This has been discussed in various forums including this one. Almost always there's a subtext to your question Dweste - that someone is comin for your 'excess supplies' simply because you have them and others need them. Confiscation, requisition, eminent domain, what have you - the spectre of local authority showing up and taking away your excess to help others. I have spent time studying a number of severe disasters, and there is no record that I can find of local authorities confiscating excess supplies from survivors, 'for the greater good.' More often there is on record instances of individuals donating what they have to help others, willingly, gladly. I think the concept of having a cache of supplies that others covet enough to come and take them posits a disaster far more severe than anyone actually has experienced.

You can't answer this question in isolation from actual disasters. So put yourself in one - take the American Samoa earthquake and tsunami. By itself its a very dire situation. They are very low on drinking water, there are a fair number of injured, things will get back to normal, but it will be slow. Plop me down in America Samoa, and my family would be well supplied for at least a few weeks. And given the rate of inflow of aid to the area, I could safely share some of what I have on hand with friends and neighbors. It has been hardest for the first 72 hours, with the next 72 hours seeing aid come in, and the next week intended to improve life and begin to get people back to 'normal.' For the first 3-5 days I would expect to expend much of my food and medical supplies for the greater good - that might include giving first aid, and feeding family, friends and neighbors, sharing what I have. 'Normal' for me means being generous with what I have to help others in my community, knowing that I'll have an opportunity to resupply in the near term. Soon after a disaster I would start to inventory and resupply.