I can speak to this from direct experience: unless you're downwind of Chernobyl or equivalent, snowmelt is safe to drink. I've been doing it for 20 years, and I'm still kicking.

Note that ice is entirely different: it is only as pure as the stream or lake it came from. That usually means "boil it."

I've been drinking snowmelt since, well, forever. Two water bottles, packed with the cleanest snow I can find, and tucked inside pockets while I snowshoe up a hill, yield drinking water.

If you can heat water, and make tea or hot chocolate, that's a bonus. I always carry a steel cup of some sort. Actually, boiling water is a huge bonus ... that's the difference between 'surviving' and 'living outdoors in style and comfort.' Old-time trappers used to bile-the kittle for a mug-up as standard operating procedure, every few hours.

Another consideration: in cold conditions, you don't feel thirsty. But you need to be well hydrated to "burn" food, to keep the metabolic fires burning. I've sometimes forced myself to drink, and then felt better. Dehydration kills in cold as well as heat.

Like OBG, I'm more scared of the cooties in a T-shirt than the snow.

Not that snowmelt is sterile; it isn't. Lots of bacteria hitchhike on the dust particles that coalesce raindrops etc. etc. etc. Nowhere on Earth is really sterile, even the upper atmosphere. But the cooties that cause us problems are generally in short supply in rain/snow.

Anyway, I'm rambling. Bottom line: Drink The Snowmelt!