I get the sense that the government would probably go out of it's way to discourage "stockpiling," if a true law was passed banning alcohol. You would probably be best served by buying bottles in a large quantity of purchases of small amounts spread out between as many stores as possible. A barrel purchase would probably draw unnecessary eyes upon you if consumption or possession was banned.
Portwood, I'm by no means a prohibition history buff, but I don't think consumption was ever illegal. I think it mainly focused on the manufacture, selling, and transportation of alcohol.