well water or hard water
Hard water is what we have a lot of here in Cali.. its pretty much a high concentration of calcium in the water. Which in turns leaves deposits. IE Waterspots, that crap on your shower door, ect... It's not harmfull, just a nusance.
Well water? Couldnt tell ya, but my guess is that it would be more pure than tap water so in turn better for you/your truck, allthough it hasnt been "cleaned" in the modern sense...
Anybody feel free to corect me..