If there's a nuclear or bioterrorism attack in your area, the food outside the door may become compromised. Better safe than sorry - I'd plan to stock as much food AND water as possible in a secure location.
If it's nuke I'm ground zero & that's a given. I would not be able to out run the initial blast much less the fallout. I'm less than 15 miles downwind. BIO? I keep at least a month of can food and my water supply is a 180 foot well. It can pour down rain for days and I get no surface water. I also have the water that would be in my 85 gallon tank on the pump.