1/? So how about a little off grid lesson time?
Lot of folks concentrate on little things- like toilet paper
But what are you doing for food and water? Think Maslows hierarchy and concentrate on the bottom 2. For those who need a refresher https://en.m.wikipedia.org/wiki/Maslow's_hierarchy_of_needs

2/ dont over complicate your planning. Do you have 4 walls & a roof? Good start. Move from there. Food is great but you can go days without food. Water not so much. Have ways to store water, filter water, purify water and boil water. Start by determining how much water You need

You can do that with a water intake calculator
Now using that daily intake figure how much water you need to keep on hand for 14 days. Do this for each person in your house, and addit together. Aint small is it? https://goodcalculators.com/water-intake-calculator/

I like to use 14 days for planning. Is it full on apocalypse planning? No. But it does fit in to most peoples budget a lot easier. Do 14 days. Then another 14. And another. Etc. Anyway now you have your water math. How do you store it? Use it? Obtain it?

5/ I suggest multiple methods. I use an Oasis with 5 gal water. Why? Its filtered. It stores. And when its empty I have a 5 gallon resealable container for water from other sources (creek, rain, etc). Also I can disinfect the water in it if need be.

6/ Recent headlines should tell you not to rely on your tap water forever. That said have a way to boil it. Coleman stove, propane burner, or campfire. Out of gas? Iodine can be used to purify water in a pinch. I keep a large store of it in hand as a result.

Brita filters are also handy but not foolproof. Still its better than nothing. Can use it to refill the 5 gal containers and seal the rubber lids back on with a little wax or silicone. All this steps will help in case of emergency.