If you're counting the water in your hot water tank, how often do you drain it? I drained the tank at my sister's home this past summer and had a hard time getting the "chunks" through the 10' hose. (And if you do have to use that water, don't forget to turn off the circuit breakers to the tank. If the power comes on before the tank refills, you won't have any hot water until you replace the heating elements that you've burned out.)
And if you're thinking of filling the bathtub, put the stopper in today and fill it with cold water. See how long it stays in there. You might get a surprise if the stopper leaks, and many do. And bathtub water won't be available in some cases. If an earthquake breaks the water main, forget it.
Sue