Milk bags are plastic bags that hold milk. They are usually stored in a pitcher or jug with one of the corners cut off to allow for pouring. A typical milk bag contains approximately 1 litres of milk. Popularity Milk bags are common in several countries and regions of the world, including Canada. They were also common in Bulgaria and other Balkan countries during the Soviet bloc period, but their popularity diminished after 1989. Declining popularity in this region is attributed to the lower shelf appeal of the milk bags compared to others emerging at the time such as Tetra Pak and pl...