An apparatus provided with a flow through capacitor for removal of ions in water provided with a plurality of capacitive electrode stacks (A, B), each capacitive electrode stack (A, B) comprising: a plurality of first electrodes (e.g. anodes during ion removal from water) provided with a plurality of first current collectors (13, 13A, 13B)), wherein first current collectors 13A of the plurality of first current collectors of the individual capacitive electrode stacks are directly electrically connected with each other in parallel between clamp portions; a plurality of second electrodes (e. g. cathodes during ion removal from water) provided with a plurality of second current collectors (15, 15A, 15B); and, a spacer between the first and second electrodes (13, 13A, 13B, 15, 15A, 15B) for allowing water to flow in parallel between the electrodes, wherein the plurality of second current collectors (15, 15A, 15B) of a first of the plurality of capacitive electrode stacks are directly electrically connected in series to the plurality of first current collectors (13, 13A, 13B); of a second of the plurality of capacitive electrode stacks, wherein a clamp is provided to press the plurality of first and second current collectors (13B, 15A) against each other to electrically connect the plurality of first and second current collectors (13B, 15A) in series, wherein the apparatus is provided with a housing (1,3), the apparatus comprising: a water inlet for water entering an interior of the housing (1,3); a water outlet for letting water out of the interior of the housing (1,3) and the plurality of second current collectors (15, 15A, 15B) of the first of the plurality of capacitive electrode stacks, which are electrically connected to the plurality of first current collectors (13, 13A, 13B) of the second of the plurality of capacitive electrode stacks within the same housing (1,3). a plurality of first electrodes (e.g. anodes during ion removal from water) provided with a plurality of first current collectors (13, 13A, 13B)), wherein first current collectors 13A of the plurality of first current collectors of the individual capacitive electrode stacks are directly electrically connected with each other in parallel between clamp portions; a plurality of second electrodes (e. g. cathodes during ion removal from water) provided with a plurality of second current collectors (15, 15A, 15B); and, a spacer between the first and second electrodes (13, 13A, 13B, 15, 15A, 15B) for allowing water to flow in parallel between the electrodes, wherein the plurality of second current collectors (15, 15A, 15B) of a first of the plurality of capacitive electrode stacks are directly electrically connected in series to the plurality of first current collectors (13, 13A, 13B); of a second of the plurality of capacitive electrode stacks, wherein a clamp is provided to press the plurality of first and second current collectors (13B, 15A) against each other to electrically connect the plurality of first and second current collectors (13B, 15A) in series, wherein the apparatus is provided with a housing (1,3), the apparatus comprising: a water inlet for water entering an interior of the housing (1,3); a water outlet for letting water out of the interior of the housing (1,3) and the plurality of second current collectors (15, 15A, 15B) of the first of the plurality of capacitive electrode stacks, which are electrically connected to the plurality of first current collectors (13, 13A, 13B) of the second of the plurality of capacitive electrode stacks within the same housing (1,3).