This is an idea I’ve been kicking around in my head for some time now. Come wintertime, keeping your water from freezing in the backcountry is vital. I eschew hydration bladders altogether once the snow flies, as the “tricks” to keep it unfrozen (blowing air in the tube, get an insulated hose, etc.) are all too unreliable. I’ve occasionally seen it suggested to add a little vodka to your water to lower the freezing point, but always wondered just how effective that relatively small amount of alcohol would be. I finally got tired of simply wondering, did some research, and threw everything in to a spreadsheet.
I imagine that will be an unintelligible mess for most, though there is an order to the chaos. In addition to ethanol, I looked in to the effects of sugar and salt. If there are any chemists out there who see I’ve made a grave error somewhere, please let me know so I can correct it.
From my calculations, it appears that there’s no way to substantially lower the freezing point of water without making it undrinkable while mountaineering. A half teaspoon of table salt, 1.5 fluid oz of 40 proof vodka, and two tablespoons of table sugar will get you 200 Calories, more than double the sodium in a bottle of Gatorade, and a freezing point depressed by an entire 1.6 degrees F. I’m going to do some testing and will follow up on this; at this point it doesn’t appear to be very beneficial from an “antifreeze” standpoint, though for a mountaineering drink it could be quite effective. The small amount of alcohol may increase circulation to fingers and toes, the salt provides needed electrolytes, and the sugar provides fuel.