Distilled or Regular Water

And a lot depend on the tap water. A lot of water in the midwest is pretty full of minerals for example and the pH is not nertal and can be acidic. Not sure about you part of MN. Use of distilled just eliminates the issues; but a lot of tap water gets used in car with littel or no adverse problems.

My water here is from a well in hard rocks on a mountain and is about as pure are you can get; just dumb luck where we sunk the well.