I haven't stayed at the Hard Rock in many years, but at the time I found the gift shop to be really lacking in terms of personal care items. I don't remember the water or distilled water situation. You might ask over on the Universal board.
If you are going to Hard Rock first, how are you getting from airport to hotel? If you use a towncar, you can request a grocery store stop.
But PPs are pretty confident that it will be there.