I take it you are talking about the biggest survival kit you carry on your person. If you do not carrying it then it is of no value. I also assume you are not talking about backpacking because then you are already carrying some of the best survival gear there is. That leaves hiking and day packs or fanny packs. I carry a CamelBack. I use the BlowFish, it holds 100 oz (3.13 quarts) of water and has lots of room for my survival stuff. I use the web area in the back as a trash bag while I am hiking with my family. I have 4 boys, 10, 10, 13, and 20.
_________________________
Thermo-regulate, hydrate and communicate.