That is correct... as for cleaning, pull the cap/spiggot, put in a few ounces of hot tap water, add a tablespoon of baking soda, replace the cap, give it a shake, let it sit overnight, empty and rinse. Your water bladder is ready to use.
If you're planning on long term storage, I'd add a few drops of bleach per gallon of water, and inspect now and then for leaks.

Troy