Originally Posted by cashs_mom

They aren't. I use filtered water in my Oliso as per the instructions. I would like to say that I talked to an Oliso rep at Quilt Festival last year and she said not to use distilled water or tap water because it was harmful to the plastics (or something like that). I've noticed that all my newer appliances the use water called for filtered (not distilled or tap water). Older irons are fine with distilled but you might want to check with the manufacturer before using it on a newer iron.