So, everyone you talk to will tell you that it's (in a basso important voice) "Very important to purify your water when in the backcountry". Okay... great. And before we get rolling, let me be clear, I'm not saying to stop doing that! Your risk, your body, your hike. I just want to explain the facts, and my views on the issue.
Now, try backpacking in the Sierra and chatting with some of the Rangers who've worked up there 20 or 30 years. Guess what? A lot of them don't treat their water.
Okay, so why the disconnect, what's going on here?
I'm going to leave cryptosporidium out of the conversation entirely, as most popular filters in the US don't work for it anyway, it's a moot point. So lets focus on Giardia, as that's the one everyone is always worried about. Note though that there are a LOT of bacterials, a lot a lot, and that these are more common than Giardia. You should be suspicious whenever a friend says "Oh yeah, I got giardia once, on this weekend trip from drinking the water, we had to leave the next day". Giardia's onset is not 24-48 hours, it's more like a week (see facts/citations below). Gastrointestinal problems can be a pile of different things. Shigella bacteria for example.
- Giardia is basically limited to the digestive tract 
- Giardia rarely hits you in less than a week , but can occur after 3 days 
- Giardia is the most common NON-BACTERIAL cause of gastro-intestinal diseas 
- Giardia can be caused by as few as 10 human sourced giardia cysts 
- Giardia is highly temperature sensitive. Both cold and warm temperatures kill it. 
- Giardia can cause no symptoms at all 
- Ill effects for healthy individuals are restricted to discomfort, dehydration, and vitimin deficiencies. 
- Standard treatment is a round of antibiotics , though healthy individuals usually pass it within a month 
- The disease is most infectious within a species, but does appear to species jump fairly easilly 
- Giardia is primarilly acquired via ingestion of infected human waste 
- Untreated Giardia can cause more interesting complications 
- Most of the symptoms of Giardia can be caused by dehydration - my citation? If you've been badly dehydrated you know what I'm talking about.
- I'm having trouble finding the citation now, but there have been a couple studies done basically saying that the vast majority of all cases are human-human direct cross contamination. This was particularly in the setting of backpacking. Additionally some water studies have found that while it is there in some rivers, it's not incredibly common.
My thoughtsTo me, drinking water directly from a river or lake is a very important experience. It's a spiritual or religious thing for me. For the same reason as I try and reduce my gear such as on my recent Lassen trip. When I went back to find my knife, I knew that place. I had bonded with it deeply, spiritually. Every piece of equipment and gear between me and that environment gets in the way of that experience for me. The feeling is stronger with a locally built shelter than a tarp, and stronger with a tarp than a tent. So, to me, it's worth a certain risk - even beyond weight savings - to drink the water straight.
Giardia is very easy to treat. I'm having trouble finding a reliable citation, but there's a LOT of anacdotal evidence that grapefruit seed extract (as well as a number of other simple treatments) are extremely effective. There are no lasting problems if it's fully cured, and some people even become immune .
So, will I get sick from Giardia or something else in the water? Yeah, it's not unlikely. On the other hand, most likely I'll treat it, be sick for a week, and that'll be that. To me, that's worth a lifetime of drinking pure sweet water straight from the source, and not fiddling with gadgets to do it. We'll see if my opinions change if I get sick.
And for gosh sakes, if you are going to go to all of the work to treat your water, Wash your hands!. Wash with water (and not in the stream... duh), and some soap. Interestingly actually, water is more important than soap.
My point here is just to say, consider the risks. This is always true, but when it comes to "medical" conditions people seem to shut off their brains and just listen to what they are told. Think about not only how likely something is to occur, but how bad would it be if it did? And *reconsider* for different places you might be. The risk of getting Giardia in the Sierra is relatively low, but where there are beavers, or worse muskrats , it increases. Outside the US is a whole different ballgame. The likely result is also a lot worse if you flew deep into Alaska by bushplane, and don't know any local treatments or have the right stuff, than if you're on a weekend trip and it won't matter until next week when you'll have to take 2 days off work and sit on the toilet a lot.
One more little point. If you are thirsty and you are not going to get pure water soon... seriously, consider the alternative to drinking that water? I personally drank from what amounts to a hog-wallow without treating (I actually scared the hogs off). I am alive here today, and in fact didn't even get sick. I'm not sure how I would've faired against the heat-stroke had I not drank that water, probably poorly.
So, as always. HYOH (Hike your own hike), make your own decisions, judge the risk for yourself, and deal with the results of those decisions.
- 1: http://www.who.int/ith/diseases/giardiasis/en/index.html
- 2: http://diarrhea.emedtv.com/giardia/giardia-facts.html
- 3: http://www.rightdiagnosis.com/g/giardia/stats.htm
- 4: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDEQFjAB&url=http%3A%2F%2Fwater.epa.gov%2Faction%2Fadvisories%2Fdrinking%2Fupload%2F2009_02_03_criteria_humanhealth_microbial_giardiafs.pdf&ei=2NAfUt6yCMn5iwKS2YHoAQ&usg=AFQjCNEmHfmYayouSXiZPx5sqWwilOuLQw&bvm=bv.51495398,d.cGE&cad=rja
- 5: http://www.cdc.gov/mmwr/preview/mmwrhtml/ss6105a2.htm
- 6: http://www.bccdc.ca/dis-cond/a-z/_g/Giardiasis/overview/Giardiasis.htm
Here Beaver are common and finding toilet-paper near a stream is sadly a daily occurrence. So, living out here I do treat my water. I may change my mind again, but for the time being I'm taking the conservative approach.
Look at where you go, get educated, decide what risks you want to take, and make your own decision. If you don't want to do all that, just filter and don't worry about it.
I've actually returned to drinking almost entirely untreated water, even on the east coast. I still haven't gotten sick. Since Angie and I hit the road we've barely treated our water. We drank water straight from lake Michigan, as well as random streams, rivers, and lakes in the Ozarks, Adirondacks, Green Mountains, and White Mountains.