Send us Fan Mail If you had to stay home for seven days with no reliable tap water, would you feel prepared or trapped? We start our new Build Your Ark series with the most urgent “tenant” of preparedness: water. I lay out a realistic plan for building a solid one-week supply, why that one week buys you time and clear thinking, and how to calculate the minimum you need (plus the buffers that keep “minimum” from turning into painful rationing). From there, we get into the unglamorous details ...