Survivalists and military personnel have long been familiar with the need to purify water from lakes, rivers and streams where safe water supplies are unavailable.  In addition to chemical pollutants, heavy metals and silt, portable water purification systems must be able to remove bacteria, such as E. coli, Salmonella (typhoid fever) and Vibrio cholera (cholera), protozoa such as Giardiasis and Cryptosporidium, parasitic worms such as liver flukes and schistosomiasis and viruses. 

For years, the process of boiling water to kill larger pathogens, using activated charcoal filtration systems to remove pollutants, and then adding chemical decontaminants such as chlorine and iodine to eliminate viruses has been the gold standard for obtaining potable water in the wild.  However, new technologies in the last twenty five years have created more user friendly alternatives for soldiers and nature enthusiasts alike.

Portable water purification devices, otherwise known as point-of-use treatment systems, employ a variety of technologies.  The Sport Berkey Portable Water Purifier uses a filter that removes contaminants by a surface phenomenon known as adsorption — the molecular attraction of substances to a media surface. Source water is forced through a filter that removes pathogens and toxic chemicals.

Aqua Sun produces battery and solar powered briefcase sized devices that can purify a gallon or more of water per minute using a combination of filtration and ultraviolet light disinfection.  This represents a significant improvement over the hand pumps that force contaminated water through filters that have been used by military personnel since the late 1980s. Hydro-Photon manufactures a portable, lightweight UV water purifier with the brand name SteriPEN that uses sunlight to induce DNA changes in disease-causing organisms. These DNA changes interfere with an organism’s ability to reproduce — rendering the pathogen harmless.

Though cutting edge, many of the newer technologies have their limitations.  For instance, devices like the SteriPEN are intended for use with clear water only, and devices that rely on filters lose their ability to extract contaminants over time and may even become pathogen reservoirs.  If you are venturing into areas where safe water is not available, consider the volume of water that you need to purify and the logistics of carrying a purifying device with you. There’s likely to be an optimal solution.

Photo by waterdotorg.