Editor’s note: A couple of weeks ago, after we published an article on how to prepare for the Wakely Dam Ultra that noted the necessity of treating water taken from backcountry sources, Erik Schlimmer contacted us about his research on Giardia. He argues that the risk of acquiring Giardia from a backcountry water source is negligible, meaning that—in most cases—there’s no need to treat the water. He writes below about his review of the scientific literature and his experience in the backcountry, raising the question of whether treating water really is necessary.
By Erik Schlimmer
There are many things outdoors experts and enthusiasts agree on. For example, a warm meal feels great at the end of a long day on the trail. Cotton fabrics take forever to dry in the field and should thus be avoided. Mosquitoes and black flies come straight from hell. And all backcountry water must be treated (that is, filtered, purified, boiled, or subjected to chemicals or ultraviolet light) due to the presence of Giardia. Giardia, a protozoan, has infested water sources, causing hikers who do not treat their water to suffer from giardiasis, a debilitating gastrointestinal illness.
There is no denying that hot meals are soothing, cotton is inferior, and camping during bug season is cruel and unusual punishment. But has Giardia really infested our backcountry water sources? Ask this question to nearly any lover of the outdoors, and you will receive a harried, “Oh, yes it has!” To the above question I calmly answer, “No, it has not.” I share an evidence-based view that embraces drinking straight from the source. The supporting evidence for not treating backcountry water is presented in five myth-busting arguments that will encourage you to look at your water sources differently.
Safety in (lack of) numbers
Despite popular belief, water sources are not crawling with Giardia, as proven by a 1984 examination of nearly 70 Sierra Nevada water sources. This research project performed by the United States Geological Survey and California Department of Public Health drew two interesting conclusions.
First, data showed that more than 55 percent of high-use sources and nearly 85 percent of low-use sources had no Giardia cysts. Second, of the sources that had cysts, the amount was ridiculously low—nowhere near enough to make you sick, considering you must ingest approximately 20 viable cysts to develop giardiasis. As a portion of this study nearly 1,000 gallons of water were filtered from ten different sources, but fewer than 150 Giardia cysts were found.
If you demand more recent research look no further than Backpacker‘s 2003 article “What’s in the Water?” Backpacker staff collected three samples from seven sources. Five of their samples had no Giardia cysts and the most polluted sample had only 0.8 cysts per liter. Most cysts were deemed unviable.
The New York City Department of Environmental Protection (DEP) follows trends presented by the two studies above. As part of their Cryptosporidium and Giardia Monitoring Program, the DEP annually publishes results of their searches for Giardia. During 2008 they collected 164 50-liter samples of untreated water from six reservoir locations. Thirty percent of the DEP samples had no Giardia cysts. When cysts were present, there were fewer than 2 per 50 liters. Additionally, the DEP cautions that cysts found were likely not viable.
Myth busted: Giardia is prevalent in backcountry water.
Are You Sure it Wasn’t the Sushi?
When a backpacker tells me he got giardiasis, I have only one question for him: “So, your doctor told you that you had giardiasis?”
The answer invariably is, “No… I mean, uh, I didn’t get tested—but I’m sure it was giardiasis!” Self-diagnosis perpetuates the Giardia myth. As eminent European long-distance hiker Chris Townsend reveals in The Backpacker’s Handbook: “People who tend to get a gut disorder tend to blame Giardia in the water because they’ve been warned about it, even though the cause is probably not either Giardia or the water.”
In an article published in Sierra Nature Notes, mountaineer Robert Rockwell agrees: “The diarrhea being blamed on Giardia from that climbing trip a week ago may instead be due to some spoiled food eaten last night or [bacteria] in undercooked chicken four days ago.”
Steven Zell, a physician and researcher, writes in the Journal of Wilderness Medicine that the medical community is chronically misdiagnosing by “empirically treating [wilderness-acquired diarrhea] cases for giardiasis without demanding laboratory confirmation.”
Thomas Welch, a physician at SUNY Upstate Medical University, agrees with Zell: “Most non-specialist physicians who have been out of training for a long time don’t know much more about giardiasis than your average outdoor educator. To them it’s straightforward: diarrhea after a camping trip? Giardiasis! The treatment is easy, so they just give it. However, most cases of diarrhea go away after several days anyway, so the patient would get better no matter what.”
Myth busted: If you get sick after a camping trip it’s because you have giardiasis.
Disregard Nonobjective Parties
One water filter advertisement warns, “No water sources should be considered safe to drink without treatment.” Companies that sell water treatment products only benefit from spreading rumor.
