I am very happy that my family (at least my kids anyway) are BIG TIME milk drinkers! We keep lots of milk on hand (thank heaven for our extra fridge downstairs!) and usually some pre-made chocolate milk (as a treat for the kids with the occasional dinner).
When I say "lots" of milk I do mean it. We are buying milk basically every week nowadays. And we buy 4-6 gallons at a time. Yes, we are close to about a gallon a day as a family (it is definitely over a gallon if you factor in the chocolate milk). That works out to about 1 gallon per person per week (Karen doesn't drink much at all if you're doing the math at home and questioning my calculation abilities).
I'm curious though ... is that "A LOT" or is that just about right?! Let me know your experience and family size. I do fear that when the kids hit the teenage years we may need a third fridge! YIKES !!! :)