You can live without food for weeks, but you’ll die of thirst in three days. You need water to survive. But you’re surrounded by snow, right? So water isn't a concern. Except that it is. Eat too much snow to gain water, and you’ll lower your body temperature to the point of hypothermia, and eventually death. You need to collect water, store it, and maintain reliable sources of good-quality water. Sometimes, out of desperation, you might take a chance on a bad source of water, and end up poisoned.
Water is a constant concern.