Glaciers, immense bodies of ice formed over centuries, often evoke images of purity and untouched wilderness. This perception leads many to assume that the meltwater flowing from these ancient ice formations is inherently safe to drink. While visually appealing and clear, untreated glacier water carries significant, hidden risks that are not immediately apparent to the eye. Drinking directly from a glacial source without proper treatment can lead to various health issues.
The Allure and Reality of Glacier Water
The visual clarity and perceived ancient origin of glacier water often lead people to believe it is pure and safe to drink. However, this overlooks the complex journey water takes as it melts and flows through the environment.
Despite its inviting appearance, glacier meltwater is not sterile or automatically safe for consumption. As water flows over and through rock, soil, and even the glacier itself, it can pick up various impurities. Even in remote areas, meltwater can accumulate contaminants from wildlife, atmospheric deposition, or geological interactions, challenging the notion of inherent purity.
Hidden Dangers and Contaminants
Untreated glacier water can harbor various contaminants. Biological agents, such as bacteria (E. coli), viruses, and parasites (Giardia lamblia, Cryptosporidium parvum), pose a significant concern. These waterborne pathogens can cause gastrointestinal illnesses with symptoms like diarrhea, nausea, and cramping. They can be introduced by animal waste, human activity, or emerge from melting ice.
Chemical pollutants can also infiltrate glacier water, originating from both distant and local sources. Persistent organic pollutants (POPs), including industrial chemicals and pesticides like DDT and polychlorinated biphenyls (PCBs), can be transported through the atmosphere over long distances and become trapped in glacial ice. As glaciers melt, these chemicals can be released into the meltwater, potentially contaminating downstream environments. Heavy metals like mercury, lead, and arsenic can also be present, released as glaciers grind down underlying rock or from atmospheric deposition.
Physical contaminants, though less immediately harmful, can also affect water quality. Sediment, dust, and fine rock particles, sometimes referred to as glacial flour, are common in meltwater and can make the water cloudy. While generally not a health risk, these particles can clog purification filters and affect the water’s taste. Microplastics, a growing global concern, can also be present in glacial environments and are released into the water as ice melts.
Making Glacier Water Safe to Drink
Several effective methods exist to make glacier water potable. Boiling is the most reliable way to eliminate biological contaminants, including bacteria, viruses, and parasites. Water should reach a rolling boil for at least one minute, or three minutes at elevations above 6,500 feet. This heat effectively destroys harmful microorganisms.
Water filtration is another method, particularly useful for removing larger biological contaminants and physical particles. Filters designed for backcountry use typically have a pore size of 0.5 microns or less to effectively remove bacteria and protozoa like Giardia and Cryptosporidium. Some advanced filters can remove particles as small as 0.02 microns, while others, like those with a 0.22 micron pore size, are considered “sterilizing grade” for bacteria removal. It is important to note that most filters alone do not remove viruses, which are significantly smaller than bacteria.
Chemical treatments, using tablets or drops containing iodine or chlorine dioxide, can also purify water. Chlorine dioxide is effective against bacteria, viruses, and giardia cysts, and some formulations meet EPA guidelines for microbiological water purifiers. Iodine can also be used, but it may leave an unpleasant taste and is not always effective against Cryptosporidium. Chemical treatments typically require a waiting period, often 30 minutes, to allow the disinfectant to work.
Combining methods often provides the highest level of safety. Filtering water first to remove sediment and larger particles can make chemical treatments or boiling more effective, as turbid water can reduce their efficacy. A combination approach ensures comprehensive removal or inactivation of a wider range of potential contaminants.
Responsible Interaction with Glacial Environments
Interacting with glacial environments requires a commitment to responsible stewardship, particularly concerning water sources. Adhering to “Leave No Trace” principles helps minimize human impact on these fragile ecosystems. This includes proper waste disposal, such as packing out all trash and burying human waste at least 200 feet away from water sources.
Protecting water quality also involves avoiding the use of soaps or detergents directly in streams or lakes. Instead, carry water at least 200 feet away from waterways for washing, and scatter any strained dishwater broadly. These practices prevent introducing contaminants that disrupt the delicate balance of glacial ecosystems.