Re: [Paddlewise] water filters was ( Lightweight backpacking stoves)

> If you use one of the Pur, Sweet Water or other
> filters with iodine resin or virus protection it is not an issue. 

And so I've always thought.  The EPA seems to be making a ruckus in
recent years though.  The total history has been difficult for me to
piece together though as the info generally seems to come watered down,
second hand through dealers, and the EPA databases are vague and
non-specific.

I recall many years ago when choosing a filter, being swayed to the PUR
as it was the only one whose display included a hefty binder of included
test results backing up the purifier claims.  You can still find
remnants of that info on site blurbs such as:
http://www.ogo.com/outdoorsman/pur1.htm

More often the dealer info typically contains references to "EPA
REGISTERED AND MEETS (some say exceeds) THE EPA MICROBIOLOGICAL PURIFIER
TEST STANDARD.

But things started to change.  The first I heard of issues a couple
years ago when I was buying replacement filters.  The dealers were
misreporting some issue with the Stop-top accessory.  They said there
was a recall on just the stop-tops.  Some issue with the carbon they
said which could allow bacteria to grow.  They further suggested that I
could keep using my stop-top, but that I should just replace the carbon
from a third party source.

Puzzling, but carbon is so cheap and it was due for replaceing anyway, I
didn't give it further thought.  Seemingly a press with both similar and
different facts vaguely along these lines is reported near the bottom of
this link for the date of June 16 2000:
http://131.104.232.9/fsnet/2000/6-2000/fs-06-17-00-01.txt

Later I noticed fewer dealers stocking the PUR filters, reduced prices,
reduced availability of replacement filters, etc.

And the PUR website stopped mentioning the outdoor filters.

I later discovered Katadyn had scooped up the PUR line.
And Sweetwater had also had pulled their purifier equivalent from their
line, and a browse to the purifier section under the PUR banner gives
only:
http://www.katadyn.com/outdoor/pur/our_products/Purifiers.asp

And their FAQ gives a note to the change of hands, and more info on the
issue:
http://www.katadyn.com/outdoor/pur/faq/default.asp#available

Further, dealers, in addition to "out-of-stock" notices started adding
blurbs such as, "IMPORTANT NOTICE:

All PUR portable units EXCEPT THE HIKER are experiencing a delay due to
reevaluation of the carbon StopTop. The StopTop, sold with all the
purifiers below, was revealed to interfere with the main purifier's
ability to fully eliminate viruses in outdoor (untreated) water.
Normally it acts as a water bottle adapter and reduces the water's
iodine content from treated water for improved taste. This issue does
not affect the ability to remove cysts or bacteria.

If you already own a PUR, you can still use it. It is advised to remove
the StopTop and follow use directions for "How to Handle Difficult or
Extreme Water Conditions" located in the use and care manual."

You also see a bit of mis-information in Q&A's like this:
http://web.outsideonline.com/gear/gearguy/200106/20010629.html

Obviously the EPA *used* to believe they worked just fine.  We have
reams of test data.  And the filters have been registered with the EPA
as level 1 purifiers for years.  So what happened?

There and notices from the EPA in 2000 about new water quality rules,
the EPA taking a world wide leadership role... etc, etc.  I won't
contrive to connect dots, but it would seem there's some redifining
going on, perhaps in response to bad press over water issues in the news
that have been horrifying people on both sides of the media reports.

Essentially it seems to boil down (sorry for the pun) to the following. 
The theory was always that water was filtered down to 0.3 microns for
the purposes of cysts, and most bacteria.  By happy happen-stance most
viruses are glommed onto larger molecular groups such that you end up
shedding most of those with the filtration as well.  For everything
smaller, there's the iodine resin layer to kill what remains.  Then it's
on to the carbon stage to remove pestisides, chemicals, "flavors", etc. 
Iodine is quite useful as an anti-viral stage in quite small levels, but
it also affects taste.  Moreover while it's fine to consume over short
periods, the added benefit of the carbon layer was to remove a good
portion of the iodine at the end of the filteration cycle because the
other issue is that continuous increased iodine levels over multiple
months (if one was using the filter on a long excursion) is not great
for such organs as the thyriod etc.  Hence the other benefit of limiting
iodine level in the final stage.

The temporary recomendations were to:
 
"In the meantime, consumers who already own PUR camping purifiers can
still use them. In order to ensure full anti-virus efficacy, we advise
you to remove the StopTop and follow use instructions for "How To Handle
Difficult or Extreme Water Conditions" located in your Use and Care
Manual. Briefly, the process involves the following four steps:

1. Disconnect the StopTop carbon filter and pump water into a temporary
container at a rate of less than 10 strokes per minute.
2. Remove the inlet hose from the water source and pump the purifier
until air comes out of the output hose.
3. Place the inlet hose into the temporary container and pump water into
your water bottle or canteen at a rate of less than 10 strokes/minute.
4. Let the water stand for 20-minutes before consumption."


Doesn't sound like any "irregular" batches of carbon, rather it sounds
as though you're simply iodine loading the water and letting it stand to
accomplish the AV work (and living with all the stuff in the water that
the carbon would have removed).

Seems they also forgot about the carbon accessory the screws onto the
bottom of the device between the filter and the hoses (which I have
installed for a double carbon scrub).  There's been no mention of that,
and removing it as well.

I guess I would have thought it much less hassle to collect your water,
treat it with liquid iodine for the required time, then filter it with
the PUR (carbon layers in place).  But it's a little tough to know when
you're left without details.

And after all that you're left wondering if these hoops all because the
EPA is after that last 0.001%.  Or what the deal is.  All I know, is
I've been sick from unfiltered water, and never again since using my PUR
(well, that is unless I look back at the unfiltered source of the water
I just consumed, but that's just a mental thing ;-)

When all else fails, there's still one name in the purifier market
happily gloating:

http://www.generalecology.com/EPA%20Microbiological%20Std.html

And the hope for the mythical new purifier replacement filter from
Katadyn for current PUR filters.  But it's been a year and a half since
they took over...







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