An electrode for deionization of water is made of a continuous activated carbon structure. The activated carbon is derived from a synthetic carbon precursor. The structure has openings, inlet and outlet ends such that water entering the inlet end passes through the openings and exits through the outlet end, a conductive coating on at least part of the outer surface of the structure, and a metal wire in contact with the structure. A deionization system is made up of the electrodes in series so that the outlet end of one electrode is next to the inlet end of the nearest downstream electrode. The metal wire of each electrode is connected to a power source to deliver the opposite charge as the charge delivered to its neighboring electrodes. Each of the electrodes is fixedly attached to and sealed within a housing with an air and moisture-tight seal. Openings in the housing between the electrodes, allow air to be removed before use. A method of removing ions from a stream of water involves removing air from the system by applying a vacuum to the housing openings and sealing the housing openings, passing a current through the device, and passing a stream of water containing ions through it to remove the ions.