Described herein are a method and system for desalinating saltwater using concentration difference energy. A “five stream” dialytic stack is described that can be used to desalinate saltwater at a relatively high recovery ratio. The dialytic stack may include, for example, one or more drive cells having a paired concentrate and a diluent-c chamber in ionic communication with a product chamber that is adjacent to an anion and a cation discharge chamber each filled with diluent-p. The drive cell applies a drive voltage across the product chamber, and when the drive voltage exceeds a desalination voltage of the product chamber, the saltwater in the product chamber is desalinated. The diluent-p may be at a lower ionic concentration than the diluent-c, which may be at a lower concentration than the concentrate. The relatively high concentrations of the concentrate and the diluent-c facilitate a relatively high recovery ratio, while the relatively low concentration of the diluent-p facilitates a relatively low desalination voltage. The dialytic stack may accept brine discharged from a first desalination plant and may use this brine as a source of the concentrate, diluent-c, or diluent-p. Alternatively, the dialytic stack may accept the brine as saltwater to be desalinated, and may then output desalinated brine back to the first desalination plant for further desalination. Processing the brine in the dialytic stack may decrease its volume, decreasing costs associated with treating or otherwise disposing of the brine.