living in the uk I think it is even harder to justify stashing water, food and BOB's, we don't often have natural disasters here unlike in the States.
however I keep my BOB in the car with a small tent etc and at least 50 ltrs of bottled water in the house. food shopping I always buy a few bits extra, rice, pasta, dried veg and tinned meat, extra medicines, candles and anything else we might need.
I tell any body that asks that it is my emergency supplys for if something bad were to happen we would be prepared and could keep going for a few days.
I don't go into what I might think will happen or when, just that it is sensible to be prepared for the familys sake.

NOT A SINGLE PERSON HAS SAID THAT I AM MAD OR CRAZY? IN FACT SEVERAL HAVE STARTED TO DO THE SAME.