone a purification process called distillation, which separates water molecules from dissolved minerals, chemicals, and other contaminants through evaporation and condensation. The result is the purest form of water commonly available, containing virtually no dissolved solids, minerals, or trace elements. Unlike tap water, which typically contains 50-500 parts per million (ppm) of dissolved minerals depending on location, distilled water contains fewer than 1 ppm of dissolved solids. The term "distilled" comes from the Latin word "distillare," meaning to drip or trickle, referring to the slow condensation process that produces this ultra-pure water.

The Distillation Process

Water distillation involves several distinct steps that ensure the removal of impurities. First, tap water or source water is heated in a distillation unit until it reaches 100°C (212°F), converting it into steam. As the water transforms into vapor, dissolved minerals, salts, bacteria, viruses, and most chemical contaminants remain behind in the boiling chamber because they have higher boiling points than water. The pure steam rises and enters a condensation chamber where cooling coils or circulating cool water reduces the temperature to approximately 50-60°C, causing the steam to return to liquid form. This condensed water is then collected in a separate, clean container. A single distillation cycle removes approximately 99.5% of contaminants, though double or triple distillation can achieve even higher purity levels of 99.9% or greater. The entire process typically takes 3-5 hours per gallon of distilled water produced. Industrial distillation plants can produce 50-500 gallons per day depending on equipment size and capacity.

Common Misconceptions

Misconception 1: Distilled water is the healthiest water to drink. While distilled water is extremely pure, it lacks essential minerals like calcium, magnesium, potassium, and sodium that the human body requires. Studies show that regular consumption of completely demineralized water can lead to mineral deficiencies and may increase the risk of cardiovascular issues according to some research. The World Health Organization has noted that drinking water typically contributes 10-15% of daily calcium and magnesium intake, and distilled water provides zero contribution. Most health experts recommend distilled water be used for specific purposes rather than as everyday drinking water.

Misconception 2: All distilled water is identical. The purity level of distilled water can vary significantly depending on the quality of the source water, the distillation equipment used, and the number of distillation cycles performed. Water distilled once may contain 10-50 ppm of residual minerals, while laboratory-grade distilled water undergoes multiple cycles to achieve 0.5-1 ppm. Additionally, distilled water readily absorbs carbon dioxide from the air, forming carbonic acid and lowering its pH from neutral (7.0) to acidic (5.5-6.0) within hours of exposure to air. This is normal and does not indicate contamination.

Misconception 3: Distillation removes all contaminants. While distillation is highly effective, it does not remove all volatile organic compounds (VOCs) or some gases that boil at temperatures below or near 100°C. However, distillation does remove approximately 99% of heavy metals including lead, mercury, and cadmium, making it far superior to simple filtration for these contaminants. Boiling point-specific contaminants may require additional filtration methods for complete removal.

Practical Uses and Considerations

Distilled water serves critical functions in numerous applications where mineral content would cause damage or contamination. In automotive applications, car batteries require distilled water because tap water's minerals would create sulfate buildup on battery plates, reducing efficiency by 20-30% and shortening battery lifespan from 5-7 years to 2-3 years. Steam irons use distilled water to prevent mineral deposits that clog steam vents and reduce ironing effectiveness. Laboratory and medical equipment requires distilled water to ensure accurate test results and prevent equipment damage; hospitals use approximately 100-200 gallons of distilled water daily for medical equipment and procedures. Aquariums use distilled water to prevent mineral imbalances that harm sensitive fish species and plants. CPAP machines for sleep apnea treatment specifically require distilled water in humidifiers to prevent mineral buildup.

For household consumption, most health professionals recommend using distilled water only occasionally or as part of a mixed water intake that includes mineral-containing water. If someone chooses to drink distilled water regularly, they should ensure adequate mineral intake through diet and supplements. A balanced approach involves using tap water or filtered water that retains beneficial minerals for daily consumption while using distilled water for specific applications where mineral content is problematic. Store-bought distilled water typically costs $1-3 per gallon, while home distillation units cost $50-150 and produce distilled water at approximately $0.50-1.00 per gallon over time.