Depends on the instructions and usage level in my opinion. My Rowenta says to use tap water but there are other model Rowentas that specify distilled. I purposely looked for one that wanted tap water. It says to empty after each use. When I was working and ironing clothes every day (just because I'm really anal about that) I never bothered. And now on the odd occasion that I do iron clothing I usually go through the entire tank so it's not much of an issue. Never have had an issue with mine leaking. My EuroPro requires distilled water. It, too, says to empty after each use. This is the one I typically use for quilting and I usually go through at least 1-3 entire tanks depending on how much time I have to sew that day so don't worry about it with that one either. Never had a problem with it either. My only issue with that one now is the cord wearing coming from the base of the iron. Guess it's time to get DH to re-wire that!