Apparatus for evaporating waste water having dissolved solids therein comprising a holding tank having an inlet for receiving waste water, a submerged combustion chamber with burner suspended within the holding tank, the submerged combustion chamber having a plurality of vertical slots defined therein near a bottom thereof which span a substantial portion of a height of the submerged combustion chamber, a blower connected to provide air under positive pressure to the burner, and, a vent stack coupled to an upper portion of the holding tank for allowing water vapor to exit the holding tank.