Hygiea water is 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 Hygiea includes capacitive deionization, reverse osmosis, carbon filtering, microfiltration, ultrafiltration, ultravioletoxidation, or electrodeionization. Combinations of a number of these processes have come into use to produce 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.