chemical precipitation is ...

chemical precipitation is also an option.  This would require addition of lime to say pH 11 to precipitate the temporary hardness (Ca and Mg).  To precipitate the permanent hardness would require addition of barium carbonate (precipitate the sulphates as BaSO4).  Barium carbonate is expensive, but could be recovered and re-used.  The fluoride levels are not a problem at 1.4 ppm.  sodium and chloride cannot be removed through chemical precipitation, but could use a other alternatives to RO such as ion exchange (on a side stream to just reduce sufficient to blend to WHO standard).  As others have said though, RO is probably the optimum solution, and perhaps the focus should be on ways to treat the RO reject??