mpawelek brought up a good point, as did Bruce Peter. There are a number of factors here that everyone should consider. That's one of the reasons I always feel better when I tack on my "just my experience/$.02" disclaimers. Although I'm all in favor of softening water, that's based on MY experiences. I still want everyone to hear all the information that's out there.
The original thread was only about using it for detailing, but I will say that my wife and I both drink the softened water treated with the potassium chloride and water from the other softener that uses regular softener salt. There have been no health problems as a result of it (and I drink at least a gallon a day). BTW, we are EXTREMELY health conscious by most standards so any such problems would have come to our attention. None of our houseplants are suffering from it either. We debated having the drinking water run on a separate line (as at our old house) and decided against it after all the in-depth talking with our plumbing contractor. Our experiences have been similar to those of OutlawTitan, but that doesn't mean it'll work out that way for everyone. I will say that I'm surprised that mpawelek's father was "poisoned" by his softener (and I'm sure glad to hear he's OK!). I can't help but wonder if his softener was working properly. Again, the "salt-stuff" should be rinsed off the media before the water you actually use passes through said media (we use an EXCEPTIONALLY long rinse cycle to make sure of it). Old softeners WERE notorious for killing plants (and I saw it happen myself), but I was told that's a thing of the past. HMMM...:nixweiss Could this be an application/unit specific sort of thing? If the potassium got through to mpawelek's father, then salt could've gotten through to a car. Keep posting any info you have, folks!