Backcountry Water Purification Techniques and Products
Treating Your Drinking Water On The Trail
Before backpacking the Appalachian Trail (<--my journal), 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 with their untreated drinking water, but, like most, I preferred to purify rather than puke (etc.).
Along the way, I tried a number of purification methods, 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.
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 contamination. Biologically contaminated water contains microorganisms -- bacteria or viruses -- that can cause gastrointestinal infections. Toxic 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 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 sources, with the same mode of transmission and lovely symptoms as Giardia.
The EPA says....
At least 90% of the world's fresh water is contaminated.
Back to 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. Temperatures above 160 degrees Fahrenheit 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 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 degrees, 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.
If you need a fast, lightweight backpacking stove for boiling and cooking, this is the one I recommend and use....
I've used this compact backpacking stove on many treks, bringing water to a rapid boil in as little as a minute. (Boiling times are somewhat affected by altitude.) Larger compatible pots are available for boiling more at one time.
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.
TYPES OF FILTERS
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 Katadyn Hiker Pro Microfilter.
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. An example of a depth filter is the . (More information on this and other water filters below.) MSR MiniWorks EX Microfilter
FILTERS VS PURIFIERS
There is a difference between a filter and a purifier. Filters don't eliminate viruses, but there are purifiers, such as the MSR Sweetwater Purifier System, 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 (which is really small!), but they shouldn't be used by those who are allergic to iodine.
BACKCOUNTRY FILTERING BASICS
As a rule, filter the clearest water you can find. Dirty water or water with large suspended particles will clog 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 Reliable MSR Miniworks - Speaking from experience....
This isn't the fastest filter out there, but that's because it's doing its job well.
I used this filter on my Appalachian Trail thru-hike.
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.
More Quality Products For The Backcountry
Including this first model that's used by the military because it's so tough and reliable....
This one is pricey for a good reason. It's super durable, dependable and lasts a long time, which is why it's popular with the military.
This microfilter features a silver-impregnated ceramic element that's effective against bacteria and protozoan under all sorts of conditions. Unlike disposable filters, the ceramic element can be cleaned several times in the field. And the element filters all microorganisms larger than 0.2 microns.
In fact, this filter can produce up to 100 times more water than standard filters.
Other features include a measuring gauge that indicates when you should change the filtering element, a cushioned base that makes it easy to pump on all surfaces, a prefilter, and a carrying bag.
I'm currently using this model and really like it. It's never clogged and pumps fast. The cartridge has to be replaced when it gets really dirty, because you can't clean it the way you can clean a ceramic cartridge, but it does have a removable filter protector that extends cartridge life in challenging conditions.
The replacement Katadyn Hiker Pro Replacement Cartridge has a capacity of up to 200 gallons, depending on how dirty the water is. (How much sedimentation is in it.)
A Backcountry Base Camp Filter
This is a great filter for your campsite. You just fill it with unpurified water and hang it up. No pumping required. This filter produces up to 2.5 gallons in 15 minutes. It uses a field cleanable Hiker PRO cartridge and can filter 200 or more gallons (more when using the Filter Protector).
Your Feedback On Filters - Please share your comments and help others decide
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.
Yes, I prefer a water filter.
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 thyroid problems; 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.
Iodine Treatment Products - Lightweight and convenient for backpackers
This was my back-up purification method on the Appalachian Trail.
If you really want to get rid of the yellowy color and the "funky" taste of iodine-treated water, use this product instead. You drop in an iodine tablet and then one of the PA plus tabs to eliminate the funkiness.
Your Feedback On Iodine
Have you used an iodine product? Tell us why or why not and what you think.
Yes, I've used iodine to purify water.
The UV Way of Purifying H2O
PRO: Convenient, quick and lightweight
CON: Murky water must be pre-filtered.
This is a fairly new process for treating water in the backcountry, with design innovations that have minimized the size and weight of these devices. The SteriPen Adventurer weighs just 3.6 ounces including the batteries and will purify 1/2 a liter (or 16oz) in less than a minute, or 1 liter (32oz) in 90 seconds.
