A local water quality store told me that Hardness of my tap water times 17 will tell me about the TDS. Is this true? My Hardness is 23. So 23 x 17 = 391 is this good or bad?
That's not a hard & fast rule. You can have high TDS with low carbonate and visa-versa. Perhaps that's true for your area though. A TDS meter will give you a better idea.
