Purified water is water that has been filtered or processed to remove impurities and make it suitable for use. The impurities that may need to be removed include bacteria, algae, fungi, parasites, metals like copper and lead, and chemical pollutants. Purified water can be made from tap water or groundwater, and it is produced in a range of purities. There are several methods used to purify water commercially and in the home, including filtration, reverse osmosis, distillation, and deionization. Purified water is often used in the production of medications, in science and engineering laboratories and industries, and in the commercial beverage industry as the primary ingredient of any given trademarked bottling formula, in order to maintain product consistency.
It is important to note that purified water is not the same as filtered water. While both types of water are subject to some sort of filtration, purified water is cleansed and purified through additional purification processes, typically reverse osmosis, distillation, or deionization, to remove impurities and contaminants.
In colloquial English, purified water can also refer to water that has been treated to neutralize, but not necessarily remove, contaminants considered harmful to humans or animals.
To meet the legal definition of “purified water,” water impurities must be removed or reduced to extremely low levels. The impurity load of dissolved solids in purified water cannot exceed 10 parts-per-million, and water that meets this threshold is inherently of a higher purity than spring water, tap water, or filtered water.
