Purified water

Purified water is water that has been mechanically filtered or processed to remove impurities and make it suitable for use. Distilled water was the most common form of purified water but water is more frequently purified by other processes including capacitive deionization, reverse osmosis, carbon filtering, microfiltration, ultrafiltration, ultraviolet oxidation, or electrodeionization. Combinations of a number of these processes have come into use to produce ultrapure water of such high purity that its trace contaminants are measured in parts per billion (ppb) or parts per trillion (ppt).

Purified water has many uses, largely in the production of medications, in science and engineering laboratories and industries, and is produced in a range of purities. It is also used in the commercial beverage industry as the primary ingredient of any given trademarked bottling formula, in order to maintain product consistency. It can be produced on-site for immediate use or purchased in containers. Purified water in colloquial English can also refer to water that has been treated ("rendered potable") to neutralize, but not necessarily remove contaminants considered harmful to humans or animals.

Parameters of water purity

Purified water is usually produced by the purification of drinking water or ground water. The impurities that may need to be removed are:

inorganic ions (typically monitored as electrical conductivity or resistivity or specific tests)

organic compounds (typically monitored as TOC or by specific tests)

bacteria (monitored by total viable counts or epifluorescence)

endotoxins and nucleases (monitored by LAL or specific enzyme tests)

particulates (typically controlled by filtration)

gases (typically managed by degassing when required)

Purification methods

Distillation

Distilled water is produced by a process of distillation. Distillation involves boiling the water and then condensing the vapor into a clean container, leaving solid contaminants behind.