A non-alcoholic drink that Leonard McCoy orders in an Earth spaceport bar in Star Trek III: The Search for Spock while trying to charter a ship to Genesis.
Altair water is a beverage ordered by Doctor McCoy in the film Star Trek III: The Search for Spock, set in 2285.
Carrying Spock's katra and behaving ever more erratically, McCoy goes to a crowded bar on Earth to meet a long-eared alien pilot and hire passage to the forbidden Genesis planet. When the waitress, who knows him as a regular, asks what he will have, he asks for Altair water, which surprises her since it is not his usual order.
The negotiation goes badly. McCoy talks too loudly about Genesis, a Federation security agent intervenes, and the doctor's attempt at a Vulcan nerve pinch fails. He is locked up until Kirk and Sulu break him out to steal the Enterprise.