Backcountry Water Treatment

According to conventional wisdom, giarda has invaded the backcountry—from the tallest mountains to the most remote wildernesses—marching from source to source and ready to ambush the weary hiker. Conventional wisdom also says you can defeat these invading microbes with a variety of portable water treatment options. Conventional wisdom, however, is wrong. I'll tell you why and the real key to staying healthy in the backcountry.

  1. The truth about backcountry water sources
  2. The truth about water treatment options
  3. Why experts keep getting it wrong
  4. My dirty little secret
  5. How to identify good and bad water sources
  6. How to grade water
  7. How to manage backcountry water sources
  8. Recommended water treatment options
  9. Follow my suggestions at your own risk
Sawyer filter in action

The Truth About Backcountry Water Sources

Most backcountry water sources are perfectly safe to drink. I thru-hiked both the Appalachian Trail and the Pacific Crest Trail—nearly 5,000 miles in the backcountry—and I did not treat any water. The number of times I got sick: zero. I drank untreated surface water from hundreds of springs, creeks, rivers, lakes and ponds and never got sick.

You might write this off as anecdotal evidence and it is. My point, however, is that conventional wisdom is wrong. If I consumed surface water, on average, every 10 miles, I'd have consumed water from 500 different sources across 17 different states, and if giardia infested even 1% of those water sources, I should have gotten sick five times. I've met hundreds of thru-hikers over the years, and almost all of them have enjoyed untreated surface water and managed to avoid getting sick. Bad water does exist—it's just not as common as conventional wisdom would lead you to believe.

And from a logical standpoint, that makes sense. Bears and deer don't sit around next to creeks pumping water through a filter, but you won't see legions of them wandering around with violent diarrhea either. Wild animals undoubtedly do get sick from time to time, but if animals can thrive on untreated water, so can people.

Alpine Lake
You probably won't find any giardia in this scene!

The Truth About Water Treatment Options

Despite wildly exaggerated claims of the dangers lurking in backcountry water, untreated water still carries a risk. But you have nothing to fear! Today you have an arsenal of weapons to combat bad water from high tech ultraviolet light that sterilizes water to filters that can scoop out contaminats over a hundred times smaller than the width of a human hair. At least that's what the experts would lead you to believe. The truth, however, falls far short.

Water treatment options such as boiling water or using chemicals to purify water can and do kill living organisms in the water, but they won't remove toxins, fertilizers and other unhealthy contaminants. Filters might remove non-organic contaminats—but only if the filter has pore sizes small enough to catch the contaminats.

And no treatment method is 100% effective. That high-tech, ultraviolet light might kill 99.99% of the germs that cause sickness, but that still leaves a few badies around to cause you plenty of intestinal distress. Read the small print—absolutely no devices will guarantee 100% effectiveness. A 99.99% effectiveness rate might sound good, but a liter of water swarming with 10 million giardia microbes means that 1,000 of them will survive to live on and multiply in your small intestines.

Filters have the additional problem of wearing out over time. They may start with a high effectiveness, but after years of use, filters may drop to an 80% effectiveness. Would you want to drink water still teaming with 2 million giardia microbes?

And that's the dirty secret behind water treatment options: They cannot turn bad water good—they can only make it better. The most-effective thing you can do to prevent water-born illness is simply never drinking from contaminated water sources in the first place!

Water does not grow on trees
If you believe that treating water is 100% effective, then I have a water tree to sell you....

Why Experts Keep Getting It Wrong

When I tell people that I don't treat my water, I often gets looks of shock and disbelief. That's understandable—they've been brainwashed. They've probably read hundreds of books and articles describing the dangers of surface water and how to turn bad water into good with proper treatment—the consistent message reinforced by everyone from park rangers to guidebook authors. Surely so many experts can't be wrong! They try to rationalize the discrepancy between the 'facts' that they know and the results I've reported. They'll say I must have an iron stomach, or that I've been lucky.... so far. One woman, so upset by my revelation, said she hoped I'd get sick. I deserved it for not treating my water.

So I'd like to explain why these myths are so persistent and ubiquitous—or at least my suppositions for why so many alleged experts will spout such nonsense. It begins with two kernels of truth: (1) surface water can sometimes make people sick, and (2) the unaided eye cannot see microscopic contaminats.

Then marketers and lawyers rode into town and changed everything. I'm not sure which came first, but they both played important rolls in brainwashing the general public.

