The ability to safely and efficiently purify drinking water in the backcountry is essential to your health and a trip’s success. Water is critical to performance and survival and demands attention when planning a trip. Understand the potential water contaminations in the area of your journey before you depart. Only then can you choose the best method and tool for dealing with the risk. There are three types of water contaminations to be concerned about in the backcountry — protozoa, bacteria, and viruses. They all revolve around contamination from both human and animal feces. We won’t knowingly drink from a water source near livestock, but may find ourselves on a horseback hunt with few other options. Proper latrine protocols and discipline should negate any contamination from human feces, but we can’t control all scenarios in the backcountry. We don’t know who or what’s been near our camps and potentially contaminating the water source we’re tapping. Even in very remote backcountry, we can’t be sure a herd of elk, domestic sheep, or humans haven’t recently contaminated the water source. The closer we are to population centers, trailheads, and roads, the higher the risk of contamination. It’s best to assume the water source is contaminated and treat it accordingly. Protozoa: Giardia and Cryptosporidium are the most common and extensive protozoa to be concerned about in backcountry water. These contaminants are also hardest to kill because of the durable, crab-like shell they form. This shell makes it difficult for chemicals to penetrate and destroy the protozoa. Filtration removes these harmful contaminants without the use of chemicals by filtering them out. You can simply filter the water and drink without concern. Chemical purification drops, however, require up to four hours of dwell time to entirely eradicate protozoa, depending on water temperature and turbidity. Bacteria: Bacterias include E-Coli, Cholera, and Salmonella. Bacterias are smaller than Protozoa and contracted from a water source contaminated with human and animal feces. E-Coli is the most prevalent in North America. Cholera and Salmonella are a more significant problem in developing countries. Viruses: Viruses, such as Hepatitis A, come from raw sewage and human feces. These are the tiniest form of water contaminants. Viruses are usually less common in backcountry water sources of developed countries in part to better sewage mitigation. Purification Methods: Purification, filtering, and boiling are three ways to decontaminate drinking water in the backcountry. One method may be more suitable than another, depending on the weather, type of hunt, and available water sources. Purifiers: Purifying water removes all three contaminants to an EPA-established standard. Purifiers come in tablets, drops, and UV devices like the Steripen. The biggest downside to these purifying methods is they don’t work well in water sources containing sediments like glacial silt, dirt, and algae. The above methods also don’t remove any particulate, making for chewy and crunchy drinking water. Tablets and drops are the lightest options for water purification in the backcountry. These chemical methods create a concentrated solution of Chlorine Dioxide that kills all contaminants, including viruses. This method is very similar to those used in many municipal public works. Tablets are lightweight and take up little room. There’s no reason not to carry a few for contingencies. I have a pack of tabs in my optics harness and a few more in my survival kit. The downside with tablets and drops is the requirement to wait 4 hours to kill all contaminants. This dwell time is not convenient in most situations and tempts you to drink much sooner, risking getting sick. UV water treatment has become popular for backcountry use. Tools like the Steri-pen have changed how people think about water purification. UV treatment allows a safe and convenient way to purify water without chemicals or waiting 4 hours to be fully effective. UV treatment doesn’t remove particulates in the water and is not very effective in water sources that contain them. This is a consideration depending on the environment you’re traveling. High alpine trips are good candidates for a Steri-pen where the water is generally clear, cold, and flowing. A 90-second treatment with a UV device and a liter of water is safe and ready to drink. Filtration: Filters only remove protozoa and bacteria but are usually suitable for backcountry water sources of developed countries. Filters come in many forms, from pumps and straws to gravity-fed systems. Pumps move water through a filter by the manual labor of the user. Depending on the filter, ergonomics of the pump handle, and water source, this task can become a workout. One issue with pumps is finding a good pool of water to access. Small seeps and drips from glaciers and snowfields are problematic when using pumps because there’s not enough room to get the intake filter submerged. Gravity systems utilize gravity to drain water through the filter into a clean bottle or bladder. These systems can produce large volumes of clean water with minimal effort. Ingenuity allows small water sources to be accessed, funneling water into the first bladder. In the high country, tapping into seeps, drips, and puddles provides access to precious water and could be the only source available. Ceramic filters are best for large volumes of water. One downside is that they require cleaning and maintenance for long service life. I’ve also had ceramic filters freeze and crack in cold weather without my awareness. These cracks can subject the user to contaminated water without notice. Hollow fiber filters don’t crack in cold weather, are less expensive, and provide less resistance when in use. Hollow fiber filters clog more often than ceramic and require more frequent back-flushing depending on how dirty the water source. This is usually a minor inconvenience after you get your back flush protocol dialed. No matter the filter, it’s good practice to use an inline pre-filter before the primary. A pre-filter becomes mandatory with water containing lots of particulates like mud or glacial silt. The pre-filter catches larger particles, keeping the primary filter functioning longer and reduces the number of times it needs to be cleaned. Boiling: Boiling kills all protozoa, bacteria, and viruses but requires the use of fuel. You also may need to allow the water to cool before drinking, depending on how you’re using it. Hot water on a hot day is not conducive to drinking. Hot water in cold weather, however, could be what you desire. To kill all contaminants, bring questionable water to a rolling boil for at least one minute at altitudes up to 6562’/ 2000m or three minutes for altitudes above 2000 meters. I don’t use boiling as a primary purification method unless it’s winter. If snow covers the ground, then I’ll melt snow for drinking water. I’m not generally concerned with snow being contaminated, especially if it recently fell. I don’t typically boil the water after I’ve melted snow unless I’m using the water for a dehydrated meal or hot drink. This approach is usually safe and saves stove fuel. Conclusion Water is your life-blood on a wilderness trip. The sources and methods of procuring and treating it should be a priority when planning a trip. Lack of water can reduce your physical and mental abilities in challenging terrain when you need all your faculties. Lack of water will affect your trip quicker than a lack of food. Understand the area and plan your water treatment methods accordingly. Some ways are better suited to particular environments and trip types. Experiment with different treatment methods and become comfortable using them all for best success. Gear References These links take you to some of the gear I use and rely on in the mountains. This is not a definitive list but a good place to start. Ultimately, testing and training allow us to dial in a system that works for each of our unique requirements. Purification MSR: www.msrgear.com Katadyn: www.katadyn.com Aquamira: www.aquamira.com Filtration MSR: www.msrgear.com Katadyn: www.katadyn.com Platypus: www.platy.com Boiling MSR: www.msrgear.com Primus: www.primus.us