What is the safest and most effective additive to keep drinking water from freezing?

If you need a water supply that will not freeze without additives, dig a hole in the ground. In the hole place a hard sided cooler . The top of the cooler should be no less than 1 foot below ground level. Drape a small tarp or other heavy material that will not degrade. The tarp will rest over the cooler and overlap the sides of the hole. Fill over the top with clean backfill. Place a wooden rod on 2 opposing sides of the tarp that come out of the hole and staple the tarp around the rod on each end to be used as handles. Whenever you need access place your foot on one handled side and pull the other side up, dirt and all. Get your drink, and put the tarp and dirt back in place. This works and is a common sense approach to having good old drinking water that will not freeze and has worked for me in winter camps where temps dove to 15 F at night. Hope you find this fairly simple approach useful.

posted almost 5 years ago

CC BY-SA 4.0

Simple Man‭

11 reputation 0 1 1 0

Propylene glycol is allowed in alcoholic beverages up to 5%, and this would get you to about 29°F.

You could probably throw in a little sugar, salt and good old ethanol to kick it down further. Really, nearly any solute will push down the freezing point. Maybe some salty chicken bullion, plus alcohol just to keep it from rotting. This is starting to sound like a bad idea.

posted almost 9 years ago

CC BY-SA 3.0

Pepi‭

161 reputation 0 34 16 0

There are two natural options; none of them is quite pleasant.

Alcohol

Per Wikipedia, 8.5 vol% of ethanol make the freezing point drop to -3C (26.6F) (more values at at Wikipedia, also a diagram is available below).

Most of the ethanol will be evaporized during cooking, so it's not that much an issue; also 14 vol% is only 6.8 wt%, so the added weight is 6.8%, which sounds like a lot, but still it's 1/15 only. The good thing is that you can get cheap and quite strong alcohol almost anywhere around the world. Of course, this has some issues, such as where to get spare alcohol for a longer journey; also, some alcohol will be always left in the solution, no matter how hard you try, which is not good at winter.

Note that you can get a 90% alcohol at special shops, but it can get quite expensive because of the excise tax. Don't buy technical alcohol, it's denaturated, i.e. very disguisting and possibly not really safe to drink.

Salts

Note that you can't really do much with salts. The most efficient salt is NaF (sodium fluoride). However, it is poisonous, lethal dose is around 8g/100kg weight. We can compute that even a huge amount such as 34 grams of NaF in 1 litre of water reduce the freezing point to -3C. However, that's 3.4 wt%, which is freakingly lot.

For NaCl (kitchen salt), the amount to get to -3C is 47 grams, so almost 5%. Since the relationship is linear, any reasonable amount of salt has close to zero effect on the freezing point.

Conclusions

Do not do this. Find other methods how to supply yourself drinking water in extreme conditions.

posted almost 9 years ago

CC BY-SA 3.0

yo'‭

21 reputation 0 1 2 0

It's pretty easy to keep your water from freezing without adding anything to it, actually. If you keep it under your shell, your body heat will keep it from freezing. If you bury it under a foot or so of snow, it will stay liquid overnight (although you may get a little ice around the edges). If you boil it and put your hot water bottle in your sleeping bag, it won't freeze and you'll have toasty-warm feet. Insulated bottle jackets and vacuum-sealed thermoses are also awesome.

And if you need water in larger amounts, just melt snow or ice (haul a block with you, if you won't have snow), or bring an ice axe to get through the ice covering a nearby body of water. (A small hole is all you need; the water pressure will fill the "bowl" you chipped away to get down to the bottom of the ice.)

There may be chemicals that will get the job done, but it seems to me you will almost always be better off with good old water.

posted almost 9 years ago

CC BY-SA 3.0

samglover‭

81 reputation 0 10 8 0

Electrolytes

You can use an electrolyte solution in your water. Many do this for obvious other reasons but it will reduce the freezing point in the water.

I'm sure you've seen the various powders at health food or supplement stores.

I wish I had a good citation but sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), chloride (Cl−), hydrogen phosphate (HPO42−), and hydrogen carbonate (HCO3−) all reduce the freezing point of water a bit and if your working hard are essential to body chemistry.

Good for you and reduces the freezing point.

posted almost 9 years ago

CC BY-SA 3.0

Citizen‭

16 reputation 6 4 2 0