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Backcountry Water Purification

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Treating Your Drinking Water On The Trail

Before backpacking the Appalachian Trail, I'd done a lot of hiking, but the majority of those trips had lasted a day or two at most. So I'd been able to carry all the drinking water I needed, straight from tap to Nalgene bottle, and never had to obtain extra supply from backcountry sources. Therefore, I never had to treat that water, either.

Thinking back, though, I was foolish not to have carried some method of purifying water, just in case, even on those shorter hikes.

Of course, when it comes right down to it, better to drink when you have to and worry about treating the after-effects AFTER. Dying of dehydration is much worse than having the "goon clutch," as my dad used to put it. But, better yet, go prepared and avoid the bathroom blues altogether.

On my thru-hike, with stretches of up to seven days between town stops, carrying water treatment products was no longer an option but a necessity. There were hikers who chose to play Russian roulette, but, like most, I preferred to purify rather than puke (etc.).

Along the way, I tried a number of methods and products, which I'll share with you here, along with some I haven't used. There's a lot of information out there about treating water and a myriad of products to choose from, so I'd encourage you to look into the area you'll be going, to find out which waterborne nasties are most prevalent and the types of sources you'll likely encounter. This information may make a difference in the method -- or, better yet, methodS -- you choose to bring along.

Why Purify?

You've been hiking for hours. It's hot and dry and, boy, are you thirsty. And, lo and behold, the most beautiful, clear, babbling brook presents itself. So why not simply drop to your knees, cup your hands and drink?

Well, if bloating, diarrhea, headache, vomiting, flatulence, cramping, and a fever rolled into one miserable ailment sounds like fun to you, go for it. Take your chances and perhaps you'll be just fine. You'll find out for sure in about seven to twenty-one days.

But if you want to play it safe, assume that any water from untested sources is not safe to drink until treated.

There are two basic types of contaminated water. Biologically contaminated water contains microorganisms -- bacteria or viruses -- that can cause gastrointestinal infections. Toxic water sources contain chemicals, such as mine tailings, pesticide runoff, gasoline and motor oil. Boiling, filtering, or chemically treating water can remove microorganisms but not chemical toxins.

If you think a water source is chemically contaminated due to its color or smell, find another source if at all possible. You'll need additional treatment methods to render such water potable.

Of the biological contaminants, Giardia, a microscopic parasitic cyst, is the most common and widespread. All surface water should be suspect, including clear-looking mountain streams. This intestinal bug is spread through oral-fecal transmission (um, that's basically poop to mouth) and is carried by humans and animals. Animals certainly aren't particular about where they relieve themselves and, in many cases, neither are humans, who often enjoy the view (and perhaps the background noise) of a lovely babbling brook while assuming the position over a cathole.

Cryptosporidium is the second most common microscopic critter in our backcountry water sources, with the same mode of transmission and lovely symptoms as Giardia.

The above image is in the public domain.

The EPA says....

At least 90% of the world's fresh water is contaminated.

Water Purification Options Covered Here

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Boiling
Water Filters
Iodine
SteriPen
Bleach
Chlorine
Filtration Water Bottles
Grapefruit Seed Extract

Boiling

Back to the water purification basics

Pro: Boiling is the most reliable water treatment method, effectively destroying contaminants.

Con: This method requires significant fuel, time and effort.

Of course, if you're going to boil, you'll also need fire starter, a pot and, unless a natural wood fire is your preference, a backpacking stove. Water temperatures above 160 degrees F will destroy all the bad bugs within a half hour. Make that 185 degrees, and you can cut the time to just a few minutes. Fact is, once you get the water to a rolling boil -- 212 degrees F at sea level -- it's okay to drink. Even at high altitudes where the boiling point is below 212 F, the water is still hot enough to have destroyed any unwelcome organisms. As a general rule, if you bring water to a full boil for one minute, it's safe.

Of course, then you have to wait till it cools down, unless you're having a hot beverage.

Note: If you have to use water contaminated with algae or particles, it's advisable to pre-filter with a layer or two of cloth. Bandannas are handy for straining (not to mention a number of other uses). But try to avoid pond scum, which may contain toxins that can kill animals and sicken people.

The above image is in the public domain.

Water Filters

Purify with a pump

Pro: Removes all organisms except the smallest viruses and yields instant potable water.

Con: Filtering requires pumping, adds weight to your pack, and is somewhat costly.

There are two basic types of filters -- membrane filters and depth filters.

Membrane filters contain thin sheets with specifically and evenly-sized pores that prevent objects larger than the pores from passing through. These filters are fairly easy to clean but do clog more quickly than depth filters. One example is the PUR-Hiker.

Depth filters contain thick, porous material such as carbon or ceramic to trap particles as water flows through. Activated carbon filters remove a range of organic chemicals and heavy metals, but the filters can be cracked if handled roughly, making them useless because untreated water can seep through the crack. These filters can be partially cleaned by back-washing. Two examples of depth filters are the MSR WaterWorks II and the Katadyn.

There is a difference between a water filter and a water purifier. Filters don't eliminate viruses, but there are purifiers, such as the PUR Scout, that pass the water through a filter and an iodine compound that kills any smaller organisms that sneak past the filter. Such purifiers zap all microorganisms larger than 0.004 microns, but they shouldn't be used by those allergic to iodine.

As a rule, filter the clearest water you can find. Dirty water or water with large suspended particles will clog up your filter more quickly. As with boiling or virtually any treatment method, strain either through a pre-filter on the pump or a piece of cloth. If that's not an option for some reason and you have to filter dirty water, let it stand overnight so the particles can settle out.

