allow beavers to drink out of river in emergency
link to a bit of discussion:
basically, if it's a choice between dying of thirst or drinking unpurified water, we should be able to at the cost of a penalty.
i'd say you'd have to be able to swim in the water to drink though.
some penalty ideas brought up (not exclusive): increased hunger (from diarrhea ), leaving a nasty trail behind them, move speed debuff, permanent debuff until medical beaver heals them.