What isn't mentioned here is that some desert area mountains, lets use Utah for an example. There are water sources there, but also most of the water is not consumable as the minerals in it will kill you.
One has to decide to hydrate with what water source they have before venturing 5 miles. The temperature plays a big factor and what type of clothing you are wearing, if you can actually make it 5 miles, then you have to decide, do you leave all your equipment, backpack, etc?.
Many would be able to do so, but in 120+ degree temperatures walking 1 mile will exhaust some, make you sweat extremely more than normal and possiblities of heat stroke, or heat exhaustion if not careful, if you just have a T-shirt on firmly fit pants and no hat the possiblities of hazard for one is predictable!
If wearing loose clothing, loose long sleeve shirt, and a hat. Your body will remain somewhat cooler by retaining your sweat on your body not alllowing it to evaporate quickly as opposed to what I mentioned above.
I been out in the desert, with hardly any mountains and if I had the choice. My first option would be dig down in moist sand and get water, filter it the best I could, and drink as much I could stand before going the 5 miles. At least I would plenish my body a bit before going out on a hike.
Let's throw in the equasion. Lets say you have all your prospecting gear, or a backpack, because if one went out in the desert they didn't just hike there with the clothes on their backs. People take things with them.
But, the REAL ANSWER to this question that NO ONE has mentioned, NOT EVEN SPART! You got there by some means right? Well, the answer is, YOUR DROVE YOURSELF THERE now get in YOUR MODE OF TRANSPORTATION and DRIVE to the mountains or NEAREST TOWN!!!!!!
Now with that said, lets say your vehicle broke down? Now there would be something in your vehicle anyone could possibly use to trap water, as mentioned above, a plastic bag of some sort, etc. BUT; Here is something many don't think of;
Fact is some people will use just plain water instead of washer fluid for your windshield washer bottle for your vehicle, (I use plain water and for this reason), you have at least 1 gallon of drinkable water. Many people to do not know of this or realize it being a water source no matter where you go you may not have drinkable water if you get stranded, but don't think of the windshield washer bottle as a drinkable water source. I make sure my washer bottle is full of clean water before making any trip and I don't us it to clean my windshield!
Now if you have no means of removing the water out of the bottle, but have a plastic empty bottle or two in your veihicle and no tools to remove the bottle and no straw to transfer the water, How would you get the water out of the washer bottle to another container? I know the answer, I want to see what anyone elses imagination would be. There is a clue in my posting if one thinks about it! Too easy!