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Re: [at-l] Water treatment

This is definately a case where being "burdened with actual knowledge" will
help you understand why filtration works, and exactly what you are filtering
with the particular filter you choose to use. All filters are not created
equal. Not by a long shot. Some will not even reliably remove giardia...

There are filters what use active charcoal and other chemical binding methods,
filters that simply use very small holes, larger than water but smaller than
viruses and most nasties, and filters that use iodine to poison living cells
while still letting them through into your water.

Many filters do not filter pesticides and heavy metals. They are not designed
to do so.  Some are, generally through molecular and chemical binding
processes, not filtration.  Many do not remove viruses, only the most common
"pests" like crypto and giardia.  The term filter actually is incorrectly
applied to what we carry, as filtration is not the only function these devices
use to clean our water. Some are purifiers, some chemical treatment systems,
and all share some level of filtration.  It's the chemistry of these methods
that bind many of the impurities, not some magical molecular filter that lets
water through and blocks DDT.

As for the spread of giardia, it is a human-borne disease that some animals
are also capable of carrying - most notably the beaver.  We brought it into
the woods and left it behind in our feces where it contaminated the water we
drink.  This disease was virtually unknown in the wild 30 years ago. The most
commonly infected group of people with giardia are daycare workers, not
hikers.  This according to the CDC in Atlanta.

There are some really great references on the web that talk about filtering,
diseases and water quality in general if you would like to improve your level
of knowledge.

The people who choose to drink untreated water may not get sick at all. I have
been - once - and now I won't take the risk where there is any chance of contamination.

-Paddler (GA>ME 99)
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