Reverse osmosis (RO) water and distilled water are often confused, as both methods purify water by removing impurities. While both processes yield water significantly cleaner than typical tap water, they employ distinct mechanisms and result in different levels of purity and characteristics. Understanding these distinctions is important for choosing the appropriate water type for various applications.
Understanding Reverse Osmosis (RO) Water
Reverse osmosis is a water purification method that uses pressure to force water molecules through a semi-permeable membrane. This membrane allows water to pass through while rejecting most dissolved solids and larger molecules. The process removes a wide range of contaminants, including dissolved salts, minerals like calcium and magnesium, heavy metals such as lead and arsenic, chlorine, and many organic chemicals.
RO systems also remove biological contaminants like bacteria, viruses, and protozoa. However, some dissolved gases, such as carbon dioxide, are not effectively removed by RO membranes. RO water may still retain trace amounts of certain substances.
Understanding Distilled Water
Distilled water is produced by heating water to its boiling point, converting it into steam. Impurities, including minerals, chemicals, bacteria, and viruses, have higher boiling points than water and are left behind in the boiling chamber.
The steam then rises into a separate chamber where it is cooled and condensed back into liquid water. This process removes nearly all impurities, resulting in water free of dissolved solids. However, some volatile organic compounds with lower boiling points than water may vaporize and re-contaminate the water if not addressed by post-filtration.
Key Differences and Practical Applications
The key difference between reverse osmosis and distilled water lies in their purification processes and resulting purity levels. Distilled water, created by boiling and condensation, generally achieves a higher level of purity by removing almost all dissolved solids and minerals, often reaching 99.9% purity. Reverse osmosis, using a membrane, typically removes 90-99% of contaminants.
Distilled water is completely demineralized, leaving it devoid of both beneficial and harmful minerals. RO water, conversely, removes most but not all minerals, with a small percentage potentially remaining depending on the system and source water. This difference in mineral content impacts taste; distilled water often has a flat or bland taste because of the complete absence of minerals. RO water, particularly if remineralized post-filtration, can have a more palatable taste.
Distilled water is used in applications where mineral buildup or contamination is avoided. Common uses include medical equipment sterilization, laboratory experiments, CPAP machines, car batteries, and steam irons. The absence of minerals prevents scale formation and interference with sensitive processes.
Reverse osmosis water has broader applications, including home drinking water systems, aquariums, and various industrial processes like food and beverage production. It provides clean, safe water for consumption and is also used in commercial settings such as coffee shops and car washes. The choice between RO and distilled water often depends on the specific purity requirements and intended use.