Marketers want to scare the bejesus out of anyone venturing into the backcountry because fear is a phenomenally effective method of selling stuff you don't need! They will exaggerate the dangers of surface water with one hand—then immediately sell you a solution to the problem with the other.

The most beautiful part of this tactic: no accountability. If you use their product and do not get sick, they'll claim credit for the success even though you may have never consumed water from contaminated sources in the first place. If you do get sick, they'll blame it on improper treatment, cross-contamination, person-to-person contamination or whatever convenient excuse presents itself. Whatever the cause of your sickness, they will never admit that their product failed you.

Not all the blame can be laid at the feet of marketers, however. Lawyers are a litigious bunch of people—after all, that's their job! You can pull up thousands of books and articles extolling you to treat all water as if your life depended on it, but many of the very people who write these books and articles don't follow their own advice. So why do they put in such disclaimers if they don't actually believe it? Lawyers tell them to do it, and writers have nothing to lose by adding a disclaimer. If the disclaimers are accurate—great! If not.... no harm done. Better safe than sorry! Thus, every major publisher includes a disclaimer about the dangers of untreated surface water.

In a nutshell, almost everyone considered an authority on backcountry etiquette has a vested interest making you believe surface water is inherently dangerous but can be treated effectively.

Untreated water
Somewhere, a lawyer is turning over in his grave.

My Dirty Little Secret

By now, you might want to throw out your filter and drink from that babbling creek to your heart's content, but before you do, I have my own dirty little secret to share: I sometimes treat surface water.

On the Appalachian Trail and Pacific Crest Trail, I did not treat water. Water usually came from sources that I deemed low risk. I carried tablets to purify water in case I needed to use water from a particularly questionable source, but ultimately, I never used them.

On the other hand, I did treat the vast majority of the water I used during my thru-hikes of the Florida Trail and Arizona Trail. Those trails passed by water sources that I usually deemed high risk and I filtered almost all of the water I used. Despite filtering this water, however, I did not consider the water safe to drink. I drank it because bad water is better than no water at all.

I trusted the good-flowing water from high-elevation mountain ranges with limited places for contaminats to enter the watershed than I did in the stagnant, low-elevation sources located among pastures and agricultural lands. Not all water is equal!

So I'm not suggesting that you throw out your filters and stop treating water, but rather to understand the real risks each source might have and select wisely between multiple sources. If you do choose to treat your water, it should be your last line of defense. Good water is safe to drink, treated or otherwise, but bad water can make you sick even if you do treat it.

Water cache to the rescue!
Fortunately, I never had to drink that nasty water from the previous photo. About two miles after I picked it up, I found this water cache! All the treatment in the world wouldn't make the bad water as good as this bottled water!

How to Identify Good and Bad Water Sources

Every water source has a certain level of risk involved, and before you do anything with it, you need to assess that risk. What are the potential sources of contaminats? What contaminats are most likely to be in the water? How concentrated might the contaminats be? Check your topo maps for clues about where the water came from or how long it's been flowing. Take a close look at the water itself. Is it clear or opaque? Are there any dead animals floating in the water? Or does it have a strange smell to it? If it passes the proverbial (and literal) sniff test and you taste the water, does the water taste normal?

In a nutshell, determining the quality of a water source is largely common sense. You'll probably recognize good water when you see it because it looks good, and you'll recognize bad water because it looks bad. But you want specifics, so let's talk specifics:

Check the Water Flow

Choose free-flowing water over stagnant water since free-flowing water doesn't stand still long enough to collect as many contaminats. You'll find two distinctly different types of stagnant water: those that flush and those that don't. Neither option is great, but stagnant water that flushes is preferred over stagnant water that doesn't flush. Pools and puddles left behind in a creek bed get flushed out with every rain storm washing away any contaminats that might have been in the water, but water in a stock pond never gets flushed and could therefore have particularly high concentrations of contaminants.

Bad stagnant water
This stock tank has bad stagnant water because contaminats never get flushed out and grow more concentrated over time.
Good stagnant water
This stagnant water, located at the bottom of a creek bed, likely has few contaminats since every rain storm will flush the water.

Find the Headwaters

Water picks up contaminats as it travels through the countryside, and the longer it travels, the more contaminats it collects—so try to collect water from as close to the headwaters as possible. If you can choose between two different water sources, one that has traveled half a mile from a nearby peak and another that has traveled a hundred miles from a distant mountain range, all else being equal, choose the stream with the closer headwaters.

