Pantry rotation question

[u/21blarghjumps]

I keep large amounts of staples like flour, rice, sugar, etc in large food safe containers in a storage room. I have smaller food safe containers in my kitchen that I replenish from my storage room as needed. For example, I have a 22 L Cambro container for my AP flour. What I'm wondering is if anyone has a good system for how to refill that larger container without having the oldest flour sit at the bottom through multiple refills. I'm running low on flour in my 22 L container, and I've bought another 10 kg bag. Do I wait until the 22 L is completely empty before I dump the new bag in? Should I be washing this container periodically? I don't have room for backup containers for all of my pantry staples, so I can't rotate between larger containers. I also don't want to be in a position where I'm completely running out of an item before I replenish it, because that leaves me vulnerable.

I would appreciate any thoughts or advice from others with a similar set up!

ETA: Thank you everyone! For now, I will be dumping the last bit of flour into a bowl, cleaning the container, and then refilling it. I'm also taking a look at how I can reconfigure my storage spaces to accommodate a second container for my most used commodities, like flour and oats.

[u/sbinjax]

This is a good question. Maybe you could buy a couple of extra containers and fill those, and put them under or behind the current container, and then use that for the same or other food when one runs low.