The practice of collecting “moss water”—water gathered by squeezing moisture directly from moss—is an unreliable and unsafe method for obtaining drinking water. Any water acquired from a natural, untreated source must be considered contaminated. This water is not potable without proper treatment, and relying on it can lead to severe gastrointestinal illness. Dangers stem from biological and chemical contaminants that are easily trapped and concentrated within the plant’s structure, necessitating a multi-step purification process before consumption.
Immediate Biological and Chemical Hazards
The primary danger in consuming untreated moss water is the presence of pathogenic microorganisms. These waterborne threats include bacteria such as Escherichia coli (E. coli), which can cause severe diarrhea and vomiting. Protozoa, like Giardia lamblia and Cryptosporidium parvum, are also common in surface water. These resilient parasites can lead to debilitating, long-lasting intestinal infections.
Viruses, although smaller, pose another significant risk, often originating from human or animal waste runoff. Since moss is typically found near the ground, the water it holds is surface water, making it a collection point for contaminants from animal droppings, decaying matter, and environmental debris. Stagnant or slow-moving water sources, which feed the moss, are breeding grounds for these organisms.
Beyond biological threats, the water can contain chemical hazards that are invisible. Surface water, especially near human activity, can carry agricultural runoff like pesticides and herbicides. Heavy metals, such as lead, arsenic, and mercury, may also be present in regions with a history of mining or industrial activity. These chemical contaminants are not eliminated by simple field filtration and require specialized processes.
Why Moss Does Not Purify Water
The belief that moss acts as a natural purifier is a dangerous misconception. Mosses, as non-vascular plants (bryophytes), absorb water and nutrients directly through their leaves, lacking the complex internal filtering systems of vascular plants. This structure causes them to function like a sponge, absorbing water up to 20 to 30 times their dry weight.
This high absorption capacity means mosses collect and hold whatever enters their environment, including pollutants from the air and rainfall. They are highly effective at absorbing dust particles and heavy metals, which is why scientists use them as bio-indicators to monitor environmental pollution. Instead of disinfecting water, the moss acts as a collection mat, potentially concentrating dissolved chemicals and fine particulate matter.
While moss can physically trap larger sediment and debris, this coarse filtration does nothing to eliminate microscopic pathogens. The pore spaces within the moss structure are far too large to block out bacteria, viruses, or protozoan cysts. Therefore, water squeezed from a moss clump may look clear due to the removal of large particles, but it remains biologically and chemically unsafe.
Necessary Steps for Water Purification
Making any questionable water source, including moss water, safe for drinking requires two distinct steps: initial filtration and subsequent purification. This dual approach addresses both large contaminants and microscopic pathogens. Removing particulate matter first is necessary because turbid or cloudy water reduces the effectiveness of purification methods like chemical treatment.
Initial Filtration
The first action involves pre-filtering the collected water to remove visible sediment, silt, and large organic debris. This is accomplished by straining the water through a tightly woven cloth, such as a bandana or shirt material. Removing these particles prevents clogging specialized water filters and allows chemical purification agents to work more effectively. This step is purely for clarity and does not eliminate any disease-causing organisms.
Boiling (Gold Standard)
Boiling is the most reliable method for sterilizing water and is considered the gold standard for killing biological contaminants. Heating the water to a rolling boil for at least one full minute is sufficient to neutralize all common pathogens, including bacteria, viruses, and protozoa. At elevations above 6,500 feet, the required duration should be increased to three minutes to compensate for the lower boiling temperature. This heat-based process is effective against even resilient cysts, such as Cryptosporidium.
Modern Filtration
Advanced portable water filters and purifiers are widely available and offer a highly effective alternative to boiling. These devices typically use micro-filtration media with pore sizes small enough to physically block bacteria and protozoa, often down to 0.1 or 0.2 microns. Filters using pump or squeeze mechanisms are effective field tools, but they require regular maintenance to prevent clogging from sediment. However, most standard field filters do not reliably remove viruses, which are much smaller, meaning a secondary purification step like boiling or chemical treatment is often necessary.
Chemical Treatment
When boiling is not possible, chemical purification tablets or liquids offer a viable disinfection alternative. The most common active ingredients are iodine or chlorine dioxide. Chlorine dioxide is preferred because it is effective against Cryptosporidium when given sufficient contact time, whereas iodine is not. Proper usage requires following the manufacturer’s directions exactly, including the specific dosage and the required wait time, which can range from 30 minutes to several hours, especially if the water is cold. Chemical treatment is a reliable way to kill most pathogens, but it can leave a noticeable aftertaste and is less effective if the water is murky.