Well, I guess I'll throw my 2cents into the ring too...
On the sub we would distill seawater, boiling it and condensing the steam, thus purifying it for drinking by removing all the various minerals and whatnot.
THEN we would pass the distilled water through a de-ionizer (a resin bed to remove the remaining ions).
I imagine civilian world DI water is produced in a similar fashion. Otherwise you would use up your DI resin fairly quickly, depending on how "dirty" your supply water is.
So your distilled water is the first "filtration" process, then deionization is the "fine filtering", so to speak.
However, the DI will strip ions from whatever you put it next to. So once you pour it into / mix it with anything, it is no longer "de-ionized".
:beer:
Thank you for that additional info. By the way, where was your sub stationed?