A desalination system including: a partitioned container having upstream and downstream compartments divided by a movable partition, a first inlet port at an upstream end, and a second inlet port and an outlet port at the downstream end; a membrane container housing a cross-flow semipermeable membrane dividing the membrane container into saline and desalinated compartments, the saline compartment including first and second cross-flow ports, the desalinated compartment including a desalinated water outlet port; a feed pump connected to the first inlet port; a recharge pump having an inlet connected to the second cross-flow port and an outlet connected to the second inlet port; a main valve connected between the outlet port and the first cross-flow port; a bypass valve connecting the inlet port to the second cross-flow port and the recharge pump inlet; and a purge valve connecting the first cross-flow port and the main valve to a purge port.