Simply put, water is liquid life. Having it will keep you alive longer than any food, and conversely, not having it will kill you quicker than starvation. Another really important thing to consider is that you will use a significant amount of water in cooking (especially if you will be reconstituting anything dehydrated). If you really want to make sure you have this base covered, you need to have some water stored (multiple sized containers), a means of resupplying (rainwater collection, well, stream, nearby pond, lake, etc), and reliable means of purification (I recommend the Lifestraw or Aquamira Frontier Pro for your bug out bag, and the Berkey for your home). If possible, a bathtub water storage bladder like a WaterBob gives you the capacity to store 100 extra gallons, although you do need a few minutes notice to get it out and set up.