I'm not a hardcore prepper; but I do maintain an emergency water supply stored in the crawl space. I use some 5-gallon Military Water Cans (about $25 each) supplemented with re-used 1-gallon distilled water bottles.
Here is a useful reference on how to do this safely:
Emergency Water Supply Preparation
Ahh, I use sealed, 5-gal. bpa-free Culligan water bottles. Keep 30 gal.s on hand even tho I have a well and generator.