A desalination system for the removal of ions and hardness ions from an aqueous stream, comprising: at least one desalination cell comprising: first and second electrodes (22, 23); an anion exchange layer and a cation ion exchange layer disposed on the respective first and second electrodes; a spacer disposed between the first and second electrodes (22, 23); and ion exchange resin disposed between the first and second electrodes (22, 23);wherein the ion exchange resin comprises a mixture of anion exchange resin beads and cation exchange resin beads, the proportion of volumes of the anion exchange resin beads and the cation exchange resin beads being 1:1; wherein the desalination cell is configured to receive a first feed stream having salts or other impurities from a first liquid source for desalination so as to remove charged species or target ions therein to produce an effluent stream; wherein the desalination cell is configured to receive a second feed stream from a second liquid source after desalination of the first feed stream so as to carry the charged species or target ions removed from the first feed stream out of the desalination apparatus to produce a concentrate stream which has a higher concentration of charged species than the second feed stream; and the desalination system comprising a first valve and a second valve, the first valve and the second valve being configured so that the flow paths of the second feed stream and the concentrate stream are closed during removal of charged species or target ions, the first valve and the second valve also being configured so that the flow paths of the first feed stream and the effluent stream are closed during production of a concentrate stream wherein the desalination system comprises an EDI apparatus in fluid communication with the at least one desalination cell for further processing of an effluent stream from the at least one desalination cell, wherein the EDI apparatus comprises an anode and a cathode and a plurality of alternating anion and cation exchange membranes disposed between the anode and the cathode to form a plurality of alternating dilute and concentrate channels between the anode and the cathode, and wherein the fluid communication between the desalination cell and the EDI apparatus is arranged such that the effluent stream from the desalination apparatus is introduced into the dilute channels, and wherein an input stream from a liquid source is introduced into the concentrate channels to carry removed target ions from the respective dilute channels out of the EDI apparatus so as to produce a concentrate fluid. at least one desalination cell comprising: first and second electrodes (22, 23); an anion exchange layer and a cation ion exchange layer disposed on the respective first and second electrodes; a spacer disposed between the first and second electrodes (22, 23); and ion exchange resin disposed between the first and second electrodes (22, 23);wherein the ion exchange resin comprises a mixture of anion exchange resin beads and cation exchange resin beads, the proportion of volumes of the anion exchange resin beads and the cation exchange resin beads being 1:1; first and second electrodes (22, 23); an anion exchange layer and a cation ion exchange layer disposed on the respective first and second electrodes; a spacer disposed between the first and second electrodes (22, 23); and ion exchange resin disposed between the first and second electrodes (22, 23);wherein the ion exchange resin comprises a mixture of anion exchange resin beads and cation exchange resin beads, the proportion of volumes of the anion exchange resin beads and the cation exchange resin beads being 1:1; the first valve and the second valve being configured so that the flow paths of the second feed stream and the concentrate stream are closed during removal of charged species or target ions, the first valve and the second valve also being configured so that the flow paths of the first feed stream and the effluent stream are closed during production of a concentrate stream wherein the EDI apparatus comprises an anode and a cathode and a plurality of alternating anion and cation exchange membranes disposed between the anode and the cathode to form a plurality of alternating dilute and concentrate channels between the anode and the cathode, and wherein the fluid communication between the desalination cell and the EDI apparatus is arranged such that the effluent stream from the desalination apparatus is introduced into the dilute channels, and