The dissolved substances, such as sulfate, are left behind in the boiling pot. With proper operation, distillation units can remove nearly 100 percent of sulfate. Distillation units require about four hours to produce 1 gallon of water, so this type of treatment uses a considerable amount of energy in its operation. Ion Exchange is the most common method of removing large quantities of sulfate from water for commercial, livestock, and public supplies, but is not commonly used for individual household water treatment. It is a process where one element or chemical is switched for another.
Many people are familiar with water softening, one common type of ion exchange system.
The hardness minerals stick to the resin, and the sodium is dissolved in the water. Ion exchange systems for removal of sulfate work in a similar manner, but use a different type of resin. Sulfate ions in the water exchange places with other ions, usually chloride, which is on the resin. Water softeners for removal of hardness do not remove sulfate, and sulfate removal systems do not remove hardness, although some commercial units contain both resins and can remove both hardness and sulfate. If both a water softener and a sulfate removal system are used, the water softener is usually placed before the sulfate removal system.