www.aquaflex.net and www.nitro-pak.com have quite a variety of storage containers for long term water storage. I have been told that some plastics are not that good for water storage because they can begin to degrade, adding chemicals to the water. I don't have any expertise on this though.

I have one advantage living in NYC. I have a sailboat and if the problem is really long term, can sail up the Hudson, though I would have to sail quite a way before it changed from salt to fresh. (That is, assuming I can get to the boat before the looters do.).