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Pristine

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  • Justin E. Vlietstra
    I found a decent document from the epa describing chlorine dioxide at http://www.epa.gov/ogwdw000/mdbp/pdf/alter/chapt_4.pdf I trust EPA reports more than
    Message 1 of 5 , Apr 3, 2001
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      I found a decent document from the epa describing chlorine dioxide at
      http://www.epa.gov/ogwdw000/mdbp/pdf/alter/chapt_4.pdf

      I trust EPA reports more than manufacturers claims. The document has a lot
      of info. The first third is not of interest but the rest of it has a lot of
      useful info. In particular it has graphs of the effectiveness of chlorine
      dioxide against viruses, bacteria, giardia, and crypto.

      I am having some difficulty interpreting the information, particularly the
      graphs. The graphs have log on one axis and CT on the other. Log1=90%
      killed, log2=99%, log3=99.9%, etc. CT is supposed to be the product of the
      residual chlorine dioxide concentration (mg/L) and the contact time
      (minutes). What I don't know is the concentration of chlorine dioxide in a
      pristine treated liter of water. I had a number of 50ppm floating in my
      head for some reason but I don't know what that is in units of mg/L.

      Anyway, the document does say that chlorine dioxide kills viruses, bacteria,
      and giardia. It is less effective against crypto, particularly in cool
      acidic water for the contact times hikers will tolerate. It looks like
      chlorine dioxide concentrations high enough to kill crypto within a short
      time would be unhealthy. Chlorine dioxide does produce some potentially
      harmful byproducts so its maximum concentration is limited by the EPA to
      about 1.5mg/L. The document also mentions that chlorine dioxide does
      adversely affect the taste of water in concentration above 0.5mg/L.

      My interpretation of the information in the document is that chlorine
      dioxide is sufficiently effective for the types of water we are likely to
      encounter. It probably won't kill 99.99% of everything, but it should kill
      enough that our immune systems can easily handle whatever is left. So my
      guess is that it is effective but not sufficiently so to pass the EPA's
      tough criteria for water purification.
    • Ryan Jordan
      ... Excellent find, Justin. This is a peer-reviewed document that should be considered as reliable as anything. ... I think someone should contact the
      Message 2 of 5 , Apr 3, 2001
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        > I found a decent document from the epa describing chlorine dioxide at
        > http://www.epa.gov/ogwdw000/mdbp/pdf/alter/chapt_4.pdf

        Excellent find, Justin. This is a peer-reviewed document that should be
        considered as reliable as anything.

        > What I don't know is the concentration of chlorine dioxide in a
        > pristine treated liter of water.

        I think someone should contact the manufacturer and find this out. It would
        be very useful information.

        > Anyway, the document does say that chlorine dioxide kills viruses,
        bacteria,
        > and giardia. It is less effective against crypto, particularly in cool
        > acidic water for the contact times hikers will tolerate.

        I found this to be interesting. Even at a contact time of 60 minutes for a
        neutral or acidic water source (like a forest stream) you may be looking at
        a 60 ppm (mg/L) or greater dose to generate a 2-log reduction in Crypto...

        I think the real benefit of this chemical lies in its ability to knock out
        bacteria, and to some extent, viruses. Thus, combine it with a sediment
        prefilter (eg, coffee filter) and a high-flow microfilter (eg SWA) to remove
        cysts and you should have a pretty bombproof little backcountry water
        treatment plant.

        > Chlorine dioxide does produce some potentially
        > harmful byproducts so its maximum concentration is limited by the EPA to
        > about 1.5mg/L.

        Keep in mind that this is for ingesting it day after day after day after
        day...I don't mind a higher conc on occasion as long is it isn't
        overpowering.

        Also, you could pretreat with a high chlorine dioxide dose then zip the
        water through an SWA to nab up any remaining nasties. The carbon core of the
        SWA should remove taste associated with the chlorine dioxide.

        > My interpretation of the information in the document is that chlorine
        > dioxide is sufficiently effective for the types of water we are likely to
        > encounter. It probably won't kill 99.99% of everything, but it should
        kill
        > enough that our immune systems can easily handle whatever is left.

        That's my philosophy as well.

        > So my
        > guess is that it is effective but not sufficiently so to pass the EPA's
        > tough criteria for water purification.

        It actually has been endorsed by EPA as a viable water purification
        technology. The main problems in implementing it is that it must be produced
        onsite (can't be shipped in high concentrations, too explosive) and
        production results in some terrible byproducts (perchlorate/perchloric acid
        I think, but I can't recall right now). So, implementing it is expensive and
        is not necessarily a function of lack of EPA blessing.
      • GearTester
        Thanks, Ryan. That answered some questions I had...and reassured me that the system I use, about the same except for the Seychelle filter and Pristine, should
        Message 3 of 5 , Apr 3, 2001
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          Thanks, Ryan. That answered some questions I had...and reassured me that the system I use, about the same except for the Seychelle filter and Pristine, should do the trick. And thanks to Justin for the original article.
          Jerry
          ----- Original Message -----
          Sent: Tuesday, April 03, 2001 1:56 PM
          Subject: Re: [BackpackGearTest] Pristine

          Excellent find, Justin. This is a peer-reviewed document that should be
          considered as reliable as anything.

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