5 November 2008
Clean, Safe Water in the Backcountry
Posted by admin under: cooking; gear; safety; survival .
Humans are 70% water, so finding clean, safe drinking water to stay hydrated is a high priority in any outdoor activity. This is especially true when your survival and health depends on your own resources. Pretend you have been hiking all day, and your bottled water just ran out. You found what you think is a fresh spring and the water looks clean. Just drink straight from the babbling water, right? No way. Simply drinking from any fresh water source can and most likely will cause serious health problems.
So, what do you do next? Well, there are three main methods of purifying water to drinking condition: boiling, treatment with chemicals, and filtration.
The tried and true method for attaining clean, safe drinking water is boiling in a pan of some sort. The CDC (Center for Disease Control) recommends keeping the water at a strong rolling boil for one minute. Some sources recommend as much as five minutes depending on the water’s origin; dirtier water requires more time. A strong, rolling boil will kill all pathogens in minutes. Even resilient bacteria in developing countries succumb with longer boiling times. Filtering out water through a piece of cloth like a bandanna before boiling will remove most organic material like dirt, moss, and algae. Unfortunately, boiling water requires an adequate amount of fuel, a hot enough fire to sustain high temperatures, and extra equipment. Boiling the water also adds a smoky flavor to the water. Adding a pinch of salt to the water or pouring it from one container to another multiple times improves the flavor. Another method for purification, though less reliable than boiling, is chemical treatment.
There are two main chemicals used for purifying water taken from a stream, pond, or other water source: chlorine and iodine. Chemical treatment is an attractive alternative to boiling because it doesn’t require much equipment or a heat source. Iodine tablets are available at pharmacies and sporting goods stores, and are effective against most pathogens. Unfortunately, iodine does not kill cryptosporidium, bacteria that cause a diarrheal disease. Iodine also creates a heavy chemical taste and the amount needed varies greatly depending on the quality of the water. The CDC only recommends iodine for short-term use, as long term exposure causes health complications. Chlorine, on the other hand, is effective for long-term use. Chlorine eliminates most pathogens, but cryptosporidium can survive in chlorinated swimming pools for days. Compared to iodine, chlorine has a less consistent germicidal use. Effectiveness depends on the PH level of the water, the organic content of the water, and the water temperature. One disadvantage to chlorine tablets is that it can break down over long-term storage or when exposed to higher temperatures. Always check the manufacturers label on iodine or chlorine tablets and follow the instructions for safety. Realistically, chemical treatment is most effective in conjunction with water filtration.
When used in with chemical treatment, water filtration is nearly as effective and consistent as boiling. Filtering the water through a piece of cloth first will help prevent the filter pores from clogging. Filters don’t require a fire or fuel and filtered water has a clean taste, but need replacement periodically. Cryptosporidium bacteria slip through most conventional filters, so look for filters designed to handle it. The CDC recommends looking for the filter labels to say one of the following for complete effectiveness against cryptosporidium: “reverse osmosis,” “absolute pore size of less than or equal to one micron,” or “tested and certified by NSE international (formerly the National Sanitation Foundation) standard 53 or NSF standard 58 for cyst removal.” Due to the risk of manufacturer’s flaws, filters are less reliable than boiling water, so treat filtered water chemically if possible to be safe. Always treat the water with chemicals after filtering, as chlorine can damage filter membranes.
Never underestimate the importance of clean, safe drinking water. Step one is finding a source of water, but you must always take precautions even if you are verging on dehydration. Boiling will always work, and chemical treatment after filtration works nearly as well. Before setting out to camp, backpack, bike, or do anything outside for an extended amount of time, know where your clean water will come from. You will have more fun and will feel better throughout your trip if you stay hydrated.
One Comment so far...
Chuck Says:
6 November 2008 at 11:21 am.
I work for the American Chemistry Council and have done a few Outward Bound trips, and I can definitely recommend chlorine. It’s actually used in most U.S. drinking water supply systems and has been used for 100 years because it’s so effective at killing harmful bacteria.
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