Electrodeionization, also referred to as Continuous Electrodeionization (CEDI) and Continuous Deionization (CDI), is a chemical-free technology that significantly reduces ions in water. CEDI uses cation and/or anion exchange resins that are continuously regenerated by an electrical current. EDI modules, also called “stacks,” consist of cell pairs with each pair containing an anode and cathode on separate sides. Each cell consists of a frame onto which are bonded a cation-permeable membrane on one side, and an anion-permeable membrane on the other.