It takes a large volume of snow to produce a small amount of liquid water (the ratio is roughly 10:1).

In a survival scenario, snow should be boiled before drinking to ensure it is clear of contaminants.

The mod Snow is water [B41.74 Legacy] (or its variations) fixes a logical gap in the base game: by default, rain barrels do not collect water during winter when it snows.

It is essential for "winter storm" or "Cryogenic Winter" playthroughs where natural liquid water is scarce.

Outside of gaming, "Snow is water in a barrel" refers to the practical survival technique of collecting snow to melt for fresh water.