There are many ways to do water depending on your situation. You can buy a space saving bath tub water bag to fill when the power goes out.
Bottled water is good for medical, cooking and bartering. Gallons of water would be more practical to store. For houses with a basement, garage, schools and churches. I recommend 55 gallon drum's full of water and a 12 volt or hand crank pump or caged water tanks.
Buy Apple Juice, Ice Tea and soft drinks in gallon, half gallon and 2 liter sizes. Use these empty containers to store water. Set a goal of having 300 of these.