Viruses fly through the smallest pores, but they can be killed with water-treatment tablets after filtering. For instance, a filter with a 1-micron absolute pore size will trap giardia and cryptosporidium.
If hiking in the U.S., filtration is typically considered to be sufficient.Ī filter should remove the smallest infectious agents. And to reduce the bitter taste after treatment, aerate your water by pouring it back and forth between two canteens.įilters strain out microorganisms, but they don’t kill them. Tablets lose potency over time fresh ones work faster. Heat speeds chemical reactions, so you’ll shorten the purification time if you set your water in the sun while the tablets work. Much more time is needed for cold or cloudy water. Some negatives about using water-treatment tablets: They require at least 30 minutes to work if the water temperature is above 68 degrees. However, water-treatment tablets will not reliably kill cryptosporidium, which, fortunately, is uncommon in surface waters. Chlorine dioxide and sodium dichloroisocyanurate tablets are more effective against giardia than chlorine or iodine tabs. Water-treatment tablets are safer and easier to use. The Environmental Protection Agency recommends a one-minute rolling boil for elevations less than 6,600 feet and three minutes for higher elevations.Ĭhlorine bleach or iodine will kill most waterborne pathogens, but if you get the dosage wrong, they can be dangerous. The alternative is to go light and purify what you need.Įxamine the methods described here and determine the best option for the type of trip, the geographic area you will be visiting and the number of people in your group.īoiling water from an in-the-wild water source will kill almost everything, even parasites like giardia and cryptosporidium that can survive long exposure to iodine and chlorine. But at about 8 pounds per gallon, water can be a real drag if you have to carry it far. So unless you camp where safe drinking water is readily available, you’d best bring your own. THERE ARE FEW places in North America where you can safely drink water from a lake or stream.
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