The SteriPen destroys viruses, bacteria and protozoa, but it's not as effective in murky, sediment-filled water. So if you'll be treating water that isn't clear, it's best to filter through the SteriPen Prefilter, which you can purchase separately, or a piece of fabric like a bandana or even a coffee filter before using the SteriPen.
I've used the Steripn on several backcountry trips and have found it reliable, convenient and fast. It's especially nice when it's really buggy -- mosquitoes, black flies, etc. -- around a water source. With the Steripen, I can fill my bottles and move away from the water to purify.
The SteriPen Adventurer - Designed specifically for outdoor and expedition use
No pumping, no chemicals, no test strips, no timekeeping, no lubricating, and no replacement filters are required. Just press the button, dip the SteriPen into your bottle, and wait 90 seconds for it to purify -- up to 8,000 16-ounce treatments.
This water purifier zaps viruses, bacteria, and common protozoa using ultraviolet light to destroy the DNA of microorganisms, making them unable to reproduce and, therefore, unable to cause illness. The SteriPen is effective against giardia and cryptosporidium; pathogens that cause diarrhea, dysentery, hepatitis, and Legionnaire's Disease; household germs such as bird flu, E. coli, and salmonella; staph and strep; and risks from natural disaster, like botulism, cholera, smallpox, and typhoid.
You can purchase a Steripen prefilter if you'll need to remove sediment and particulates from murky water before purifying. It's made to fit the SteriPEN handheld products and gives you better--cleaner--end results. I've seen some hikers use coffee filters and bandanas as prefilters, as well.
Please Share Your Feedback On Steri-Pen
If you've used the Steri-Pen, did it work well for you?
Yes, I liked it.
Not just for the water in your toilet bowl
PRO: It's cheap and readily available.
CON: You'll smell it (unless you can let it sit for a long time, ie overnight, so the smell can dissipate).
For this method, only use regular Clorox Bleach, not the Fresh Scent or Lemon Fresh.
First, let the water stand until visible particles settle out, then pour the clear water into an uncontaminated container and add the bleach. Mix well and wait half an hour. The water actually should have a slight bleach odor. If it doesn't, repeat the dose and wait another 15 minutes, then smell it again. Purifying small amounts requires only a few drops, so an eyedropper is a handy addition to your kit.
- 2 drops of Regular Clorox Bleach per quart
- 8 drops of Regular Clorox Bleach per gallon
- 1/2 teaspoon Regular Clorox Bleach per five gallons
If the water is murky, double the dosages.
Note: Bottles should be replaced every three months to ensure that the bleach is at full strength.
Your Feedback On Using Bleach To Purify
Have you used this method? Did you like it or not?
Yes, I've used it and liked it.
PRO: Chlorine can be used by people with iodine allergies or restrictions.
CON: Like iodine, treating with chlorine takes time, the length dependent on water temperature and sediment level.
I've been trying to find an explanation (in plain English, that is) of the difference between bleach and chlorine. The best I've come up with so far is that chlorine can "bleach" things, but it's not the same thing as what's in a bottle of bleach, which is sodium hypochlorite ... whatever that is. I'll have to hunt for a better answer.
In any case, an example of chlorine water treatment products is Halazone, but apparently reliable disinfection requires 6 tablets per liter for 1 hour of contact, and the tablets rapidly lose effectiveness when exposed to warm, humid air.
Your Feedback On Chlorine
Have you used this method? Tell us why you prefer it or not.
Yes, I've used this method and liked it.
Squeeze or suck the water right through the filter
The Christmas after my Appalachian Trail hike, I found a filter bottle in my stocking, which I thought was pretty neat.
PRO: The all-in-one bottle is compact, convenient, lightweight and simple.
CON: The only con I can think of is that you pretty much have to submerge the bottle to fill it, so you may run into situations where you'll need to use a smaller cup to scoop or some other method to get the water from source to bottle. But this would be the case with just about any treatment method other than filtering through a tube.
Also, the stream of water is fairly small due to the fact it has to be squeezed through the filter. So if you're really thirsty, you can't "chug."
There are many different types of filtration bottles on the market, varying in cost and number of refills before the filter should be considered worn out and the bottle discarded. Check with each manufacturer to get the details on what substances each filter will remove. I honestly don't recall what brand I had, but I know I used it for years and had no problems.
