Your local water utility will provide you a copy of their annual compliance report, which gives detailed test results and outlines in great detail what's in the water. Hardness of 5 is on the low side. I don't know if it is high enough to recommend a softener. Around here, our wate is 14, and a lot of people have a softener, most do not. I don't have one. I would want to know what is causing the odor.
I don't like whole-house charcoal filters, becuase they remove the chlorine and leave the inside piping vulnerable to "growth".
I wonder if point of use charcoal filters for the WM , shower, and kitchen sink would be practical?