Eating snow

Yes, snow is clean enough that you don't need to treat it after melting, as long as it hasn't been contaminated after falling.  Since it may be hard to say if the snow on the ground hasn't been touched since falling it is safer to treat chemically or with boiling, but newly fallen snow is safe.  Snow is not very dense, so it takes a LOT of snow to make enough water for a family for a day.  When melting snow, put a little water in the pot with it; otherwise you can scorch it.  By the way, eating a lot of unmelted snow can lower your body temperature dangerously, so if you're outside, far from shelter/heat, don't eat large amounts of snow.  Smaller amounts should be OK.