It’s fun to catch snowflakes on your tongue, but you might wonder whether it’s safe to eat a lot of snow, use it in snow ice cream recipes, or melt it for drinking water. The bottom line is that it’s safe to eat clean snow, but even the whitest snow still has some contaminants, plus you shouldn’t eat snow to rehydrate. Here is a look at how to collect snow that’s safe to eat, which snow to avoid, what contaminants occur in snow, and why you need to melt snow rather than eat it for hydration.
It’s generally safe to eat clean snow. For drinking water, melt the snow. Ideally, boil and filter it before use.
Snow You Shouldn’t Eat
You should avoid snow that carries a high risk of contamination. Snow absorbs chemicals from its surroundings, plus there are many organisms that live in snow. Any color besides pristine white is a red flag. It isn’t just the urine-colored snow you need to worry about. Snow can be colored because of algae, pollution, dust, pollen, or other sources, some capable of making you sick. Similarly, avoid the very first snow that falls because it picks up the most particles from the air. You shouldn’t eat:
- Snow near a major highway
- Plowed snow
- Discolored snow
- The bottom layer of snow that touches the ground
- Snow from trees or other plants
- The first flakes from a snowstorm
Safe Snow Collection
Hikers, hunters, and mountaineers all over the world routinely use snow as their primary water supply with no issues. You can collect clean snow, even if you live in a city.
- If the snow is falling, simply collect it fresh from the sky in a large, clean pot or bowl. Eat it right away, melt it for water, or store it in your freezer.
- If the snow has already fallen, scrape away the exposed surface and collect snow beneath it. Don’t go down so far that you get snow in contact with plants or soil.
Contaminants in Snow
A snowflake is a water crystal. Crystallization purifies water, so each flake is very pure, except its very center, which might be a bit of dust or particle of pollen. However, snow falling from clouds to the ground picks up particles in the air. Once snow is on the ground, debris settles onto it and organisms grow in it.
The nature of the contaminants in snow varies according to where it falls. Snow near a city might have more residue from automobile emissions, while snow in a field might have more dust. Snow near a road has vehicle emissions, plus possibly road salt or other surface treatments. Not everything picked up by snow is unhealthy, but it can contain some nasty chemicals. Snow contaminants include heavy metals, polycyclic aromatic compounds, pollen, soil, dust, pesticides, soot, and other pollutants. Once the snow falls, some of the volatile compounds escape back into the air. Others react with each other to make additional toxic or carcinogenic compounds.
Chemicals aren’t the only concern. While bacteria and viruses aren’t a big concern, algae, fungi, and cyanobacteria colonize snow. Some of these organisms are toxic. A fair number of creatures live in it, too, including beetles, spiders, springtails, wasps, and scorpionflies. Some people view the critters as a natural protein boost, but most are grossed out.
Despite the chemical cocktail, clean snow tends to be safer than most public drinking water. Most of the time, contaminants are present in trace amounts. So, eat snow, but be careful where and how you collect it.
Eating Snow and Dehydration
Pure snow is solid water, but if you’re thinking of eating it for hydration, think again. Water has a high specific heat, so your body expends considerable energy melting it from a solid into a liquid. Burning energy requires water from the stores already inside your body. You use more water than you get, so eating snow dehydrates you.
Of course, it’s perfectly fine to use snow as a water source as long as you melt it into a liquid and then drink it. Ideally, you should boil and filter it because melting snow doesn’t kill any microorganisms living in it.
- Garbarino, J.R.; Snyder-Conn, E.; et al. (2002). “Contaminants in arctic snow collected over northwest Alaska sea ice”. Water, Air, & Soil Pollution. USGS. doi:10.1023/A:1015808008298
- Hall, Ellen L.; Dietrich, Andrea M. (2000). “A Brief History of Drinking Water.” Washington: American Water Works Association. Product No. OPF-0051634.
- Jones, H. G. (2001). Snow Ecology: An Interdisciplinary Examination of Snow-Covered Ecosystems. Cambridge University Press. ISBN 978-0-521-58483-8.
- Nazarenko, Yevgen; Fournier, Sébastien; et al. (2017). “Role of snow in the fate of gaseous and particulate exhaust pollutants from gasoline-powered vehicles”. Environmental Pollution. 223: 665 doi:10.1016/j.envpol.2017.01.082