>>829609You need 1.5 gallons per day. This includes water you get from food.
Source. Been going to Burning Man for 6 years, and I do a lot of camping in the middle of fucking nowhere.
You can get by with less than a gallon if you're in a humid environment, and you're not exerting yourself, but if you are hiking, or in an elevated desert, you need that 1+ gallon.
And remember, always piss clear.