Patent ID: 8470152

Claim:
A method for durably softening water, the method comprising: collecting a stream of clean water at a flow rate of F 1 , while applying a charge voltage of between about 0.5V and about 1.0V between a cathode current collector and an anode current collector for a first period of time, T 1 , wherein a cell comprises the cathode current collector, a first electrode capable of adsorbing or absorbing ions, a cation selective membrane, a spacer, an ion selective membrane, a second electrode capable of adsorbing or absorbing ions, and the anode current collector; and collecting a stream of waste water at a second flow rate, F 2 , while applying a discharge voltage between about −1.5 and about −1.0 V between the cathode current collector and the anode current collector for a second period of time, T 2 , such that (T 1 )(F 1 )/[(T 1 )(F 1 )+(T 2 )(F 2 )] is greater than or equal to about 0.5, wherein the magnitude of the charge voltage is lower than the magnitude of the discharge voltage.