Hikers and campers who rely on surface water in wilderness areas need to disinfect the water before drinking it in order to avoid the risk of waterborne diseases. No matter how remote the area is and how clean the water may look, it could be carrying viruses, bacteria, protozoa or parasitic helminthes. Options for purifying drinking water without the addition of chemicals exist, but not all are equally effective.
Boiling water is the surest way to kill the disease-causing microorganisms in lake or river water, the U.S. Environmental Protection Agency confirms. You can avoid the possibility of nausea, diarrhea or stomach cramps from lake water by filtering it through a coffee filter or several layers of cheesecloth and then boiling it for one minute--or, if at a location one or more miles above sea level, for three minutes. Once the water has cooled, pour it back and forth from one clean container to another to aerate it and improve the taste, if you wish. Store boiled water in clean containers with covers.
Commercially-developed water filters for travelers are a common means for purifying lake water. With pore sizes between 0.1--0.4 micrometer, micro filters are an effective aid in removing bacteria and cysts from lake water, but may not be able to remove all viruses, the Centers for Disease Control and Prevention cautions. And viruses are a serious concern in lakes if the possibility of fecal contamination exists.
Solar Water Disinfection
Sunlight and clear plastic water bottles are all that is required for this simple and safe water treatment method. Researchers have confirmed that solar water disinfection--SODIS for short--is an efficient and effective method for obtaining drinking water, according to Eawag, the Swiss Federal Institute of Aquatic Sciences and Technology. To take advantage of solar power, simply fill PET bottles with water and place them in the sun for six hours--long enough for the sun's ultraviolet rays to kill the parasites, bacteria and viruses in water. This method, which is promoted for treating drinking water in developing countries, will work even if water and air temperatures are low, Eawag reports.
A squeeze of lemon or lime juice is a common addition to drinking water that may have developed because of the known antibacterial qualities of these juices. Citrus juice sometimes finds its way into commercial water treatment products for travelers. But insufficient data exists to justify the use of citrus as the sole water disinfectant, the Centers for Disease Control and Prevention state.