Abstract: A renal dialysis concentrate delivery system comprising at least two renal dialysis concentrate reservoirs, first supply valve means and supply conduit means. First supply conduit means connecting a first concentrate reservoir to the first supply valve means. Second supply conduit means connecting a second concentrate reservoir to the first supply valve means. Concentrate pump means operatively associated with the supply conduit means. Conduit means for transporting the concentrate toward a renal dialysis machine. Return conduit means for returning concentrate to the concentrate reservoirs. The first supply valve means may be a three-way valve.The return conduit means preferably includes a second three-way valve. Valve control means coordinate the positioning of the three-way valves so as to provide a first position wherein both valves are in communication with a first concentrate reservoir, and a second position wherein both valves are in communication with a second concentrate reservoir.