bottled drinking water
water filters with tanks like zero water
flash lights, fresh batteries
propane tank and camp stove
mylar blankets
fire wood
matches, lighters, fire starters
medicines you need daily and general antiseptic cleaners, bandages, first aid items
keep your car's gas tank full. If possible safely store a 5 gal. jerry can with gas.
canned goods including soups, spam, pasta, vegetables, fruits, things that keep without refrigeration
yes, toilet paper
soap, bodywash.
water for flushing toilets, washing, cooking Don't forget your hot water tank as a source.
solar powered battery charger for cell phones.
guns and ammo for defense, hunting
photograph all important papers and documents in case you can't grab them to take with you and backup if possible.
backup your computers to small portable drives.
fiat money might be worthless in a crisis. Always have some higher karat gold that can be accessed quickly if you need to move. Small gold coins, 18k or link chain that could be broken down into smaller links for trading. Stash in small coin in each shoe under the cushion.
A plan that you discuss with family and friends containing ways to contact each other if power and cell towers are out, rendezvous places should you need to move or bug out.
I would see after a couple of weeks, people taking matters into their own hands (after a specific 'event') with re=opening vital services (water tx plants, possibly electric) and running those without 'company authorization'. Also, I suspect that such a scenario has already been planned out by FEMA for re-starting vital services (medical, energy, nourishment to the masses) in the event of an EMP or other catastrophe. I don't see a Mad Max scenario except by a few people losing their sanity and going scorched Earth, by themselves, until someone else remedies that situation.
With regards to the list - I believe the most difficult supply to stockpile will be water. The water supply was disrupted at my house a few weeks ago for 3 days (water main break) and I took that as a test run to see how much water my household would need in an emergency. We went through more than I EVER dreamed in just drinking/cooking/teeth, dishwashing, and basic personal hygiene (whore's baths, flushing).- No clothes washed at all. Very eye-opening, and I, fortunately, didn't have to water the garden during that time at all (it rained one day).
Water is the last thing I would worry about where I live. You can drive much more than a mile without crossing a river or creek. You can get to the water table with just a shovel. Drilling a well is simple. It also rains a lot, so catching roof runoff is easy. You can actually put a catchment tank outside near one of your indoor commodes and flush the toilet directly with rainwater.
I don't water anything in the yard. If I don't mow, the yard becomes a jungle quickly.