An apparatus to remove ions, the apparatus having a housing including an inlet to let water in an interior of the housing, an outlet to let water out of the interior of the housing, a first electrode having a current collector, a second electrode, and a spacer to separate the first and second electrodes and to allow water to flow between the first and second electrodes. The apparatus also has a connector to connect the first electrode, or the second electrode, or both first and second electrodes, with an electrical source. The connector may have two connector parts to clamp the current collector in between the connector parts, the connector constructed and arranged to avoid water-metal contact.