Parallel desalting (PDS) includes a hybrid membrane softening (MS) system for de-mineralizing water for residential and commercial use. Parallel desalting produces "soft" water without the use of salt, or any other liquid chemical reagent normally used to carry out pH adjustment in industrial membrane and precipitation processes. The PDS process balances the operation of a RO (potable water) membrane unit with the operation of a tubular MF (wastewater) membrane unit, thereby providing a highly efficient and regenerative water treatment technology: (1) The optimum operation for the PDS system transforms roughly 90 percent of a potable, slightly brackish water supply into <50 mg/L TDS water with <1-grain (10 15 mg/L as calcium carbonate)--water hardness; and (2) The operation of the PDS system produces, in salinity terms, in a 100 percent reusable effluent for downstream recycling. Virtual prototype results suggest that with Colorado River Aqueduct source water (570 620 mg/L TDS and 16-grain water hardness), parallel desalting can produce an effluent with a TDS 40 70 mg/L lower than the originating supply (excluding TDS contributed directly by the particular type of use of the soft water).