Preparing for the end times. Faraday cage or water tank?

Preparing for the end times. Faraday cage that will have no use as there will be no electricity or a water tank that can keep you alive for months to a year? Freeze dried foods at almost 3 times the price of canned goods that still needs water added to be made edible. Oops, but oh no. Your Faraday cage does not hold 5000 liters of water so your screwed. And no one to call as there is no more signal.