Ask Buck

Freezing Point

Is there anything that can be added to water (that is safe) that will lower its freezing temperature?

Get access to everything we publish when you sign up for Outside+.

Question:

Is there anything that can be added to water (that is safe) that will lower its freezing temperature? This would be useful on a winter, overnight camping trip.

Answer:

There’s nothing practical and safe to add to water that will lower its freezing point very much. Salt water freezes at a lower temp that plain water, so a little salt will help, well, a little. Better to add powdered Gatorade or something similar, and the freezing point will drop a bit. Alcohol will lower the freezing point some too. But you use enough, say Jack Daniels, to lower the freezing point much and you’ve got a mind-altering substance. I use a few more practical ways in winter. 1) heat water up before bed, sleep with it in a bottle with a tight lid. 2) store water bottles upside down so ice forms on the bottom instead of freezing the lid on. 3) leave an inch or so of space in a water bottle during the day so the sloshing around slows the freezing process. 4) bury a bottle of water in a foot of snow and the snow insulates the water keeping it from freezing.