Unlike the arrid regions, water is plentiful here but keeping a bottle in the truck in winter isn't possible as it freezes solid in a few hours and destroys the steel container it's in. I try to carry a full stainless steel bottle in and out with me, but sometimes it gets left behind. I have an empty SS bottle in the kit at all times, and a Katadyn filter. As I age, the importance of this piece of gear increases. It makes getting stuck in traffic more bearable. Fortunately, they come in olive green also...