Note: If the intake hose on a water filter has been in contact with untreated water, consider the hose contaminated and keep it in a separate baggie. Once the hose is dry, it's no longer a concern.

The depth filter I used on my A.T. thru-hike was the....

MSR Miniworks

MSR MiniWorks EX Microfilter

Amazon Price: $84.99 (as of 02/14/2012)

The MiniWorks EX has a ceramic element that can be cleaned repeatedly, with no tools required for disassembly. This lightweight and compact filter can pump one liter of water per minute. The kit includes the Miniworks EX, a stuff sack, a hose float, scrub pad and instructions.

Usually ships in 24 hours

Another Recommended Water Filter

A filter that's adjustable for different conditions

Katadyn Vario Water Filter

List Price: $89.95

This filter combines a ceramic disc that lengthens the life of the filter when using with dirty water and a pleated glass fiber element which makes it easy to operate.

Usually ships in 24 hours

More Water Filtration Products For The Backcountry

Your Feedback On Water Filters

Do you use a water filter? Why or why not? Tell us which kind/s you've used and what you did or not like.

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Yes, I prefer a water filter.

e-xplorations says:

Water filter are effective devices for purifying drinking water. But I would still suggest boiling water for a period of time. Its the primitive yet the most reliable water treatment I know.

Posted August 26, 2011

TravelingRae says:

My group used the pump filters on the Chilkoot Trail. It was great! The water tasted good and I only pumped 1L at a time, so it wasn't exhausting. The device isn't that heavy either.

Posted August 19, 2011

RenaissanceWoman2010 says:

I use the MSR MiniWorks.

Posted April 19, 2011

jasonklass says:

I always use a filter. For years, I used an MSR Miniworks but now I use a gravity filer I made myself using a Aquamira Fronteir Pro. I hate pumping water.

Posted October 18, 2010

Bex says:

These filter overviews are great! I also recommend them on my blog http://www.backpackingwithbex.com - great!

Posted May 19, 2010

No, I don't use water filters, or I have but don't like them.

BoyScoutPopcorn says:

We used the Katydyn pumps on High Knoll and Dolly Sods, and they worked fine. We used iodine at Northern Tier, and I like that process better. Faster results, less time and work, and less gear to haul.

Posted November 22, 2011

GrandMemories says:

No, I keep my hikes short enough that a Camelback is sufficient.

Posted May 17, 2011

view all 12 comments

Iodine

Tastes like sucking on a kiddie pool

At least, that's what I thought of the taste when I used it, specifically Polar Pure iodine in solution.

Pro: Iodine is an effective disinfectant for Giardia when heating or filtration are not convenient or desired.

Con: It makes the water taste funky and requires a certain amount of time, depending on the water temperature -- at least 10 minutes in warm weather and as much as eight hours in cold.

When it comes to the unpleasant taste, though, that can pretty much be eliminated with pills made for that purpose or even with a drink mix, like Tang or Gatorade powder. Adding about 50 milligrams of straight vitamin C also has the same effect. But I was told to add the vitamin C or drink mix after the treatment time, so the iodine doesn't adhere to the flavor crystals. Whether that's a fact or not, I'm not sure, but it sounded logical and wasn't an issue, so I stuck to it.

Many people consider iodine to be an emergency water treatment method, based on the fact that iodine overload can cause problems if one has any kind of thyroid deficiency; however, those with normal thyroid function can tolerate high amounts of iodine. I used Polar Pure for about 4 out of my six months on the A.T. and never noticed any ill effects.

Note: If you so have any thyroid issue, consult a physician before using iodine for more than emergency purification.

Polar Pure

This was my back-up water purification method on the Appalachian Trail

Polar Pure Water Disinfectant With Iodine Crystals

Amazon Price: (as of 02/14/2012)

Polar Pure uses crystallized iodine to destroy water-borne pathogens including giardia cysts and viruses that pass through filters. Just add water to the Polar Pure bottle and then, using the dosage chart on the bottle, add the proper amount to your drinking water container. This product is effective to use as long as you can see iodine crystals at the bottom of the Polar Pure bottle.

More Iodine Water Treatment Products

Lightweight and convenient for backpackers

Your Feedback On Iodine For Purifying Water

Have you used an iodine product? Tell us why or why not and what you think.

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Yes, I've used iodine to purify water.

BoyScoutPopcorn says:

Used it at Northern Tier. Like I said before, it worked fine for us without any issues.

Posted November 22, 2011

Jane says:

I've used Potable Aqua on a couple of backpacking trips, and as long as I couldn't see the water (that lovely yellow) I barely noticed any taste. I didn't know about the (potential) dangers of iodine overload, so it's good to know about that, now. I love that these tablets are so small and light. While in camp, I always had two water bottles, so while one was purifying (half an hour according to the instructions on the bottle) I could drink from the other.

Posted January 17, 2010

MysticTurtle says:

I always carry Polar Pure as a backup. I used it a few weeks on the AT when my filter got clogged. The taste didn't bother me...it was certainly better tasting than the water I filtered from that nearly dry swamp.

Posted March 12, 2009

Ramkitten says:

I used Polar Pure for four out of the six months I was on the A.T. The off taste didn't bother me, especially because I'd add drink mix (like Tang or Gatorade) after letting the iodine in solution work for 20 minutes or so. It was easier for me than stopping to take off my pack and filter, although I definitely had to strain through a bandana at times to take out the floaties. I still carry Polar Pure, at least as a backup.

Posted March 11, 2009

No, I don't use iodine.