Is that true for people on a well, and not on city water?? What about access to creek water than can be made drinkable??
Can you get the water out of the well when the power is out? Most well pumps take 220V electricity, most generators can run one no problem. Hand pumps will lift 30’ or so.
Not difficult to setup if done in advance. Plus drilling your own well (for emergency use, of course) is not that big a deal. Plans are on the net to drill your own well using garden hoses and PVC pipe. Won’t work everywhere,m but worth researching.
Creek water can be made potable, but must be set up in advance, and treatment methods verified. Water borne disease is not good when in survival mode.
How will the creek water get to the house? You will get 1 or 2 flushes from a 5 gal bucket. It gets old fast toting those uphill.
How are you going to operate your well pump with no electricity? Your water table is probably too,low for a hand pump (not enough suction head)
If you have an electric generator, how long is your fuel supply going to last? Do you store 500 gal,of fuel? 1,000 gal? 10,000 gal?
How do you keep it from going bad?
You can buy them ready made and there are even some DIY sites on the net describing how to make your own.
Here is one source:
https://www.lehmans.com/p-1384-lehmans-own-galvanized-well-bucket.aspx?show=all