During distillation the water is heated to form steam. The steam is cooled and condenses to form purified water. Unevaporated contaminants are left behind and periodically flushed to the septic or sewer system. Distillers are POU systems and may be countertop, wall mounted, or placed on carts. Systems can be manual, partially or fully automated.
Some models can separate volatile organic compounds before distillation.
An advantage of distillation for use on water supplies which have not been chlorinated is that disinfection occurs during boiling. Care must be taken to avoid recontamination of the condensed purified water in the storage container by bacteria. Problems associated with distillation include loss of beneficial minerals from water and water that may taste flat. Operating costs may be higher than other forms of home treatment. Production of heat from a distiller may be beneficial in the winter but a disadvantage in the summer.