I just buy the Wally World distilled water in the gallon jugs, my well water is crappy so I drink and cook with the good stuff. About a year on the expiration dates, and I assume they will still be drinkable after that. They get rotated out during normal use anyway. For washing/flushing water the water heater has 60 gallons in it, and the well pressure tank holds about 20. For longer term outages all I need to do is wire in a generator to the well pump.
If you're gonna go with canned water, why not just buy the cheap store brand pop. Diet if the sugar bothers you, you can get tea, lemonade, etc if the carbonation is unwanted. Probably cheaper than actual canned water. Seltzer water used for cooking will pretty much release all the CO2 during the cooking process, just pouring it between two glasses several times will make it "go flat" as well. Check at boating stores, there are several brands of "survival water" that come packed in either "juice box" or bag type containers.