Modern conveniences have made desert camping easy. Four-wheeled or all-wheel drive vehicles are common and provide reliable access to remote areas. There are excellent maps. Comfortable camping equipment makes sleeping under the stars a wonderful experience. You can carry more water than if you were backpacking (remember, water weighs eight pounds per gallon). And we cook and eat magnificently (Freeze-dried stuff? Never. We prepare gourmet food on one or two burners.)
The limit is always water. When we run out of it, we must leave or move and find a place to refill our water bottles.
This year, there were three of us. We had a total of around seven gallons of water, plus perhaps another gallon of drinks (fruit juice, beer, wine) in a cooler with our food, plus whatever water was in the food itself.
The water itself had to serve for cooking, drinking, and cleaning. And it lasted three nights and parts of four days for three people – nearly three full days measured in hours.
We used it for drinking: to fill our water bottles that accompanied us on our hikes through washes and canyons and across a long valley to an old mining site and desert oasis. Perhaps four gallons over the time we were out.
We used it for washing and rinsing dishes and pots after cooking. Each major meal (three dinners and three cooked breakfasts; lunches were sandwiches, fruit, cookies) could be cleaned up with around a quart of water – say another two gallons. [As an example of how opportunistic desert life is when a source of moisture appears, here is a photo of what showed up within a minute or two of cutting open an orange.]