Mikvah Water, take II

Tzemach sheds some light on the question of the Lubavitch Mikvah water. Before Y2K, Lubavitch wanted to reach out to 'foreign' tourists in Israel looking for a 'Jewish souvenir.' They decided to produce a pamphlet, and wanted to include a 'meaningful token' as well:

[T]he Rebbe’s "mikva water," water in which the Rebbe Melech HaMoshiach had toiveled, had recently been getting a lot of publicity; many stories were being told about the wonders and miracles it had brought to Jews and, l’havdil, non-Jews alike. In the end, the Rebbe’s "mikva water" was chosen.

(More here.)

How much of this water was still available in 2000? How long had it been bottled for, and how far back does this custom go? And is the water sold outside 770 by the random woman the Rebbe's? Enquiring minds want to know!