Pump water
The very best water sources are usually those that you can get right from the source (usually a spring), but pumps are just man-made springs!
Colorado River
Crossing the Colorado River at the bottom of the Grand Canyon is exhilarating and breathtaking, but keep in mind the headwaters begin nearly 1,000 miles upstream and the watershed for this part of the river spans five different states!

Check the Elevation

High elevations often involve steep mountain slopes that discourage development. Industry, agriculture and cities—the primary sources of contaminats—heavily favor low-elevation locations. Not only that, but all water at high elevations cannot have traveled far from its headwaters since water always flows downhill, meaning the water has had fewer opportunities to pick up contaminats. Keep in mind that 'high' elevation is relative. An Appalachian Mountain high could be a Pacific Crest low, but—generally speaking—the higher the water source, the better it is.

High elevation water
Despite the stagnant water, this alpine lake on the flanks of Mount Rainier would seem to be an unlikely source of bad water!
Low elevation water
This well-flowing creek looks nice, but located barely above sea level along the Florida Trail, the water has probably traveled through hundreds of miles of pastures and agricultural land. Drink at your own risk!

Springs, Creeks and Ponds... in that order!

Springs usually produce good water since the ground itself filters the water. Your next best options are usually creeks and streams—especially near the source. Then go for lakes and ponds as a last resort—people tend to camp near and swim in them which could pollute the water.

Speaking of lakes and ponds, I'd like to share my opinion of 'beaver fever.' For whatever reason, beavers seem to have gotten a bad rap for spreading disease. Any animal can spread disease, but I've never heard of any study that shows beavers as being particularly at risk. Once again, I believe conventional wisdom has failed us. I've consumed untreated water from many beaver ponds and have never gotten sick from any of them—an admittedly unscientific test but anecdotally rings true.

Pump water
This spring in Mount Rainier probably has some of the best water you'll find anywhere.
Long Trail Lake
This lake may look nice and serene—and it is! But you will also find campers along the shoreline, hikers swimming in the water and watercraft crossing the lake—all of which can contaminate the water.

Civilization + Water = Bad Water

The single worst thing that can happen to water is to cross paths with human civilization. Whether from farms, pastures, mines, small towns or giant cities, water always comes out the loser.

Assume all water sources that catch runoff from agricultural lands is bad—it'll probably be full of pesticides, herbicides and fertilizers that you shouldn't be consuming.

Cattle, sheep, horses, mules and other farm animals will defecate, pee and even die in water sources. They could be pumped full of antibiotics or steroids, which eventually leach into the surface water.

Mining operations often use harsh chemicals to separate the minerals from the waste rock that leach into the ground water.

When water reaches a city or town, however, it has hit the motherload of pollution. People fertilize their lawns, oil from poorly maintained vehicles leak and drains into creeks and soap from people washing their cars run into storm drains. People dump waste into gutters, dogs defecate by water sources and the list of potential contaminats is endless!

Avoid surface water downstream of civilization and your chances of getting sick fall dramatically, but if you travel through a location where all water sources may have contaminats, try to collect water from sources that have traveled through the least amount of civilization.

Sunflower fields
This scenic field of sunflowers also tells a story of pesticides and fertilizers that could pollute all water downstream of it.
Sheep pastures
Another pastoral scene of grazing sheep, but remember—these sheep might be pumped full of antibiotics or steroids and will contaminate water sources when they defecate, pee and die.
Dead cow in water
Animals really do die in the water sources—and you really don't want to drink such water!

Avoid Water That Looks, Smells and Tastes Bad

If the water looks, smells or tastes bad, it probably is bad.

Be suspicious of any water with an unusually large amount of algae—algae can thrive on contaminated runoff from farms.

But also be suspicious of any water with absolutely nothing growing in it all. Life thrives in water and if nothing at all can survive in the water, you should ask yourself why. Toxic chemicals from upstream mines may have poisoned the water.

The presence of foam on the water's surface often indicates agricultural or industrial runoff.

Sometimes you'll find water colored like diluted root beer—especially later in the summer and early fall. This is tannic acid, leached from trees and other organic growths. In such weak concentrations, tannic acid poses no health risk so don't let that scare you off from it, but neither will it purify the water.

