I recently organized a group buy for flour. On Wednesday I unloaded a half a ton of flour for distribution to bakers in Columbus! The flour came to us in double walled paper bags holding fifty pounds of flour each. Fifty pounds of flour is a lot for even the most prolific home bakers so proper storage is a must.
Flour will spoil if it gets too moist. Bugs love to nest in it. Mice and other rodents are attracted to flour too.
The first step in flour storage is to put it in the freezer for at least two days. It can stay right in the paper bag. The purpose of freezing is to kill any insect eggs that might have found their way into the flour.
We are fortunate to have a deep freezer but you could do this in batches in a refrigerator freezer too. If you don't need the storage space you can keep the flour in the freezer indefinitely.
Next, portion the flour into airtight opaque storage containers. Keeping air and light out will retain freshness. We use bulk bins purchased from Wasserstrom restaurant supply. Foodsafe five gallon buckets with tight fitting lids are another good choice.
Store your bulk bins in a cool dry place. Our basement stays dry so we keep them there. Other alternatives include a cool closet or root cellar.
Portion a few week's worth of flour into a storage container to keep where you bake. We keep a large scoop in the bulk bin for this purpose. We keep about three pounds of bread flour and white whole wheat in the kitchen plus a smaller portion of all purpose.
Finally, examine the bins regularly. Clean any spills from around the area to keep pests at bay.
Our flour has remained fresh in this manner for up to twelve months.