From: bonn@networx.com (David Bonn)
Subject: Re: more bad reports on MSR filter
Organization: NetWorx
X-Newsreader: TIN [version 1.1 PL6]
Date: Thu, 8 Oct 1992 16:45:10 GMT

akin@sgi.com (Allen Akin) writes:
> Amazing.  I've used an MSR repeatedly this season, in the Sierra, with
> none of the problems you describe.  Wonder what we're doing differently?

How many days were you out?  How much water did you filter?  It took about
a hundred gallons of filtering to completely clog the final stage.  The scary
part, is with two people cranking back several gallons of water per day, this
translated to a bare three weeks of backpacking.

> Back when I lived in the Seattle area (1982-1985) I heard of several people
> contracting Giardia in the Cascades.  No place is likely to be untouched
> for long.

Certainly that is true.  However, I have spent several recent summers
volunteering in the North Cascades National Park as a backcountry ranger (steep
trails), and out of a group of twenty-odd rangers and about as many trail crew,
there has been one confirmed case of giardia.  There are no katadyn or MSR
filters used by this crowd (neither they nor the government can afford such
fancy things).  Many of them boil water in particularly disgusting cases and
some places.  Much of the backcountry ranger job in the N Cascades is sewage
management -- composting toilets, where you get to dump a yummy bucket into the
composter and stir it (I have pictures!).  These people are out on the trail
between fifty and sixty days between June and September, drinking that water.
You'd think they would be at more risk for G. than the typical hard-core
backpacker who is out about twenty days per season and doesn't have to handle
honey buckets.

I've averaged sixty-plus days of overnight backpacking per season over the last
five seasons.  It is certain that I have been exposed to Giardia and probably
harbor a few in my digestive tract.  We're all part of the food chain and not
always at the top.

The reasons I went with a filter in the Sierras were:  (1) My partner Jim
wanted one, (2) Wilderness managers (both NPS and USFS) in the Sierras don't
beleive in toilets, so human waste would be distributed in many inappropriate
places, (3) different ecology in the water, so any tolerance I might have to
microbes living there would probably be useless, and (4) bigger horse presence
that was also less well-regulated than the Washington Cascades.

Still, one has to wonder if the filters are effective or even necessary.  The
government agencies managing wilderness are so afraid of liability (with good
reason) that they won't tell you if anything is safe.  No outdoor retailer and
no magazine that carries advertising is going to tell you that you don't need
to buy something, are they?

There have been several studies (USGS 1984, Oregon State U, 1989) which have
looked for Giardia and other unfriendly parasites in wilderness.  These studies
indicate that while G. and other fun creatures are commonly found in nearly all
water, concentrations which present any risk are extremely rare.  This raises
an interesting question:  if most water is safe without a filter and you aren't
out that much (thus not rolling the dice that often), how would you know if the
filter had worked or how effective it was at removing microbes?

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