I have just quickly read Touching The Void by Joe Simpson…a survival story about two guys coming off a mountain.
Anyway, in the story it quotes on page 65: “The gas was all used up in the breakfast routine, and there would be no more water until we got down to the lakes below the moraines.” They had been using heat to warm snow/ice for drinking water.
This isnt the first time i have heard/read of this before…the need for cold weather adventurists to melt snow to get a water supply.
If they are thirsty, why can’t they just eat snow?
I can’t go into details (primarily because I’m ignorant of the details), but the bottom line is that you don’t want to eat snow because you run the risk of lowering your core body temperature too much.
It’s not so much a ‘don’t eat any snow or it’ll kill you’ as it is a need for quite a bit of water and eating snow doesn’t give you much, so the risk of cooling yourself by eating a lot of snow is there.
Another concern is that snow is not purified. There are a number of bacteria and other things that live in snow that aren’t good for you. Relatively minor if it’s a matter of getting down in a day, but major concern if getting sick will leave you on the mountain.
Extremely cold snow has a risk of damaging body tissue as well.
cite? Just curious. I’ve eaten snow all my life with no i-with no i-with no i-LL effects.
My winter camping instructer had us just melt the snow, not boil it. Just make sure where you are getting the snow is clean, and don’t dig deeper than you can see lest there be a carcus or other unpleasent suprise buried deep. We’d skim the top inch of the snow into the pot and then boil.
I do a lot of ski mountaineering, including considerable camping.
Snow isnt very dense, and it is hard to eat enough of it to slake ones thirst. When you have run out of water and are thirsty eating snow is a pretty common practice, but it usually only helps to take the edge off, it is difficult to eat enough of it. You can only eat a bit at a time because your throat gets to cold and hurts, and yes it cools you off pretty quickly.
Temperature regulation is an important task in winter activities, and it takes little time to go from being uncomfortably warm to being chilled after stopping for a few minutes. It depends on the temperature as well, at -5 C its not going to be such a big deal, at - 20 C you cool off very quickly.
If you are working hard, are not already to dehydrated, its not to cold and you have the time to stop every few minutes to grab and eat a handful of snow you can probably get rehydrated. Understand though when you are working hard you have to breath hard and when you are chewing snow you are not breathing. Stoping every five minutes to eat some snow for a minute slows you down a LOT. Its usually better to grab the odd handfull and boogie back to camp or an open creek.
Usually when you do run out of water it is pretty late in the day, you are tired and you are dehydrated and under those conditions it is much harder to regulate your temperature. With a broken leg, in the dark after hours and hours of exertion sitting and eating snow until you are rehydrated is a recipe for hypothermia. I am sure those guys were grabbing snow constantly but generally remained dehydrated until they got back to camp or to a water source.
I don’t know the exact species of bacteria that thrive in snow, but I do know most aren’t killed by freezing. Best cite I can find is this paper. There’s also snow algae ( a common red species in the Sierra Nevada gives the name ‘watermelon snow’). Not all algae is bad for you, of course, but some is. Without even thinking to check, I found this via Google.
Of course you will probably be fine eating unfiltered snow melt, especially in places where the snow is fresh every year. Indeed most people would be fine drinking unfiltered water all the time while camping, but a fair number would get sick. For those that are climbing in very unforgiving conditions, it’s a much more dangerous risk.