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My vehicle has broken down in the middle of a desert, I have some tools but I am out of water. I have the ability to make a fire.

I know that drinking antifreeze is fatal, but I am wondering if I can distill drinkable water from the antifreeze or any of the other fluids in the car.

I am also aware that automotive batteries are usually refilled with distilled water.

Automotive Fluids.

  • Water mixed with antifreeze (radiator)
  • Battery fluid
  • Windshield washer fluid
  • Brake fluid
  • Power steering fluid
  • Motor oil
  • Transmission fluid (automatic)
  • Gear oil (Manual transmission, differentials)
  • Fuel (gas or diesel)

Short term survival is the goal, living long enough to die of cancer in 10 years because there was a carcinogen in something, is not a bad option.

We have an existing post Finding water in the dry wilderness but it does not address the several gallons of fluids that might be available in your automobile. This question is specific to automotive fluids.

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    The desert is not critterless or plantless and the air has some moisture which will condense and might be trapped at night. I suggest you ask about options to get water in the desert instead of going straight to the fluids in the car – ab2 Feb 11 '18 at 16:13
  • @ab2 we already have that question Finding water in the dry wilderness – James Jenkins Feb 11 '18 at 16:44
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    Ozzi outback preparation involves flushing antifreeze out of the radiator and using only clean water in the washer bottle for this very reason. – user5330 Feb 12 '18 at 3:47
  • Possible duplicate of Finding water in the dry wilderness – Liam Feb 15 '18 at 12:59
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    Though I get your point, ultimately there are better ways to get water than using the fluids in your car. – Liam Feb 15 '18 at 13:00
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There are three fluids in your car that contain water: the battery electrolyte, the washer fluid, and the coolant. Everything else is hydrocarbon-based, and in a properly-functioning car, contains no water.

  • In the battery, the electrolyte is a mix of sulfuric acid and distilled water. A modern sealed battery keeps the amount of electrolyte to a minimum, so it's not a good source of water even if you could neutralize the acid.
  • Washer fluid is typically a mix of water, an alcohol (usually methanol), and detergent; in colder climates, it often has ethylene glycol mixed in to lower the freezing point.
  • Coolant is roughly a 50/50 mix of water and antifreeze, typically ethylene glycol.

Ethylene glycol has a boiling point of 197°C, well above that of water. If you're desperate, your best bet is to set up a solar still to extract the water from the antifreeze. The difference in boiling points means that your still will be producing reasonably pure water.

Distilling the washer fluid has the problem that methanol boils at a lower temperature than water. The initial output of the still will be a poisonous methanol/water mix, and there's no good way to tell when the methanol level has dropped far enough to be safe.

A long-shot option is to make your water. Hydrocarbons produce carbon dioxide and water vapor when burned; you could attempt to disassemble your car's exhaust system and use it as a condenser to capture some of that water vapor. Of course, in the long run, you're likely to wind up with heavy-metal poisoning, or unburned hydrocarbons giving you cancer.

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    Sorry, I have to down-vote this for not making it very very explicit that what OP asked about was a dangerously bad idea. Even IF you could somehow distill all the dangerous stuff out of some of these fluids (pretty safe to assume that in a survival situation you can't) it will hardly be worth the effort to screw around with your car and improvised stills for a day to extract maybe 1 litre of drinkable something... – fgysin Feb 15 '18 at 12:11
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    I don't feel downvoting is needed. Words like "desperate" seems sufficient here. On one hand, it could be dangerous, doing dangerous desperate things. On the other hand, if you're in a survival situation, everything should be on the table. If my choice is between being desperate and dying, I'll pick desperate, and figure the rest out later. – Cort Ammon Feb 15 '18 at 19:06
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None of these fluids can be made "safe" for consumption.

Most of these liquids are oil based with these exceptionn:

  • battery fluid: is a strong acid, which is diluted with water

  • washer fluid: water with some detergent, which might be the least harmful combination, but will potientially interfere with your body chemistry

  • water with antifreeze - dont drink antifreeze, 'nuff said

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    If you live up North, washer fluid also has antifreeze in it. – ShemSeger Feb 11 '18 at 19:41
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    The washer fluid is also likely to contain quite a lot of methanol. Alcohols (ethanol/methanol/isopropanol) are added both for reasons of cleaning and to stop it freezing. Methanol is highly toxic. Ethanol isn't used alone is ln cleaning products - it's denatured by adding methanol. Isopropanol isn't as bad but you don't want to drink it either. – Chris H Feb 11 '18 at 20:14
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    I think you really need to explain why none of these fluids can be made safe. Is it not possible to make them safe in a fully equipped chemistry lab or simply with the equipment and supplies in a car? Even oil may have the necessary components (hydrogen and oxygen) to make clean water. – StrongBad Feb 12 '18 at 15:58
  • @StrongBad That wasn't the question though... I really agree here in a survival situation as described by OP you are way way way better of not trying to drink any of these. – fgysin Feb 15 '18 at 12:03

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