According to the American Red Cross (ARC), Americans at a minimum should prepare an evacuation kit that includes among other things a three day supply of food and water for each member of the household. Be sure to take into consideration needs of the disabled, elderly, or very young in your home as well as any pets you will be taking with you. Remember Red Cross and FEMA shelters will likely not allow animals inside.
For a kit to be kept in the home for a ‘shelter-in-place’ type of emergency, the ARC and FEMA both advise citizens to equip their homes for a two week emergency. Store two weeks worth of food and water and remember medications as well. FEMA has advised that in the event of a pandemic flu or other contagion it may be necessary for citizens to stay in their homes for up to two weeks.
Visit the following websites for details on ways you can prepare. Those on a budget shouldn't despair. Just a small allotment of money every month will get you where you need to be in no time.