My mom always did that, too.
I just use our tap water or, since I sew in the attic bring a bottle of water upstairs with me and use that. I've been doing this for years without problem.

Same here and I used to have the brown spots issue with a previous iron, no problem now. We have a lot of calcium in our tap water so I never use that......we have a Brita filter in the fridge/freezer so I just drain a little to fill the iron as needed.