Federal and state agencies fear the L word: liability. Townsend, in The Backpacker’s Handbook, argues, “To cover themselves, land managers generally advise people that all water needs treating.”
Welch feels aggressive trailhead postings are uncalled for. In a 1997 issue of Adirondac, he writes, “Upon passing any of the busy entrances to the [Adirondack] High Peaks on a summer day, one could easily get the idea he or she was coming into an area whose water quality approximates that of Bangladesh.”
In James Wilkerson’s Medicine for Mountaineering, Fred Darvill agrees: “Frantic alarms about the perils of giardiasis have aroused exaggerated concern about this infestation. Governmental agencies . . . have filtered hundreds of gallons of water, found one or two organisms (far less than enough to be infective), and erected garish signs proclaiming the water ‘hazardous.'”
What are Giardia warnings based on? I wonder, and Welch wonders, too, reminding us that “there is not a single peer-reviewed report proving the acquisition of giardiasis from consumption of backcountry water in the U.S.”
Myth busted: Interested parties report the facts about Giardia.
The Real Culprits
Roland Mueser, author of Long Distance Hiking: Lessons from the Appalachian Trail, completed a trailside study that became the core of this book. During his own Appalachian Trail hike in 1995 he asked thru-hikers a catalog of questions, from how many miles per day they averaged to whether they smoked. Two questions he asked that pertain to giardiasis were whether the thru-hikers treated their water and whether they experienced gastrointestinal illness during their hike. Mueser made contact with 136 thru-hikers. Some of them boiled their water, some used a chemical treatment, some used a filter, and some did not treat their water at all. Here are the numbers:
|How often they treated their water||Percentage who became ill|
As Mueser deduces, “It seems probable that some systematic explanation for gastrointestinal illness [lies] beyond the simple water-purification process.” Further reading reveals that these Appalachian Trail thru-hikers suffered food-borne illnesses and became sick because they did not wash their hands. Our hands are the primary vector for spreading disease. The authors of The Backcountry Classroom also cite Thomas Welch: “In the United States, the vast majority of cases of giardiasis are caused by hand-to-mouth spread. . . . No studies have shown that consumption of backcountry water in North America is an important cause of this disease.”
Myth busted: Untreated water is the primary source of illness in the backcountry.
Lab Rats Don’t Lie
By this point perhaps some of you are asking, “Well, Schlimmer, if the water is so safe, why don’t you drink 100 quarts of untreated water?” I’m way ahead of you. Since June 2006, I have not treated my water and have experienced no signs of giardiasis despite drinking more than 600 quarts across nine states. By my 200th quart I was wholly convinced of Giardia’s absence in backcountry water and decided to bring a discussion of water treatment into my day job, empowering my own outdoor education students and instructors. For years I distributed articles cited above and let them decide: to treat or not to treat? I witnessed my students and instructors drink more than 1,300 quarts, and no one who chose to drink their water straight contracted giardiasis.
Myth busted: If you drink untreated water you’ll get giardiasis.
The final issue is this: Why? Why should we embrace drinking straight from the source and then share the fact that water sources are not permeated with Giardia? The answers to this question come from my perspective as an educator.
One, presenting rumor as fact undermines education. Authors like me are supposed to know their stuff; through this we serve as mentors. If we tell readers that water needs to be treated and then these readers consult scholarly articles that suggest otherwise, we have committed a disservice.
Two, I would rather have you do something more productive with your time in the great outdoors than treat water, an activity proven unnecessary most of the time. Instead, you can take that time to complete a map check, enjoy the view, or care for your feet.
But you need to examine water sources logically (and keep in mind that no water source can be guaranteed safe). Seek clear and cold springs as well as pristine streams, lakes, and ponds in the backcountry. Though it may sound too simple, backcountry sources that look, taste, and smell good are good. You should avoid sources that look questionable. Excessive algae, discolored water, discolored shorelines, bad smells, completely stagnant water, a lack of aquatic growth and insects, shorelines that host heavy backpacker or animal use, or any combination thereof are bad signs.
As an author and just a good old fashioned lover of the outdoors, I have a unique opportunity—no, an obligation—to educate others who call the outdoors home. With authors agreeing that hot meals are welcome and that cotton and antagonistic insects come from Lucifer, it’s time to discuss our commonalities over a tall glass of untreated water, with little concern for giardiasis.
Erik Schlimmer is founding member of Friends of the Trans Adirondack Route and author of Blue Line to Blue Line: The Official Guide to the Trans Adirondack Route.