Water Storage

Hi, I'm new to the site and new to prepping. I'm a military spouse based outside of Ft Bragg, NC and full of millions of questions, but just one for now. We live on base housing off post and there's been a lot of electrical and water shut offs with no warning. Being in the military, money is tight. Can I store water for household cleaning and toilet flushing in a cleaned, heavy duty, 2 gallon detergent container? And how long would the water keep without having to refill?
We have 4 special needs children so we basically need to stay put unless it's absolutely necessary to get out.