A species of ions in the feed of an ion exchanger present in the effluent. Leakages allow the movement of ions to flow across the cell membrane and through their gradients to a lower concentration, which can help preserve a stagnant potential for the resting membrane due to the combined efforts of the ion pumping and ion leakage. Leakage arises in ion exchangers when the regeneration process is not complete within the exchanger bed. The ions that are still existing on the resins after the regeneration process eventually enter into the solution during later cycles.