Distillation process as a water treatment has the advantage of removing more contaminants than any other treatment. It has no consumables, and has very simple equipment. In distillation the water is heated to a vapor. The vapor collection begins when the vapor reaches 100 deg C, this eliminates low boiling organics from the distilled water but not necessarily higher boiling organics. Also removed are particulates, some dissolved solids, microorganisms, and endotoxins. The steam is cooled and collected in a tank as distilled water. Distilled water can be type II or type III water depending on the conductivity of the feed water. To produce Type I water further deionization would be necessary to lower the conductivity.
Distillation requires more water for cooling than is produced as distilled water. Only about 5% of the water used in the distillation process becomes purified water. The distilled water cannot be used on demand, it must be stored. Storage tanks can be sterilized but if the water is exposed to air contamination is introduced. Regular cleaning of mineral build up and disinfecting of the distillation unit is required.