It’s the same as rainwater, except it isn’t polluted by gases from the atmosphere since it is in solid form. It is H2O in the most pure form you’ll probably find in nature. Upon touching the ground it will of course be contaminated, but a forest floor normally won’t give problems.
If you want to carry around such an amount of water and have time to collect it (it takes a lot of snow indeed) during the walk you could give it a try.