Stored water is hardly ever a bad idea; but you can't feasibly store enough for any long term. Articulate what you're planning for: days of no power or weeks of no services at all?
If you're worried now about not being able to trust the government next year; ask yourself why you have been trusting them to this point? Whatever your opinion of them, government at all levels is made of people no better or worse than you, as subject to error and blind obedience.
id say 10g/day minimum and you might plan for 20g if anyone wants to wash hands. If you ever need it, you will be very glad for whatever you have. Even a couple one gallon jugs can make a power interruption or whatever much less stressful.
Rotate or otherwise pay attention to freshness if you want to drink it.
serious nuts do things like put 1,000gal underground cisterns in their water systems. and/or frequently drink from local water streams so as to maintain a tolerance for the local "wild" water.
If you're worried now about not being able to trust the government next year; ask yourself why you have been trusting them to this point? Whatever your opinion of them, government at all levels is made of people no better or worse than you, as subject to error and blind obedience.