Creek with glacial flour
Glacial flour (fine-grained, silt-sized particles of rock) clouds this river. You probably shouldn't drink this stuff!
Just ignore those tadpoles!
Tadpoles swimming around this water shouldn't alarm you—in fact, it could indicate that the water is safe to drink!
Too much algae!
The water itself looks good, but watch out for the unusually large quantities of algae. This creek flowed through downtown Flagstaff and my databook called the water non-potable and untreatable.
Creek with tannic acid
Usually when water looks bad, it is bad—but this water is an exception. The diluted root beer look marks it as tannic acid and not a threat to otherwise safe drinking water.

How To Grade Water

We've discussed ways to identify good and bad water sources, but now we will take it one step further and learn how to grade the water quality so we can compare two different water sources. This becomes important when it comes time to managing our water sources. You'll find a certain subjectivity involved with grading water, but don't let that discourage you!

A-Grade Water

A-graded water sources generally come from the source: springs, pumps, snow and rain. Because you've taken it from the source, the chance of contamination is small. If you see a source of possible contamination (e.g. a dead mouse in the water, yellow snow, etc.), downgrade the water appropriately. Although not normally found in the backcountry, also include bottled water and tap water as A-graded water. (Tap water in developing countries may not deserve an A, but in the United States, Canada, Western Europe, etc. the water is usually safe for consumption.)

Spring water
The most common source of A-graded water in the backcountry are springs. It doesn't matter if someone has stuck a pipe in the ground to make the water easier to collect or not—spring water, unless you have a specific reason to believe otherwise, is usually as safe as it gets.
Water pump
You usually won't see water pumps in the backcountry, but they always get my vote of approval!
Rain water
When it rains, set up a tarp to direct the rain water into your water reservoirs, or find natural places like these cliffs where you can easily collect rain water.
Crater Lake snow
The waters of Crater Lake are famous for their purity, but the snow that feeds it is even better! Just make sure to only collect white snow!
Water cache
On the Arizona Trail, the most common A-graded water came from water caches!

B-Grade Water

B-rated water usually comes from creeks and streams located upstream of all known human development. The water looks good, smells good and no known sources of contaminats drain into the water. The lack of a complete visual check all the way to the water's source means unidentified sources of pollution could make the water unsafe to drink.

Creek water
I'd have no qualms about drinking from this alpine creek in the High Sierra!
Wildlife trick tank
Despite the stagnant water in this wildlife trick tank, I gave the water a B since all of the water came from the immediate (and undeveloped) area and includes a roof to protect the water quality.

C-Grade Water

C-rated water usually comes from ponds, lakes and other large bodies of water located upstream of all known human developments, as well as any creeks and streams that flow out of such bodies of water. The water probably has some level of contaminats—but probably not enough to make the water unfit to drink. As you might sometimes hear, "The solution to pollution is dilution." The relatively large size of ponds and lakes to such small amounts of pollution should keep the water safe to drink.

The water looks good and smells good, and you have no reason to believe that the water is contaminated—at least nothing worse than the occasional hiker who takes a swim or washes their dishes/clothes/whatevers in the water.

Lake water
Despite the naked man who took a swim in this lake, I'd still give it a C. The lake probably does have contaminats from hikers, campers and swimmers, but the large body of water should dilute any contaminats to safe levels.
Ice water
If contaminats from swimmers are a concern, lakes with large chunks of snow and ice probably have fewer people swimming in them—and even when they do, the swimmers probably don't stay in the water as long!

D-Grade Water

D-grade water usually comes from stagnant water sources (especially those that never get flushed) or water sources located downstream of civilization. The water still appears good and safe to drink, but you recognize the fact that large concentrations of pollutants may be in the water anyhow.

Stagnant water
Just by looking at this water, I can't see anything that looks especially concerning. However, the water is stagnant and although I didn't see any evidence of cattle in the immediate area, I couldn't be certain that such areas didn't drain into here.
Swamp water
This water along the Florida Trail probably traveled countless miles through cattle ranches and farms. Although the water itself seems fine, hikers should assume the worst.

F-Grade Water

Any water source that you know contains significant levels of pollution gets an F. F-graded water is most often located below civilization and involves stagnant water, but you can find it anywhere. If you see dead animals floating in the water, give it an F. If you see cow patties surrounding a stock pond, give that water an F. Any water source that smells strange or tastes funny—give it an F. You get the idea!

Dead cow in water
Dead animals in the water are an automatic F!
Bad stagnant water
Stagnant stock pond surrounded by cow patties—definitely an F!

