Why does drinking alcohol have to be an imposition? It is a decision and there is nothing wrong with not wanting to drink even if others are doing it. Those who turn away because of something like that simply do not deserve to have you by their side, if they are not able to respect something as normal as not wanting to consume alcohol.
The truth is that I drink very little, the whole year can pass without me drinking alcohol, because it is not a habit that I have at home and I don't go out much. Sometimes when I go out with my friends, I drink, but none of them force me to drink or bother me if I don't want to, it's called respect.
It's just unfortunate that people could stoop so low with pressurizing their friends to take to a habit they do not find appropriate.