Re: [Philmont]: Water Treatment

Thanks, Neal. This is the best summary I have seen.

Dan Preston
Louisville, KY
On Mar 21, 2006, at 2:25 PM, Neal Osborn wrote:

> Hi all,
>
> This topic has started to stray just a bit from my original questions,
> but that's ok.  I thought I would present some information.  I am not
> a credentialed expert in water treatment, but I have a high degree of
> confidence in the statements to follow.
>
> Treating back country water for human consumption involves getting rid
> of three general categories of contamination:  suspended solids (muck,
> dirt, sand, etc.), chemicals (petroleum, pesticides, heavy metals
> (Arsenic, mine tailings) and the like, and biological agents
> (bacterial, viruses, cysts).
>
> Boiling ("the most certain treatment" - Philmont Guidebook to
> Adventure) will kill all biological agents.  The technique is to get
> the water to a rolling boil.  The combination of heat and time
> required to get to that point is sufficient.  Boiling does not remove
> suspended material nor does it remove chemicals.
>
> There is an important distinction between "filters" and "purifiers."
>
> Filters generally will remove suspended material, many chemicals and
> most will get most bacteria.  Filters force solution through very fine
> holes (pores), eliminating stuff that's bigger than the holes.  The
> most popular portable filters sold today have pore sizes of 0.1 to 4
> microns.
>
> The Giardia cyst (a common intestinal parasite) is 6 microns in
> diameter and many bacteria are larger than 0.2 microns. Small pore
> filters (at least 0.2 microns) can remove such organisms. Viruses,
> however, range from 0.004 to 0.06 microns in size -- far smaller than
> the pore size of the best portable filter.
>
> Note that while cysts are among the easiest biological agents to
> filter, they are among the hardest to kill via non-mechanical methods
> (heat, chemicals).
>
> Purifiers must be certified by the EPA for sale in the US.  The EPA is
> involved because most methods of purification involve chemicals. 
> Purifiers remove biological agents, and usually filter as well.
>
> There are a number of purifier devices on the market.  Most use a
> chemical treatment to kill biological agents, frequently in
> combination with a filter.  For example, the "MSR Sweet water Purifier
> System" adds a "purifier solution" to the water after it has been
> filtered by the machine.  The PUR Hiker includes an "iodine matrix" in
> the filter mechanism.
>
> The MSR MIOX converts a brine solution to a mixed-oxidant solution via
> electrolysis.  Note that this product generally lacks filtration.
>
> Polar Pure (Philmont's old method) will kill all biological agents. 
> Under some conditions it may take several hours.  Does not remove
> suspended material nor does it remove chemicals.  Leaves an iodine
> taste, which some find objectionable. 
> http://www.polarequipment.com/page2.html
>
> Micropur (MP1) was developed as a second step after filtration to
> eliminate remaining biological agents.  As with Polar Pure, it will
> kill all biological agents, given proper concentrations and enough
> time.  Based on chlorine (like most municipal water systems), there is
> generally no aftertaste.  Does not remove suspended material nor does
> it remove chemicals. 
> http://www.katadyn.ch/site/us/home/outdoor_products/our_products/
> ultrlight_series/micropur_mp1_tablets/
>
> There is at least one purifier that employs a non-chemical method to
> eliminate all biological agents, the First Need product. 
> http://www.generalecology.com/portablesystem.htm
>
> So, boiling, Polar Pure and Micropur MP1 will kill biological agents,
> but do not remove suspended material  or chemicals.
>
> Filters remove suspended material and chemicals, and most biological
> agents, but not all.
>
> Purifiers remove biological agents, and most also remove suspended
> material and chemicals, depending on the associated filtering system.
>
> Perhaps the biggest difference between filters and purifiers is
> removing viruses (filters no, purifiers yes).  There is an on-going
> debate about the prevalence of viruses in back country water sources,
> and thus the need for "purification."  Most viruses are
> species-specific, and a lack of human activity in the "back country"
> would argue that there is little need for virus purification. 
>
> I think the heavy human use of Philmont would argue against that
> proposition, and in favor of treating for viruses.
>
> Neal Osborn
> SCCC 2006
>

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Received on Thu Mar 23 15:30:59 2006