Your Bag
Finding Your Perfect Bag
What's the best bag to have in an emergency? The one you have with you. As we make suggestions on what to look for, please remember that something is better than nothing. Even if your kit is contained in nothing more than some garbage bags and ziplocs, having something is always better than having nothing. With that in mind, let's continue.
The bag is your keystone of your 72-hour kit. It has to be able to contain everything you need, survive at least a moderate amount of abuse, and be "workable." (Meaning you can carry it and use it without difficulty.)
We've seen some lists that talk about using Rubbermaid bins, rolling luggage, etc. There might be a good use case for this (such as building a shelter-in-place kit for bins or perhaps a kit intended to be kept in a car or camper). Our experience, however, is that the best kit is one you can carry.
Consider something like a flood or earthquake. There's likely to be lots of debris and other hindrances just getting down the street. Something that's awkward to carry (a bin) or has wheels is going to be mighty hard if you have to lug them over a thousand tree branches on your way to a designated gathering point. This is doubly true if you find yourself in the backwoods or anywhere off-road.
Additionally, shoulder bags or totes can quickly tire you out if having to carry them by hand. Even a bag as light as 10 pounds or less can become very burdensome if you're having to drag it around like a tote. (Been there, done that.)
These reasons are why we suggest backpacks where possible.
Keep in mind that while we suggest backpacks, if you're limited financially or otherwise to carrying your items in a bin or tote (or even garbage bags!) that the best bag to have in an emergency is the one you have with you. Take these suggestions to heart, but be ready to adapt to your needs.
The Gist
An ideal backpack will be one that is light, is well suited to your size, is durable, and has lots of compartments or straps for stashing things. You might even consider a MOLLE system pack. (We'll get to this one later.) Ideally you'd also find one that's waterproof since "when it rains, it pours". (However, a good poncho would fit over you AND your backpack, so that's something to consider.)
Material
Try to find a backpack that's made out of a durable nylon or even a lightweight canvas. Most modern backpacks fit this bill. Technologies such as "rip stop" nylon will be even more durable. Canvas is great for durability, but is a good bit heavier and you'll need to make sure it's been treated to be water resistant.
Size and Fit
Try to find a bag that's suited to your frame or (better) adjustable. Bags that are too large or to small both present issues with comfort when carrying for a long time. Ideally your bag will have a well-padded hip strap to support most of the weight so it's not weighing down your shoulders which can be very tiring. That having been said, if your kit is light enough, the hip belt may not even be necessary. As we said in our getting started comments, plan around what you think you'll need. If there is a particular style that you like, see if you know someone who has one, borrow it and load it with 30 pounds of stuff and see how it feels walking around for a while.
Pockets, pockets, pockets!
One of the biggest things to look for in your bag will be lots of compartments. The more, the merrier. Ideally you'll be able to organize all your items into their own compartment so that you can go straight to the compartment that contains the category if item you need. (For example, a compartment that deals with just things pertaining to fire, or just items for shelter, etc.) A pack with multiple external pockets is ideal since you can quickly get at select items (like a water filter) without having to even open the main compartment.
At the end of the day, you just don't want to have to spend too much time looking for things. (Or worse, have to completely empty your bag to get at something at the bottom.) Fortunately, there are ways to mitigate this even if you have a single compartment backpack.
Pouches - Not just for kangaroos.
In lieu of pockets and compartments, we've found that something like these zippered pouches are fantastic for keeping things organized inside your kit. We keep our fire starting gear in one, hygeine supplies in another, etc. They're very durable and are a great way to get things divided nicely. As an added bonus, you can clip them to the outside of your pack if you'd like. Don't want to pay for zippered pouches? No worries, grab some ziploc bags instead! You can use something like these cloth labels to note what's inside the bag so you don't have to play the guessing game.
"Molly, who?"
MOLLE packs (pronounced "Molly") are those packs that you see so often in military pictures. They use a special, standardized loop system that is geared to work with many, many accessories that can just attach easily to the outside of your pack. These can give you endless customization options.
While we like these packs in practice, it's worth noting that the one thing we don't like about them is that they tend to draw attention to the wearer, which might not be the best idea in an emergency. You're far more likely to get noticed in one of these packs than you are in a non-descript, standard backpack. Still, for the ultimate in customizability, you can't go wrong with one of these. As an added bonus, they're usually quite durable. Usually.
Zip or Clip?
While most backpacks utilize zippers (nearly all do these days) you can still find some packs using straps or cinches to secure their contents. When you're selecting your pack, watch out for existing zipper problems and check to see if the zippers are smooth. If they break during use, you're gonna have a hard time.
Many canvas backpacks offer leather or webbing to secure their flaps, which are nice since they're less likely to fail. (Unless poorly sewn.) These come at that weight trade-off again. We won't say which is better, these are just some things to think about as you're selecting a pack.
These cost how much?!
The reality is that everyone who can carry their own pack in an emergency, should. Unfortunately this means that for larger families, this ends up being a lot of packs you might have to buy. Consider some of these options for saving some money:
Goodwill/Deseret Industries/Thrift Stores
Garage Sales
Military Surplus Stores & Websites (Be careful with this one. Some "surplus" stores sell second-rate items at first-rate prices. But, there are others where you can really get a great deal on a slightly weathered pack.)
Online Classifieds
Social Marketplaces & Neighborhood Sites
Ebay (I've gotten some great military surplus bags here that needed a little TLC then gave a lot of good service)
Drawstring Backpacks (These are those backpacks that just have lightweight ropes for straps that often come as hand-outs with freebies from conventions or some stores. They may not be great for an adult, but for a toddler they might be all you need.)
Homemade - A little research will offer multiple ideas for how to make your own lightweight backpack if you're crafty. (Especially true for those drawstring packs.)