Simultaneous source-sink flow, or radial counterflow, is driven by a centrifugal pump disposed within a casing. Radially outward source flow of brine goes into a shrouding tank and concentrates while a radially inward sink flow of fresh water flows back over the pump to axial extraction. An axial pump drives sink flow and axial extraction. Convergent sink flow passes under an inductor to an axial exhaust port. Induced viscosity and inductive repulsion hinder the passage of brine in sink flow, so only fresh water can reach the axial exhaust port. Crystallization of scale-forming salts is aided by Joule heating from the inductor. Solvent and gases are continuously axially extracted in sink flow, favoring crystallization. Sodium chloride is cooled and crystallized in the shrouding tank. Brine comprising other salts flows out of the tank to treatment by suitable means. Thus brine is separated into fresh water, crystallized salt, and concentrated brine.