I have become a little fascinated with water purity while camping and hiking.  The official term for this is "potable" water - with a "long" O. 

My earliest  training in the 1960s from my father was to be very careful about water.  Really bad things could happen if you drank water from a creek and did not know where the creek came from.  I grew up in Kentucky, and it was all too likely for one to become infected with hepatitis A from drinking water contaminated from a septic tank somewhere.    But my dad also taught me that if water was aerated by coming down a stream bed and did not have any septic drainage, it was likely OK for drinking. 

Later in life I learned all about water purity in deployed military operations, ensuring the "potability" of water, and the consequences of a whole unit coming down with illness from water. 

During family vacations in the Boundary Waters Canoe Area (BWCA) in the 1970s, the rule was not to drink water from lakes with cabins, but water from clear lakes without permanent settlement should be OK for drinking.  Each person had a cup tied off to the thwart in front of them and when they became thirsty, they dipped it in the lake to relieve their thirst.

By the year 1990, much had changed.  I learned in survival school how all water in the high woods needed to be purified.  My medical chart was stamped by the medical staff that I had spent 3 weeks in a survival camp and that if any symptoms kicked up over the next month, the doctor should consider giardiasis as a possible cause.

On a trip in 2001 to the BWCA, I carefully filtered all the water my son and I drank with a Sweetwater Guardian.  Same on a follow-on trip in 2002.  A whole technology developed about water filtering...  we had the filters of course, we could filter water out in the middle of the lake from a canoe.  We could get water in a basin and carry it up to the fire ring to be able to sit down comfortably to filter the water for the 5-10 minutes that 2 quarts took. 

I still have the filter to the Guardian in my freezer at home.

Winter of 2002-2003, I began to think along the lines of decreasing the weight and go a more lightweight approach to backpacking and kayaking.  I learned about PolarPure, a dispensing system for iodine which is effective against viruses as well as Giardia lamblia.  But I also learned something about Giardia which was unexpected:  It may not be nearly the problem it is made out to be. 

Every official forest service circular, every trail guide, the CDC in Atlanta in it's MMWR, all of them are quite clear:  There is an epidemic of giardiasis among backpackers.  Every outdoorsman knows this.  Every scout it taught this.  But is it true?? 

I began to doubt the veracity of the claim when I found as part of a little (and rather nonscientific) survey some data suggesting that of thru hikers on the Appalachian Trail (AT), it did not seem to matter much whether the hikers used water filters, chlorine, iodine, or nothing - all groups had about the same likelihood of having a case of giardiasis (2 percent) or gastroenteritis (20 percent).  First look at these data suggested to me that the methods to purify water were just not good enough to prevent the illness.  Second look (suggested by others, and a better explanation) is that the source of giardiasis is not the water.  

But OF COURSE the  source of Giardia lamblia is the water.  Everyone know that! 

Well....  maybe not.

There is another side of the argument.  For several years, individuals have been pointing out that there is really very little evidence that Giardia is being spread by water in mountain streams.  (or from the lakes of the BWCA) I have gathered 3 articles below which are worth reading.  The first is from an experienced mountain climber and retired Aerospace Engineer.  I find it well researched.  The second and third articles are from the journal of Wilderness Medicine and are even more current. 

In essence, they show that

 - there is not a heavy burden of Giardia in mountain waters

 - the risk of being infected from those waters is very small

 - the oft quoted studies (2 of them) showing giardiasis among outdoorsmen were likely from shared food, not mountain waters

 - the cause of giardiasis among backpackers may be contaminated food, not water

  -- the cause of the food contamination is the hikers not washing their hands before fixing it

 - the prevention of giardiasis is to be found in good personal hygiene and food preparation hygiene

Here they are for your consideration:  Agree or not, I believe that reading this information will give you a better understanding of the problem and possible approaches to remaining healthy during an extended time in the woods.

By Robert Rockwell,

http://www.yosemite.org/naturenotes/Giardia.htm#_edn2 

This article is also available at numerous other sites on the net if you search for Robert Rockwell and Giardia

And the two articles from Wilderness Medicine:

Giardia in the Desolation Wilderness near Tahoe

Giardia as a Threat to Backpackers in the US

Risk's Ultralite Hiking Page

Flyfisher  Home