The Clear Brook Portable Filter Bottle, for one, is good for treating 100 gallons (or 750 refills) and capable of up to 99% reduction in all 4 areas of contamination, including offensive tastes, odors, silt, sand and sediment; biological pathogens such as Giardia, Cryptosporidium, and other cysts and spores; chemical VOC's, PCB's, Agricultural SOC's, detergents and pesticides; and dissolved solids, as in heavy metals, Aluminum, Asbestos, Cadmium, Chromium, Copper, Lead, Mercury and Radon 222.
The "No Leak" top, with a collapsible, pop-up straw, can be used either as a squeeze bottle or by drinking through the straw.
The product has been used and tested by International Red Cross, the U.S. Olympic Team, U.S. Coast Guard, and California State approved laboratories.
The LifeSaver Bottle
This is a pricier but much longer-lasting and advanced type of filtration bottle. It was developed by Michael Pritchard after he witnessed the devastation of Hurricane Katrina, apparently pouring his life savings into researching a chemical-free solution that's able to purify 4,000 to 6,000 liters on a single filter.
It's unclear if this device will work on sea water, but it will eliminate bacteria, viruses, parasites, fungi and all sorts of microbiological waterborne pathogens.
The invention won an award from Well-Tech and has a replaceable filter that's good for 5.5 years, based on filtering 2 liters per day. Filtering 750ml of water takes less than a minute, and once the cartridge expires, the unit will shut itself off.
If color matters, this one comes in six options. More importantly, it removes 99.9% of Giardia and Cryptosporidium and filters up to 100 gallons of water, which is equal to about 400 bottles of bottled water.
Your Feedback On Filtration Bottles
Have you used a water filtration product? What did you think?
Yes, I've used one and liked it.
Grapefruit Seed Extract
A non-traditional way of purifying
I can't speak to the pros or cons of this product, because I know little about it. My husband does have a friend who's used it extensively on his backpacking trips and has never gotten sick, but I have no idea if this is directly attributable to the use of the extract. So this is not a recommendation, simply a heads-up that it exists and apparently has many applications, including water treatment.
Grapefruit Seed Extract (or GSE) is a substance derived from the seeds, membranes, and the pulp of grapefruit. It's considered highly effective in fighting infection and promoting health. GSE is used as a purifier, antiseptic, and preservative, with some researchers claiming that it's a superior antimicrobial to chlorine bleach, isopropyl alcohol, and colloidal silver.
For water purification, the recommendation is to add 10 to 25 drops per gallon of water, then shake and let stand for several minutes. The water will have a bitter taste to it.
For more information, visit AppliedHealth.com
Your Feedback On GSE
Have you used GSE? Did you think it was effective or not?
Yes, I used it and liked it.
Some Additional Tips for Treating Water in the Backcountry
- Always carry at least one backup method in case one fails or isn't so convenient. If boiling is your backup, be sure you have enough fuel.
- You don't need to treat water for cooking water or to be used for hot drinks as long as it comes to a rolling boil before you drink it.
- Be sure to use purified water for brushing your teeth. But you won't get Giardia from washing with contaminated water unless you happen to swallow it, so keep your mouth closed if splashing your face. The cysts have to get into your intestines to infect you.
- Consider using a collapsible backpacking bucket or tote to scoop water without disturbing the silty bottom of a stream or spring hole. This keeps the water cleaner for easier filtering. The bucket or tote can be lowered it into areas you may not otherwise be able to reach, and then you can take it back to camp to filter. The bucket is also handy for washing yourself and your clothes and dishes away from sources that could then be contaminated by the wastewater.
Collapsible Buckets And Totes - For bringing water from source to camp
I carried a lightweight tote with me on the Appalachian Trail, so I could not only bring water back to camp for filtering but also to have extra for cooking and washing. Buckets like these are good for murky water, because you can wait and let the sediment settle before filtering.
This one has a 3-gallon capacity and comes with the zippered case you see next to it in the picture here. The bucket reduces to about two inches wide.
© 2009 Deb Kingsbury