I use either hand to grab the water bottle.
My brakes are all switched too but I don't drink unless I have very clear road in front of me so I have time to react if I need to. Course I also ride alone 90% of the time so I don't know what I'd do in a group situation.
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"