Im in the process of making up some BOB bags ,in ours i will have 1 days water and then a clear collapseable vinal type water container that holds aprox 3 gallons , that is deflated in my pack, for when you get to an area that you will be staying at you have the ability to purify larger amounts of water at a time, but have some thing that compresses fairly small , i have 1 of these in my wife and my BOB bags, because there is 4 of us to get water ready for.<br>Yukon