Scouts-L Mail Archive for October of 1998: Re: Water Purifiers
Re: Water Purifiers
Thu, 22 Oct 1998 22:21:00 -0400
> Subject: Water Purifiers
> Let the battle begin!
Ahhhh. Gear wars. Goody.
I personally use a Sweetwater Guardian because it is one of the
least expensive filters that will filter out Giardia and Protozoa.
I have become absolutely paranoid about Giardia and
Cryptosporidium over the last couple of years since protozoan
parasites are spread by animals in their natural environment and,
the spread is unpredictable and apparently unstoppable. What that
means is the fresh bubbling spring in a remote Wilderness Area
cannot be depended upon to be clean these days.
The Sweetwater will pump over a liter per minute with relative
ease. I have tried some other filters, including the PUR hiker
and I thought they were awkward or much harder to pump.
I don't have a "viral" cartridge. Don't think you need to worry
about filtering viruses in the backcountry of the North American
continent (with apologies to the rest of the world where I DON'T
backpack). Now that I've posted this, I'm sure someone on the
list will publish a reference or two which will also make me
paranoid about viruses.
The bad news about filtering viruses is that most water filters"
or "purifiers" don't actually filter out the viruses but, kill
them by passing them through a chlorine, iodine or similarly
impregnated membrane. Some of these chemicals leave a "taste" or
odor in the "filtered" water. Viruses are tiny relative to the
size of bacteria and spores and I would tend to believe that a
filter with pores small enough to filter a virus would be next to
impossible to pump or, would clog after the first couple of
More bad news - all filters clog. There are things you can do to
maximize the amount of water you can process between cleanings.
First, of course, is to avoid disturbing the bottom of the pool or
stream with the inlet hose while you're pumping. The filter will
still clog with suspended particulates - it just takes a little
longer. The most effective way I've found to minimize clogging
and maximize output is to carry along one of those collapsible
nylon buckets ($6.95 on sale at Campmor). Fill the bucket and
carry it back to your campsite. let the water settle out a bit
and pump the water out of the bucket with your filter as you need
it. If you have the luxury of hanging the bucket from a branch or
tree where you can raise the inlet hose higher than the body of
the filter, it's even easier to pump.
Still more bad new - if you store your intake hose with your
outlet hose, giardia spores can still be transmitted to your
"filtered" water supply. In fact, any untreated water, wet hands
for example, can allow Giardia to contaminate your clean water.
Did I mention that I'm paranoid about Giardia?
OK, let's hear about some new water borne plague to worry over.
Advisor Crew 486