Abstract: Based on the capacity characteristics of electrical double layer, a new separation method--charge concentration is proposed, and a preliminary experimental study is made. The separation unit is a column packed with powdered activated carbon. Two disc electrodes with some well - distributed apertures are placed separately on the top and under the bottom of the activated carbon. Hard water is fed continuously from the top of the column and the conductivity of the effluent from the bottom is measured with a conductometer. The measured results indicate that ions in water can be removed by applying direct current to the electrodes and then a concentrated solution can be obtained by turning off the current.