Pure Water

Purified water is water that has been mechanically filtered or processed to remove impurities and make it suitable for use. Distilled water has been the most common form of purified water, but, in recent years, 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 can be produced on site for immediate use or purchased in containers. Purified water in colloquial English can also refer to water which has been treated ("rendered potable") to neutralize, but not necessarily remove contaminants considered harmful to humans or animals.

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)

Purified water is suitable for many applications, including autoclaves, hand-pieces, laboratory testing, laser cutting, and automotive use. Purification removes contaminants that may interfere with processes, or leave residues on evaporation. Although water is generally considered to be a good electrical conductor—for example domestic electrical systems are considered particularly hazardous to people if they may be in contact with wet surfaces—pure water is a poor conductor. The conductivity of sea-water is typically 5 S/m, drinking water is typically in the range of 5-50 mS/m, while highly purified water can be as low as 5.5 μS/m (0.055 µS/cm), a ratio of about 1,000,000:1,000:1.

Purified water is used in the pharmaceutical industry. Water of this grade is widely used as a raw material, ingredient, and solvent in the processing, formulation, and manufacture of pharmaceutical products, active pharmaceutical ingredients (APIs) and intermediates, compendial articles, and analytical reagents. The microbiological content of the water is of importance and the water must be regularly monitored and tested to show that it remains within microbiological control.

Purified water is also used in the commercial beverage industry as the primary ingredient of any given trademarked bottling formula, in order to maintain critical consistency of taste, clarity, and color. This guarantees the consumer complete reliability of safety and drinking-satisfaction of their favorite refreshment, no matter where in the world it has been bottled. In the process prior to filling and sealing, individual bottles are always rinsed with deionised water to remove any particles that could cause a change in taste.

Deionised and Distilled water are used in lead-acid batteries to prevent erosion of the cells, although Deionised water is the better choice as more impurities are removed from the water in the creation process.