Securing a source of drinking water is necessary in any survival scenario, especially when traditional sources like streams or lakes are unavailable. Acquiring water requires recognizing that moisture is present in the environment in various forms, from the air to the ground. This process, sometimes described as “making water from nothing,” is the practical application of natural scientific principles like condensation and transpiration. By manipulating temperature, utilizing solar energy, and exploiting the biological functions of plants, an individual can reliably convert ambient moisture into potable water, ensuring short-term hydration until a permanent source can be located.
Harnessing Solar Energy for Condensation
The solar still is a low-tech method for producing pure water through distillation, relying on the sun’s energy for evaporation and condensation. This technique, often called a pit still, requires a digging tool, a collection container, clear plastic sheeting, and a small rock. Begin by digging a pit roughly three feet wide and two feet deep, centering the container at the bottom.
The principle relies on the greenhouse effect, where the sun heats the soil and organic material inside the pit, causing moisture to turn into vapor. This vapor rises until it contacts the cooler inner surface of the plastic sheet that covers the hole. The clear plastic must be stretched tightly over the pit and sealed around the edges with soil to trap the vapor.
A small rock is placed in the center of the plastic, positioned above the container. This weight creates a low point, directing the condensed water droplets to roll down and drip cleanly into the container below. The resulting water is distilled, leaving behind non-volatile contaminants like salts and heavy metals. To increase the yield, one can add fresh green plant cuttings or urine to the pit. The still must be left undisturbed for several hours, yielding a small but consistent supply over a full day.
Extracting Moisture from Vegetation
Water acquisition involves exploiting the natural biological process of transpiration in plants. Transpiration is the movement of water through a plant and its evaporation from aerial parts. To capture this moisture, a clear plastic bag must be secured tightly around a leafy, non-toxic branch receiving direct sunlight.
The sunlight heats the air inside the bag, causing the plant to release moisture vapor at an accelerated rate. This vapor then condenses on the inside surface of the plastic bag. Over the course of a day, the droplets accumulate and run down to the lowest point for collection.
Select a branch that is healthy and free of visible insects or animal droppings that could contaminate the water. Since the yield is relatively low, setting up multiple transpiration bags across several plants can increase the overall water supply.
Collecting Atmospheric Humidity
The atmosphere holds a significant amount of water vapor, which can be collected directly. The simplest technique involves harvesting dew, which forms when the air temperature drops to the dew point, causing vapor to condense on exposed surfaces overnight. Placing a clean, absorbent material, such as a large cloth or a tarp, flat on the ground before sunset can facilitate this collection.
In the early morning, before the sun evaporates the dew, the fabric can be wrung out into a container. This technique is labor-intensive and yields minimal amounts of water, making it suitable only for supplementary hydration.
Atmospheric Water Generators (AWG)
More advanced methods involve Atmospheric Water Generators (AWG) that actively manipulate the dew point. One common AWG technology uses a cooling-condensation cycle, similar to a dehumidifier, by drawing in ambient air and passing it over chilled coils. The air temperature drops below the dew point, causing the water vapor to condense into liquid droplets, which are then collected.
Another approach uses hygroscopic materials called desiccants, such as chemical salts or specialized gels, to absorb moisture from the air. Once saturated, the desiccant is heated, often using solar energy, to release the captured water vapor. This vapor is then cooled in a separate chamber, condensing into liquid water that can be purified and collected.
Ensuring Water Safety
Regardless of the collection method, collected water must be treated to ensure it is safe for consumption. Although condensation and distillation remove non-volatile contaminants, the water can still pick up microorganisms from collection surfaces, airborne pathogens, or residual plant toxins. Purification is necessary to eliminate biological hazards.
The most dependable purification method is boiling, which is effective against nearly all waterborne pathogens. Bringing the water to a rolling boil for one minute is sufficient to make it safe to drink. At elevations above 6,500 feet, boiling for three minutes is recommended due to the lower boiling temperature of water.
If boiling is not possible, chemical treatment offers an alternative using specialized tablets containing iodine or chlorine dioxide. These chemicals are added to the water and require a waiting period, usually 30 minutes, to neutralize pathogens. Filtration, using materials like cloth or charcoal, is a beneficial pre-treatment step for removing larger particulate matter before purification.