Hardness is measured as ...

Hardness is measured as Calcium carbonate. Most countries do not regulate it because it is not a health risk, and probably beneficial. However, excessive hardness can affect potability and economics because it can build up in pipe and shorten the life of heaters. Some do not like the taste effect on coffee and tea. The USGS classifies hardness as follows:  soft, up to 60 mg/L, moderately hard 60-120, hard 120 -180, very hard above 180 mg/L. It can cause soap lathering and rinsing problems. That's why they invented detergents which have different chemistry than soaps. My water is in the moderately hard category and it is fine. I have never considered buying a water softener.