Hi Ken, the salt content, fluoride, dissolved minerals will kill the roots and leaves. But some carnivores can tolerate tap water, my Pinguiculas don't mind. But the others I use distilled water. I save some rain water if we ever get any collectible amount, but it is too infrequent here in our area, so distilled water it is.
The vendor were I got my Nepenthes says his Nepenthes tolerates tap water too, but tap water varies from area to area, so I am sticking to distilled water for my new addition.
