I read an article recently by a man who hiked the Appalachian trail. He made a really great point about pack weight. There is a relationship between how much your pack weighs and how much ground you can cover in a day. The heavier your pack, the more energy goes into carrying the pack rather than moving forward. I thought I was the only one who kept my actual GO bag under 20 lbs, but I guess not. Mine is light because I wrecked my back running for many years in the Army, not because I'm a genius. The author of the linked post, however, could be the genius.
When you make your emergency plans, leaving on foot is usually a last resort, but it should be in your plans. Your first and/or second level of preparation should be suitable for easy adaptation to leaving on foot. I include both levels because some people have a first level of preparation, called 'Every Day Carry' (EDC) that usually fits in their pocket or purse. It may include simple items like a small lighter, a pocket knife, a Mylar blanket and something to disinfect and hold water --possibly even a Ziploc bag and one disinfectant tablet. The EDC should be sufficient to get you to your next level of preparedness, which would either be home, your desk at work, your GO bag (other acronyms for this bag include GOOD bag or BOB) or whatever you regularly carry in your car. Remember that your car kit may become your GO bag if traffic or other conditions render your car useless. Always have a day pack with your car gear, even one that is not the greatest, in case you need to pack up your car kit and leave on foot. My next level up includes a plastic box with more food and a small duffel bag with more clothing and a sleeping bag. If it comes time to abandon the car, I can grab another layer of clothes and maybe a few more food pouches for the next meal only and head out with the light pack.
So how do you do this -- keep to 20 lbs or less AND have some redundancy in the most important items? First a little aside on redundancy. Redundancy means have at least 2 ways to cover the most important basics. An example is how to provide fire. I keep a small Bic lighter, a waterproof match case with strike anywhere matches, a small plastic magnifying glass (which has a lot of other uses) and a fire steel. Somewhere in there is a method for virtually any conditions I may encounter. I consider fire to be a preparedness imperative, so I go a little overboard. I also have 4 ways to purify water -- here in the desert southwest, if you are lucky enough to find standing water, it's probably disgusting stuff, so more ways are better. The main way to keep the pack light is to miniaturize and remember that this pack is for getting out of the immediate danger. You don't need a whole box of tissue, but a pocket pack may be useful. You don't need an entire wardrobe, but clean socks and undies may be a welcomed relief. You should have enough to keep you going for 72 to 96 hours. Not your whole family or neighborhood, and not forever. It is a supplement to what you are wearing. If you are at work in a suit or high heels, you should also have a change of clothes and shoes in your desk or car before venturing out with your GO bag.
There are lots of inexpensive but reliable products that are small. The Princeton Tec lights at Sierra Trading Post are small and inexpensive (especially when on sale), but powerful enough and are available in white and red light. I also keep a small, cheap solar flashlight that has a caribiner clip, so it can be charging while I walk when I hook it to my pack strap or back. You don't need the premium sleeping bag. One of the emergency bags could last you and are small and cheap. Instead of a huge tent, try one of these or get the heaviest (in mils) plastic drop cloth from Home Depot and some parachute cord. You can make your own wind and rain shelter for about 8 ounces.
Personal hygiene? Use Wisp toothettes or a pre-filled tooth brush. Include a small hotel soap and a few pre-moistened wipes. I have a small microfiber towel, which can do double duty as part of the 'keep warm' stuff when dry. Small Tupperwares (about 1.25 inches in diameter) of your meds, salt, sugar are smart to have. A change of socks and undies are good. Cash and ID are very important. A pocket knife and a spork, a metal canteen cup (Army surplus) and some food are also a good idea. Think BASICS, small and short duration.
For children, don't make it too austere. They may not be able to take their favorite quilt and stuffed animal, but include a small comfort item. If there is a light weight stuffed toy, especially one that can double as a pillow, throw it in for the little one. For an older child, a pack of cards for a game of Go-Fish or rummy may lighten the mood as you prepare to bed down. If you have an infant, you must research how to balance their sanitary requirements with weight -- cloth diapers and liners may be the answer, but technology has changed a lot since I last researched that one! You can wash a diaper and hang it on the back of your pack to dry while you walk if need be. Not so much with disposables.
I'm about to change from my 'summer' pack list to my 'winter' list. My pack will go from 16 lbs to about 19 to allow for extra warmth items and a few more calories.
What about your GO bag? Is it obese? Can you carry it for 10 hours? If so, how much ground can you cover? If you aren't an Army Ranger or super athlete, check your emergency GO bags for everyone in the family and see if any of them need to go on a diet!