Data's positronic brain is similar enough to a humanoid brain for the polywater to have a similar effect.
In ST:TNG "Deja Q", Data makes reference to having "bio-functions". Whether that refers to systems that approximate biological functions, or something else, is unclear; I guess we have to conclude that he has systems susceptible to, and similarly responsive to, the polywater virus. Soong probably wanted him to experience at least alcohol inebriation--and, in ST:TNG "Relics", Data was aware that Guinan kept what we ultimately learn is Aldebaran Whiskey, that Picard had given her, behind the bar in Ten Forward. He obviously has had some interest in the Human (and Klingon) experience of alcohol intoxication ProfessorTrek 07:48, August 8, 2011 (UTC)