Electrodeionization is a relatively novel technology for the production of ultra-pure water, without the use of chemicals. This is in principle accomplished by means of the combined use of spiral-wound membranes and ion-exchange resins. A continuous electric current source is connected to an anode and a cathode, which keep the resin activated while the electric field between anode and cathode facilitates the water electrolysis and the separation of the dissolved ions. Thanks to this process it is possible to produce high purity water (>17,5 MOhms . cm) from water which has been already demineralized by reverse osmosis deionization. The recovery ratio can exceed 95%. Watera’s EDI range is designed and manufactured according to the most stringent quality, safety and emission standards. Materials used, particularly those in contact with water, are of proven resistance to corrosion.