It would seem that Rowenta can't decide what should be used either. One person's directions will say only tap water, another's will say only distilled and mine says to use a combination of both. It appears to be a guess-what. My daughter has had two, both of which started leaking after a time. She bought me one and it said to use both, so that is what I do and so far it has been fine, but knowing what has happened to most, I now use a spray bottle most of the time, just in case.