Backcountry Water Purification

By Brady MillerMarch 5, 20132 Comments

LAST UPDATED: May 1st, 2015

While backpack hunting in the mountains, one of the main concerns I always have is keeping track of how much water I have available and when I will be able to fill up next. Water is everything while bowhunting in the backcountry…if you’re not adequately hydrated then you will not hunt hard, you will not think clearly, your recovery time at night will be slower, and it is just not safe. Proper water purification is something I feel very strong about, mostly due to past experiences. Drinking straight from a stream or high mountain spring, no matter how pure the source looks, is a bad idea. All water may contain disease causing microscopic organisms such as Cryptosporidium and Giardia. So why risk it?

I am fortunate enough to work in the backcountry all spring, summer, and fall, as well as bowhunting the backcountry. I spend upwards of 150 days in the field each year, most of which are weeklong backpacking trips. Proper water filtration is one of my highest concerns, and I have had the opportunity to test out a lot of different purification methods over the years. I cannot stress how important it is to carry some sort of purification method to ensure the water is safe.

Personal Experience
In 2011 while working in the backcountry, I let a friend use my filter and when he returned he informed me that it was hard to pump, due to him pumping in a swampy area frequented by moose. A week later I used it one time in the backcountry, noticed it was clogged, and therefore for the rest of my six day trip I used purification drops. When I got back from that trip I had nine days off to bowhunt elk. After getting all my gear packed and making the long drive to the trailhead, I started to get sick when I loaded my pack on and tried to hike. I thought it would just pass so I told my friend to start hiking and that I’d join him shortly. After an hour or so he noticed I wasn’t catching up to him. When he came back, he found me on the ground at the trailhead. I had gotten sick extremely fast and was vomiting. My friend drove all night in order to get us home.


Using some sort of water filtration system (like the author shows here) is one method for purifying water before drinking it in the backcountry.

To make a long story short, the next few days were very miserable. At the time I thought I just had food poisoning, so right when I started feeling better I drove back out to my elk hunting spot, only to find myself even sicker once I climbed into the mountains. Elk were bugling, and I tried to hunt but didn’t have the strength to chase them. So I lay in pain for two days in my little one man tent until I had enough strength to get off the mountain and drive home. I was then diagnosed with Giardia and prescribed medicine. It was two weeks later that I finally was cured. I lost a total of 17 pounds during that time because I couldn’t get food to stay in my system. Giardia is a nasty thing to have, especially during the elk rut!!

Methods Of Protection

Water filters come in many shapes and forms. Compact backpacking style filters typically simulate a bike tire pump, with a canister that holds the filter, a pumping handle, and a hose to fill up your water bladder pouch or bottle. Another option would be a gravity style filter if you might be camping near a water source the entire duration of your hunt. Filters are very fast at pumping water and are easy to use. Just remember to keep the hose out of silt or debris to keep the filter clean.


Chemicals are an alternative to filtration systems. Shown here are chlorine dioxide drops that will be added to water.

A word of caution…not all filtration devices are 100% effective at removing harmful organisms. Most filters will protect against the common harmful microscopic organisms like Giardia and Cryptosporidium. Filters do not remove viruses, and not all of them treat against bacteria.

Boiling is very effective at removing all pathogens and the water should be brought to a rolling boil for three to five minutes or more depending on how high in elevation you are. You may be able to get by with a shorter boil…but once again, why risk it? During the spring and late fall when the snow is flying I will boil snow so I don’t have to drop to lower elevations to reach flowing water. I only do this if I have extra fuel for my stove, as this method tends to burn up fuel reserves quickly.

Chemicals can be used to treat water if you follow the directions carefully. A few of the common forms are iodine tablets and chlorine dioxide drops or tablets. They are lightweight, don’t take up much room in your pack, and are freeze-thaw stable. All three are effective against bacteria and viruses. Iodine is not very effective at preventing Giardia or Cryptosporidium, while chlorine dioxide is. There are many factors that affect the use of chemicals, such as water temperature, water turbidity, and water pH.


Iodine tablets are another method for making water safe to drink and the tablets weigh next to nothing and take up very little space in your backpack.

The downfall to chemicals is the wait time to take their full affects before you can drink the water- most people are not willing to wait that long until they can drink water which significantly lowers the effectiveness. Iodine tends to give the water an unpleasant taste for some people. I personally don’t mind it; friends of mine will cover the taste up with either a powdered sports drink or vitamin mix.

Ultraviolet light
I briefly want to touch on some new technology for purifying water. Ultraviolet (UV) light pens seem to be a topic of a lot of discussion lately. The water is exposed to UV light for a period of time, which will kill off viruses, bacteria, and protozoa. The downfall to this design is the UV light is not very effective in murky water, and the device needs to use batteries. I am always a little hesitant about carrying more battery powered devices into the backcountry. I have not personally tested this method, but I can see the benefits of it.

Filter Straws
Filtration straws seem perfect for emergencies if your main water filter becomes inoperable. They allow you to drink directly from the water source by pulling water into your mouth with a small tube and filter. The downfall to this system is that you cannot place the filtered water into a container for later consumption, as it is a drink now system. The only option you have is bottling the water up and then drinking from it through your filter straw at a later time. This system will remove Giardia and Cryptosporidium.

Side Notes
Keep in mind that you should avoid gathering water at places that wildlife frequent. Look for signs of their use, and gather your water away from the area that they are frequenting. You just never know if they are urinating or defecating at their water source. Extra caution should be given in areas where livestock are present.


No matter how safe a water source may look NEVER drink from it without first purifying the water. You never know what is going into the water source upstream from your location.

A great technique that I have started using is a “filter and treat” method. Utilizing this process, I simply filter water and then treat it with a chemical to further remove harmful organisms before drinking. This process may take a little longer, but I usually drink a bunch of my remaining water before I start filtering; this way after I “filter and treat”, I can start hiking and let the chemical run its course before consuming water. Last but not least, if you are in serious danger of dehydration, drink the water! It is much easier to treat for diseases later when you return from your trip than to risk losing your life.

Closing Message
In closing, there are plenty of water purification options out there, so there is no need to risk drinking straight from the water source. Options are endless right now as far as filters go…there are even more designs that I didn’t cover that might suit your needs. So I suggest doing some research to find that perfect option for you. I chose to review the methods that I feel will get the job done in the backcountry under strenuous hunting conditions. Enjoy your time in the backcountry because there is no better thrill than hunting deep in the mountains!

Brady Miller
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