When you cycle your water storage, what do you do with the "old" water?

I have about 6L of filtered tap water in bottles in the fridge. I cycle through those constantly through drinking and refilling.

I also have a 6G plastic "jerry can" in the closet. I'm looking for suggestions for the old water when I cycle that container. I'd rather not just pour it down the drain.

The only thing I've come up with is pour it on the landscaping outside.