The iron problem is stated here http://www.apug.org/forums/forum37/24281-xtol-4.html . Look at post #34.
I actually distil my own water. The stuff you buy in the drug stores is probably just filtered. Judging by the sludge left behind at the bottom of my distiller, I trust mine.
When I make my xtol (mytol), it uses salicytic acid to combat the iron problem. There is stuff in the original xtol too, but time will usually kill the 5l of xtol. I think it was a big mistake when Kodak removed the 1l from the shelves.
But like I said in a previous post, replenished did not spoil for me. It may be an option if throwing the unused stuff makes your blood curdle. I preferred the look of replenished anyway.