A hydro-thermal exchange unit (HTEU) for desalinating feed water in accordance with a humidification-dehumidification includes feed water, fresh water and gas conduit circuits for transporting feed water, fresh water, and gas, respectively. The unit also includes an evaporator through which a portion of the feed water conduit and the gas conduit pass. The evaporator causes evaporation of a portion of the feed water to produce vapor that is transported through the gas conduit. The unit also includes a condenser through which a portion of the gas conduit and the fresh water conduit pass. The condenser has input and output ports for coupling the gas and fresh water conduit circuits. The condenser extracts moisture from the vapor transported therethrough by the gas conduit. The extracted moisture is discharged through the fresh water conduit. The unit also includes a heat exchanger through which a portion of the fresh water conduit and the feed water conduit pass to thereby extract residual heat from the fresh water such that the residual heat heats the feed water.