Most sources show average Vital Lung Capacity (that's the term for the volume you speak about) at adult males slightly above 4 liters (~4.2 - 4.3 liter), other sources show up to 4.8l, but of course it depends very much on each individual so it can be anywhere between 3l (or possibly even less) to 10l (or possibly even more at some individuals). AFAIK, there are couple of athlets having the vital capacity 14 liters and possibly even more with packing.
EDIT: This may be a good start if you want to know more about this topic:
Lung volumes - Wikipedia, the free encyclopedia