Earlier today, I was talking about the PCT with some friends of my family, and they started asking me about the terrifying wildlife I might see along the trail. Their worries were of encounters with rattlesnakes, scorpions, and bears. Honestly, it’s not those creatures that make me anxious; if my battle with Lyme Disease has taught me anything, it’s that it’s the little guys that you’ve got to be afraid of: ticks, the air-borne fungus that causes Valley Fever, and Giardia. 
I’m of the opinion that, anytime you’re dealing with living creatures, it’s impossible to speak in terms of absolutes. I doubt that a certain series of behaviors could completely prevent the contraction of Giardia; however, there are some behaviors that can mitigate your risk.
First of all, there’s personal hygiene. In thinking about how to be clean in the woods, I’m reminded of Disney’s Mulan: “Just because I look like a man doesn’t mean I have to smell like one.”
I know a couple people who, when they’re backpacking, are capable of looking like they just stepped into the woods for a day-hike. Most of us aren’t that lucky. Fortunately, you don’t have to look like part of an REI ad to lessen your risk of contracting Giardia.
At the risk of sounding like a preschool teacher, the best thing you can do is keep your hands clean. Clean them after cat-holing and before eating. Wet Ones and alcohol swabs are perennial favorites for many hikers; just be certain to pack out any wipes you use.
That said, the fact is that your own body’s cooties are far less likely to make you sick than those from another person. And, that’s why there’s a saying on the trail that Booksmarts taught me back in 2011: “The communal gorp bag is poured from, not reached into.” If you’re fortunate enough to be on the receiving end of some trail magic from another hiker, don’t stick your hand into the bag to extract some Reese’s Pieces, blueberries, or Swedish Fish. Instead, pour out a handful.
Since Giardia can be water-borne, choosing water sources carefully goes a long way toward reducing a backpacker’s risk of getting sick. I remember meeting two young guys early on my hike of the Appalachian Trail who were excited to get to a river that we were due to cross later that morning, since that’s where they were planning to fill up their water bottles. I questioned their plan, suggesting drinking from any of the little streams and springs we’d be passing before then, but they explained that they love quick-flowing, large sources of water.
In my mind, the Potomac, which flows very quickly and is very large, is not the paragon of water sources.
Small sources draining small watersheds can be very good water sources. It’s important to consider the watershed that is supporting a given water source. Does the land around the water seem healthy? Is there a good plant cover (i.e., grasses, herbaceous plants, etc.) that filters rainwater? Are there any dead animals or obvious animal fecal matter in the vicinity? Are there cow pastures or herbicide/pesticide-laden farm fields upstream? Be water-aware, and you’re likely to find good drinking water.
Most thru-hikers will agree that one of their favorite things about long-distance hiking is tasting water from mountain springs. Fresh, cold water is such a simple gift, but it’s something we certainly appreciate. Some springs have dramatic flow rates, where water gushes out of rock (sometimes through a channeling pipe, soda bottle, or curled leaf. Other springs just look like puddles of water.
While stagnant water is not a preferable water source, the puddle-variety of spring, with a steady stream of “new” water bubbling up from the earth, is great.
Now, I say all this, and in a couple months I’ll be departing on the Pacific Crest Trail, where water sources include a cattle trough, several horse- and cattle-frequented streams, and cisterns where chipmunks have drowned. A number of ultralight hikers insist on hiking sans water treatment, but I know that my compromised immune system would never tolerate that.
I definitely have enjoyed live water when I have seen a spring’s source or in some unfrequented high elevation streams; however, Giardia and its partner-in-crime, Crytosporidium, have been cultured and contracted from even these sorts of water sources, as several of my hiking friends and this blogger can attest to.
Some hikers feel that being cautious about hygiene and water sources takes some of the fun out of backpacking and leaves them feeling out-of-touch with the natural world. I appreciate that perspective, but, especially because of my tendency to get sick easily, I’d rather take risks in climbing Mount Whitney, attempting consecutive “marathon days,” crossing snowmelt-swollen streams, and meeting new people while hiking and hitchhiking. And, I’ve really had it with microbes.
Fellow hikers, have you had any run-ins with microbes while in the backcountry? How do you avoid them?
Wanderstruck Studio 
You say you’ll be cleaning your hands, but you don’t specify what sort of water treatment you plan to use. For my thru-hike last year I started with a Sawyer Mini, but was disappointed with the output flow. After a while it was taking me 6-7 minutes to filter one 0.7L bottle of water even after I had back flushed it. Also I was needing a new squeeze bottle about every 400 miles because they would split near the top. So in time I got a Sawyer Squeeze (regular size) and used a Pepsi/Desani 1L plastic bottle. This bottle required me to squeeze and then release the pressure, but I didn’t find that bothersome, and the rigid bottle was easier to fill than the floppy squeeze bag. Overall I filtered about 90% of the time. I didn’t always during the time I had the Sawyer Mini because it took so long to filter. However once I got the regular size one, I filtered from then on out. Bottom line, I was never sick with a water borne illness. Sincerely, Tartan PCT 2014
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Good question, Tartan! I actually intentionally left out that detail because I didn’t feel qualified to comment on the effectiveness of various filters.
That said, I loved the Katadyn filters I’ve hiked thousands of miles with. I’ve found them non-fussy, straightforward, and effective.
I’ve never used the Sawyer Mini, but I’ll be using the regular Sawyer Squeeze on the PCT. I’ve used it for five hundred miles or so, but I don’t like it. I understand that it’s supposed to filter more efficiently than just about anything else, but I don’t like squeezing, its fragility in cold weather worries me, and I don’t like that it can’t be taken apart for cleaning. I’ll be carrying it because of its filtering prowess and its light weight.
Does that clarify things?
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“In my mind, the Potomac, which flows very quickly and is very large, is not the paragon of water sources.” So true!
Good for you for being so pragmatic.
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