If you treat water, bump it up one grade. I've passed D-rated water where I've seen hoards of hikers stop to fill up. They treated the water, but I chose to hike on another 5 miles to pick up water from a B-graded source further up the trail. Later, some of those same people grew sick while I stayed perfectly healthy. Some seemed surprised they got sick because they always studiously treated their water, but I didn't find it surprising at all—they drank crap water and treatment did not make it good. At best, treating D-water can only turn it into C-water—and why you should only use water from the very best sources available.

How to Manage Backcountry Water Sources

The key to staying healthy is simple: Only drink from the best-rated water sources... then trade up at every opportunity.

A-graded water is the gold-standard for good water, but sometimes you must settle for less. Fill up with the best-graded water you can, and try to carry enough to get you to the next water source with an equal grade or better.

If you arrive at a water source graded better than the water you currently have, trade up! Dump out the worse water and replace it with the better water. Replace C-rated water with B-rated water, then replace the B-rated water with A-rated water. Keep trading up!

On some trails, you might not be left with any good options. I would still pick a D-rated water source over an F-rated source, but neither option leaves me smiling.

On the Florida and Arizona Trails, good water is scarce! I'd often leave trail towns with gallons of tap water on my back so I could avoid drinking all surface water for two full days. When I did have to drink from less than pleasant water sources, I always treated it. You can't turn bad water good, but you can make it slightly less toxic! And, of course, I upgraded at every opportunity. If I saw a B or C-graded water source, I'd fill up with a couple of gallons and try to stretch it out for a couple of days to avoid upcoming stretches filled with D and F-graded water.

Another backcountry trick of mine: I cook dinner most nights and that requires me to boil water, so I'll use the worst-graded water in my arsenal for that purpose. If I carried a liter of A-graded water into a campsite with a B-graded creek running nearby, I'll use the B-graded water for dinner since it'll get boiled and save the A-graded water for drinking straight. Always trade up every opportunity you get, but if you can't trade up, at least use the worst water for boiling. In such a scenario, you can also clean your dishes with the worse, B-graded water. It will "contaminate" your dishes with B-graded water, but that's still better than drinking the B-graded water directly because you ran out of A-graded water washing your dishes!

And that's the best way to avoid water-born illnesses: Drink from the best water sources available, avoid the worst water sources as much as possible, trade up at every opportunity—and rely on water treatment as a last resort. You might still get sick from a water-borne illness, but at least you have stacked the deck in your favor!

Pick the best water sources available
Here, you essentially have two different water sources to choose from—the spring water dribbling out into the tank or the largely stagnant water that's been in the tank for weeks or months. I filled up my water with the better option—the stuff coming directly from the spring!
Trading up from bad water to good water
On the Arizona Trail, I was forced to take water from a nasty stock pond—I bet you'll have no trouble figuring out which of these water sources came from the stock pond! When I came across this unexpected water cache, however, I dumped out the nasty water and replaced it with the water from the cache! Most of your trades won't be this dramatic, but even small upgrades help!

Follow My Suggestions At Your Own Risk

With about 10,000 miles of backpacking under my belt and drinking untreated water for over 5,000 miles of them, I've managed to avoid getting sick... so far! I make absolutely no guarantees that you'll see the same results. Nor should you take my advice as an endorsement for not treating surface water in the backcountry. I don't treat water when I feel the water sources are good only because I'm inherently lazy and choose to assume the risk.

The facts that I believe are true and the experts get wrong over and over again:

  • Giardia is not as common as conventional wisdom would lead you to believe. A sort of hysteria swirls around giardia that's not supported by the facts.
  • No portable water treatment methods can turn bad water into good water.
  • Using your brain is a far better tactic to staying well and healthy than depending on water treatment devices. However, do use water treatment devices to supplement your brain power.
  • Drinking any surface water entails a risk. You can beat the odds for a long time if you do it right, but eventually your number will come up. Nobody, no matter how careful, will escape the wrath of surface water if you consume it often enough. I've made it 10,000 miles without getting sick, but eventually, my streak will end. I'll probably update this document to tell you all of the gory details after it happens too!
  • Far more hikers get sick due to poor hygiene than bad water. Use a hand-sanitizer after going to the bathroom or before handling food. Don't let friends take Skittles out of your bag—pour it out into their hands so they can't contaminate it.
Bathtube spring
Bathtub Spring is one of the more unusual water sources I've come across during my travels!