In the United States, the average person uses about 75 gallons per day of freshwater. Most of this water is pre-treated in facilities and comes out of the tap clean and ready for drinking, a fact many take for granted. If you are camping and hiking you won’t always have access to this source of healthy, potable water. Unfortunately, many water sources in the wilderness include microorganisms, bacteria, viruses and contaminants.
Boiling water is the most effective way to kill all disease-causing microorganisms, such as E. coli, Cryptosporidium and Giardia lamblia, which are present in lakes and rivers. Depending on your elevation level, you should boil water for different lengths or time. Water temperatures above 160° F kill all pathogens within 30 minutes and above 185° F within a few minutes. According to the Centers for Disease Control and Prevention, water should be brought to a rolling boil for one minute. At altitudes greater than 6,562 feet you should boil water for three minutes.
If boiling water is not an option, you can chemically treat your water with halogens such as iodine and chlorine. There are many products on the market that include iodine or chlorine in liquid and tablet forms specifically for water purification. The effectiveness of these products depend on the temperature, pH level and clarity of the water. Be sure to check the expiration dates on your water purification products. If they have expired, they may not be as effective. If the water is cloudy it will require more chemicals to treat. If the water contains large particles, strain it through a cloth before you treat the water. The water should sit at least 30 minutes after the treatment tablet has dissolved. Water that has a temperature below 40° F should sit for an hour.
People with thyroid problems, on lithum, women over 50 and pregnant women should consult their doctors prior to using iodine for purification. Also, some people who are allergic to shellfish are also allergic to iodine. If you fall into these categories use chlorine-based products or a non-iodine-based filter.
There are many water filtration systems on the market that reduce microorganisms in water. However, the effectiveness of the filter depends on its pore size. It is very important to know what pore size (measured in microns) your water filter is and what it will filter out. For example, a water filter with a pore size of 5 microns or larger will filter out protozoa such as Giardia, while a smaller filter of .2-.5 microns will filter out bacteria such as Cholera, E. coli, and Salmonella, and a filter with a size of .004 microns will filter out viruses such as Hepititis A.
The advantages of using a water filter is that water is available for drinking immediately without an unpleasant taste. Disadvantages are that the filters often get clogged and they may not filter out everything that could make a person ill. If in doubt, it is best to combine water filtration with chemical treatment or ultraviolet treatment.
Ultraviolet light purification works by inactivating microbes by destroying their DNA, which prevents them from reproducing. The water being purified must be relatively clear (have a low turbidity) for the water to become potable, thus water may need to be filtered before ultraviolet radiation can be used. This method of water purification requires batteries for the ultraviolet light, so be sure you have extras on hand if you are planning an extended trip.