This post was last updated on July 1st, 2021 at 08:35 am
Water Purifying Guide
By Kiel Bowman
Clean water is one of the strongest necessities in the backcountry and during survival situations, and you must take some steps to ensure it. There are a lot of ways to clean your water these days: mechanical filters, chemical purification, UV purification, and your bare bones boiling. There also ways to enhance some of these methods, to varying end results, such as using a carbon component to enhance flavor after chemical purification. If you are stranded in the backcountry you could also check out, the procuring clean water for survival page.
So which one is best for you? Let’s take a look.
First, you need to know the nitty gritty of what it is that needs to be cleaned out of water to make it safe. There are three groups of concerns: protozoa, bacteria, and viruses. Common parasites such as Giardia and Cryptosporidium, can easily ruin your hiking and backpacking trip. We’ll leave the more scientific explanations of each to the scientists, but the bottom line is that the presence of any of these can turn your trip into a nightmare if they succeed in attacking your body after ingestion by causing diarrhea, vomiting, and other symptoms. Not all water cleaning methods are made equal; mechanical filters do not filter out viruses, for instance. Some methods change the taste of water, sometimes for the better and sometimes for the worse.
1. Mechanical Filters
There are two types of mechanical filters available: pump or gravity. Pump filters work by filling water into one reservoir, and then using a mechanical system activated by a pump to force it through a filter into another reservoir. Aside from boiling, this is the oldest method of cleaning water, and its tried-and-true results are attested to by its enduring popularity. Gravity filters work with essentially the same concepts; two bags connected by a tube with a filter in it, one bag containing the dirty water and the other bag being the receptacle for the clean water. However, instead of having to pump it, you simply hold or hang the dirty bag higher than the clean bag, and gravity does the work for you, pulling it through the filter. It does take some time, so few people will resort to holding the dirty bag aloft. Most instead suspend it in a bush or a tree. It doesn’t take that long, however, and a flow rate of one liter per minute is not uncommon in current models. Both filters separate protozoa and bacteria from the water, as well as silt and other detritus. The result is clean tasting water that will keep you healthy, as long as there are no viruses to worry about. Viruses can only be removed by purifying water. Water filters don’t purify water, they filter it. The name difference is actually an important detail. For bang for the buck, we tend to side with gravity filters. They’re less hassle and effort, and are eminently portable, collapsing to tiny proportions.
2. Chemical Purification
There are a wide variety of chemical purification methods available, the most common of which is iodine. Iodine is frequently used in emergency areas, such as for refugees from earthquakes or war, for quickly purifying water for many people to drink. However, iodine and other chemical purification tablets greatly affect the taste of the water. Although there are additional systems available to enhance the flavor after purification treatment, this results in just requiring more gear. You also might still need some kind of filter to remove silt, dead bugs, or decaying plant matter. If that’s a concern in the location you’re drawing water from, you can use charcoal and other natural materials in a bushcraft water filter tripod to enhance the flavor and texture. The bottom line is that these tablets are so small and inexpensive, that it makes perfect sense to keep some in your backpack at all times.
3. UV Purification
UV purification is a relatively new technology that has grown increasing popular, with products like the Steri PEN. These tools are convenient, as they’re usually very small, and appealing due to the low level of fuss involved with their use. However, it is of my opinion that they are not yet true contenders for being a viable method of widespread water purification. For optimal use, you are recommended to find water that is already as clean as possible, and you have to make sure to follow the guidelines in how to use it to ensure that the UV light properly breaks down the DNA of all pathogens within the water. Naturally, UV light also doesn’t address silt and other unwanted matter in the water, meaning that if that’s a concern in your water source, again, you will still need some sort of filtration device afterwards. We believe that there’s a lot of potential in this technology going forward, however, as of now, it is still not an optimal choice for water cleaning. If you are confident that the water sources you will be drawing from are free of unwanted matter, then this might be a great choice due to its portability. Otherwise, you might want to stick with a filter.
Boiling is still always an option, as it does in fact kill protozoa, bacteria, and viruses. However, it takes time, fuel, and a clean boiling vessel. Most hikers will be carrying something that they can boil water in, however, considering the small size and weight of today’s modern water filtration systems, boiling water is just not as fun (or easy). All that said, If there is ever any doubt about the quality of the water after filtration, just boil it.
In case you didn’t notice, we recommend a gravity filter more than other systems. Given that our site is geared towards hiking in high elevation areas in North America, viruses are an almost unheard of problem, so purifying water completely is rarely a necessity on the trail. Instead, keeping out bacteria and protozoa is the main concern, followed by making sure that the water is actually nice to drink. A gravity filter will accomplish these tasks for you, without taking up much space in your pack, and at a low cost. What more can you ask for? There is, however, one caveat to be considered with any filter device, which is doubly important for our favorite high elevation backpacking areas. Freezing will render a filter useless, and so you must take care to keep it dry. Also, you should take care to frequently clean the filter, for reasons that should be quite clear. This takes minimal effort however, and so we still endorse the gravity filter.