In general, I would store plenty, more than you would contemplate backpacking. If you travel by vehicle, the weight is basically irrelevant and you won't have to scrimp. If you then have to hoof it, at least you have options and you can tank up before you start walking. Your physical and your mental capability declines rapidly when water supplies are inadequate.<br><br>What is inadequate? It will depend a lot on the season and local weather conditions - your needs can vary by a factor three (I have seen conditions where three gallons a day per person would be marginal, although probably enough). Even in the desert water requirements can vary from very high to minimal (winter, spring just after a major storm). You can always toss or leave behind what you don't need. If you are walking, your requirements will be much higher than if you are sedentary or driving.<br><br>Store water in smaller containers - one to two liters are about right. They can be carried easier, either in the hand or tied to the outside of a pack if you are really loading up. A leaking small container is less of a problem than a leaking lare container. I prefer recycled plastic beverage containers to fiddly things like hydration systems and collapsible bladders - they are just too likely to leak - the one exception seems to be Platypus bags, with which I have had no problems. It is very hard to buy a better water container than the one or two quart Gatorade bottles and they come prefilled. Incidentally I have found that dilute Gatorade works very effectively for me. In hot conditions, about half my liquid is dilute GA, and the rest is water.<br><br>If you are dealing with heat and water supply is a concern, you can travel much more efficiently by traveling at night (which may also present problems), or at least at dusk, or better yet, from daybreak until about 9 Am or so. Your water consumption will decline drastically if you avoid the hot daytime hours.<br><br>I guess I have a real thing about water - I got extremely thirsty a few times in twenty-five years in the Arizona outdoors - I am still rehydrating here on the California coast.<br>Water is one of those things you don't appreciate until you have been deprived a time or two - then you realize how easy it is to keep an adequate supply around.<br>