A multi-channel apparatus through which saline water flows continuously contains two separate series of channelways defined by porous membranes. The membranes have pore sizes such that a wide variety of dissolved ions can pass through them. Electrodes or capacitors suitable for attracting dissolved ions are provided within each of the channels in one of the sets of water channelways ("the concentrate channelways"). Ions are concentrated within the series of channelways in which the electrodes or capacitors are provided by applying electrically attractive force in order to capture, concentrate, and remove the dissolved ions from the other series of deionized channelways ("the deionization channelways"). Ions are captured from both sets of channelways and concentrated in the concentrate channels. The concentrate and deionized water streams flow continuously through their respective series of channelways and are removed from the apparatus separately to keep the concentrate and deionized water from mixing. Two streams of water exit from the apparatus. None of the deionized product water is used for flushing ion concentrates.