Water Filters

Here is a website about filtering methods-evaluations.

http://chppm-www.apgea.army.mil/wpd/CompareDevices.aspx


kind of interesting (in it's own right).

Thanks for the info. Just to let you know: the link you posted has an extra period at the end. You may want to edit it.

Corrected link...

Hmmm...says that iodine treatment not effective agains Giardia or Crypto...so why am I carrying it again? MicroPut tablets would be good...but who wants to wait 4 hours for a drink. So I guess my Katadyn Hiker will do or I will boil it.

I just can't believe that the iodine is not effective against Giardia or Crypto...so why does the military still use that method?

Giardia & Cryptosporidium are clearly a problem for those treating water.

Most water filters will screen out bacteria (think e. coli), but won't screen out viruses and the G & S cysts.

Iodine and regular chlorine bleach will kill bateria and viruses, won't destroy the G & S cysts.

Chorine dioxide (and its relatives ala Miox) will destroy bateria & viruses in 15 minutes, but can take four hours to destroy the Giardia & Cryptosporidum cysts. If you read Doug's section on water purification you'll see that 30 minutes of treatment is likely sufficient, unless you're dealing with near-frozen sewage.

Of course the downside with chemical treatments is that they work best if the "big chunks" of organic debris are removed (using a bandanna is better than nothing), and even then they won't remove the dead oraganic bits after treatment (just think of it as nutrient-rich soup).

From what I can find on the web, it sounds like the likelihood of being exposed to G & C in wild areas is actually pretty remote, mostly due to dilution of the source (it typically takes more than just one cyst to get you sick). The chance of viruses sounds like it is very small too. From what I can tell the biggest risk is bacteria, which is removed by most filters and chemical treatments.

I suspect the Army is mostly focusing on viruses and bacteria. I know that the Boy Scout policy is to treat with chlorine bleach, which means that they are also focusing on viruses and bacteria. If you think about it, ALL public pools and hot tubs (and most private ones) only treat with chlorine - again the focus on viruses and bacteria.


My plan:

For my family of four, I have several collapsible 1-liter Platypus bags and a Miox in the car kit. With extra batteries (tiny and VERY light weight) and a small amount of kosher salt, the Miox can treat something like 400 gallons of water. Given I carry a PLB in my car kit too, that should cover us just fine.

When out with the Scouts, I have a few Micropur tablets slipped into my Ritter PSP, and carry that in my personal kit, and I carry a 1-litter Nalgene bottle.

Ken

Gairdia and Cryptosporidium are larger than 2 micron and thus CAN be filtered out by many filters.
Some iodine resine based purifiers will have questionable results on Gairdia and Cryptosporidium, when they don't have a 2 micron or smaller filer medium. (like granulate based iodineresin/carbon filters/purifiers)

This is also discussed on another site Make water safe to drink in this opinion boiling is really the only method that is surefire.

The AF has gone to Micropur

I've been looking for a filter for a couple of months, recently I found this one. Sawyer Water Purifier. It is supposed to physically remove viruses with out the aid of chemicals. The best I can tell, Sawyer released this sometime around the middle of 2006. So it's pretty new to the market. I've posted questions about this purifier on other sites but have yet to find anybody that has any experience with it.

Below is an article I found about the Sawyer Purifier.
Just Drink(TM) Water Purifier Essential For Hurricane Preparedness

So far the best price I've found is from Moontrail.com
$79.00 for a bottle, purifier, and faucet adapter.

smitty

The modular design is interesting, it appears to be an inline immersable filter that can connect through a tube to a bottle, bladder, or faucet.

It may be a good choice if it is mainly being used as a gravity filter or with a faucet, but I think the lack of a pump is a disadvantage. In my experience, using a bottle type filter causes you to drink less water, due to the effort it takes to squeeze water through. With this system you can't quickly fill a number of containers with water, unless you have access to a working faucet with sufficient pressure.

I personally think a reliable, field-cleanable, pump type filter, such as the MSR waterworks or the time tested katadyne pocket, is more versatile and useful for many situations.

ANYONE know the pore size of coffee filters??
i ask because i have an older model PUR filter--the Ultralight,
and i'm just about out of the paper filter discs and a web
search has come up blank..

The Ultralight is a great filter for mountain dayhikes, where Giardia is the main worry. It has saved me from lugging excess water for many a weary mile.

There's no way a coffee filter would work as a replacement, though many use it as a silt filter to extend the life of the main element.

I'll keep my eyes open for replacements. I hope they're still available.

The Web always has your answer:
http://geo.uri.edu/skydust/faqs.aspx and search the page for pore.

(Executive summary: Coffee filter pore sizes average about 100 microns.)

100 microns!! well it seemed like a good idea at the time-