They also expand in your stomach so you feel full. Be careful that you don't over-consume them because they are so high in calories. Drinkable water is of utmost importance. Most people can actually survive days without food, but your body will dehydrate without water, leading to organ failure and death. We take the abundance of water for granted when things are normal, but in an emergency it becomes critical.
Water is also useful for washing wounds and for sanitation.
Water can also be helpful if your car overheats. Because of the limited space in automobiles, storing water must be in small packages. You may have plenty of food and water, but if you're cold you'll feel miserable. Especially in the winter, warmth is a must for an auto 72 hour kit. If you get stranded on a desolate road or stuck in a snowstorm, you will be glad you have a source of warmth in your car.