Untreated water is converted into water vapor, which is then condensed back into liquid form. Most of the contaminants are left behind in the boiling chamber.

Several types of steam distillation systems are available. The system selected depends on the quantity of water required. Single-stage distillers may produce from 1-gallon per day to 100 gallons per day. Commercial distillation units may produce 5,000 or more gallons per day.

Converting water into steam requires a significant amount of heat, which consumes energy.