If you purchase Juice buckets to make wine, you end up with a new primary. The bucket the juice comes in is typically a 6 1/2 gallon food grade bucket with a breather valve. remove the rubber valve, drill out the opening to fit a rubber grommet for an airlock.
I now have 9 primaries by doing just that, but never have more than 4 going at one time.
As mentioned earlier by others, you can use the primary for both, but I prefer to mark my primaries for beer or wine only.
Oh! by the way....... These juice buckets also make great brine tanks for fresh hams and other special meat creations.