I was just reading the Wikipedia article on Body Water:
http://en.wikipedia.org/wiki/Body_water
It mentions “the total amount of water in a man of average weight (70 kilograms) is approximately 40 liters”.
Wow!
That could get you out of trouble if let’s say, you’re stuck in the middle of the Sahara. What do I need to get the water out of that sucker? I reckon a straw won’t do the trick. Will fire get me halfway there?
No, I don’t need an urgent answer.
Some sort of solar still? Chop the cadaver into small pieces (you can probably drink the fluid in the eyeballs straight away, to keep you going while you work) Put the pieces in a pit (or a large container), cover with polythene and put a weight in the middle of the polythene to make a dip. Position a cup in the middle of the pit or container to catch the water dripping off the inside of the polythene.
A man’s flesh is his own, but his water belongs to the tribe.
The trick wouldn’t be getting the water out.
Hell, just seal the corpse in an airtight container and I suspect after a month or two it’d be a skeleton with a nice layer of corpse water on top.
The trick would be getting pure water that was drinkable. As a macabre experiment I’d put the corpse through a high shear mixer, centrifuge the slurry, filter, then treat the supernatant with iodine to kill any living micro.
Ugly, messy, unethical (if one presupposes most religions’ rules for how to treat the dead). Also disgusting. But if you were living on Arrakis, maybe that practice would be standard.
Bear Grylls could rig up something.
Suck as much moisture as possible from the blood and muscle and then skin the corpse to use as a sun-shade.
Shout to it, then strike it with a stick. He’s as dead as a stone. Worked for Moses.
You’ll need some power tools, a box of straws, and a really big thirst.
A wood chipper and a still.
This seems to me that it would work quite well, although it would be a macabre process to set up. You also may want to have more than one still, to further purify the water.
Muad’dib! Muad’dib!
Why? You can extract potable water from poisonous vegetation and piss and poop by means of a solar still. However, you will need to defend your still from predators looking to snack on the corpse. I don’t know how long it would take to dehydrate a corpse in the desert sun, nor do I know how much would be unextractable. This is the Straight Dope, however, and I expect someone here knows the answer.
Mmmm, corpse water.
I wouldn’t place too much reliance on a solar still, wiki says, and I’ve heard that although it’s always talked about in survival school, those that actually tried it would agree
‘Knowing how to put together a solar still is often billed as a useful survival skill and could provide an important means of potable water in the event of a wilderness emergency. Nevertheless, under typical conditions makeshift solar stills rarely produce enough water for long-term survival, and the sweat expended in building one can easily exceed its daily output.’
Whether or not that is true doesn’t impact whether the water is safe to drink after one distillation.
Also, solar stills are for emergencies, not a permanent means of getting water.
Rob
I’m not commenting on the sterility of the water or a stills long term usefulness, but rather it’s practicality in a desert survival situation.
As are corpses. 
Corpse water. Delicious but deadly.