View Full Version : Light Reading - Army Water Purification Study
Ok not light (600+ pages), but the most comprehensive study I have seen on portable water purification systems. It is not new (2006), but covers just about every type of filter or treatment on the market at the time.
http://tinyurl.com/3ksjgj8
Rated all of them against 14 different measures using four different user profiles.
The highest rated: MSR SwtWtr Purif.
The lowest rated: H-P SteriPen D
Page 25 of the PDF (16 of the study) has the summary for you all with ADD :)
Anyway, just thought I'd share what I found. I still like my Steripen.
The lowest rated: H-P SteriPen DAdmittedly I just scanned the study, but I'm a little confused that the Steripen has any score at all; figured it would be zero. A Steripen doesn't kill or remove anything, as far as I know; it just eliminates the ability of the pathogens to reproduce. Yet it actually has a score in this study, though a very low one. Does the Steripen actually kill stuff too?
I'll have to read the study more carefully.
Trailbender
07-08-2011, 00:12
I use bleach, the study only said it has somewhat of a problem with crypto.
That is why there is an * next to the Steripen. It did not meet the basic requirements of the study. However, it is in common use in he military so they looked at it. The biggest issue they have with it is it's inability to deal with anything but clear water. Not much on an issue when you get to pick where you get water, but for he Army, their choices at any given moment may not be very good. the "clear" water may only be a quarter mile away, but impossible to get to.
Also, they put less value into "light weight" than most hikers would.
For the most part you don't need to read the whole thing, just the overview score chart and then go to the end to the report for the specific water treatment you are using or considering.
I use bleach, the study only said it has somewhat of a problem with crypto.
There is one more issue to be aware of:
"Ultraviolet rays in sunlight degrade free chlorine compounds in water and significantly decrease disinfection efficacy over time. Chlorine concentrations may be reduced by one-half when exposed to sunlight for only 1 hour (reference 9). To mitigate these effects, chlorinatedderivatives of cyanuric acid, termed isocyanurates, are used to prolong the lifetime of free chlorine in water that is exposed to sunlight. The isocyanurate compound, originally introduced for swimming pool chlorine sanitation in 1960, dissociates in water to form both cyanuric acid, which “stabilizes” free chlorine compounds, and hypochlorous acid, the active disinfectant (reference 9). Chlorine concentrations may be prolonged 3 to 10 times longer in water when cyanuric acid is present in sufficient quantities (reference 9). Studies have shown that cyanuric acid does not interfere with disinfection conditions (reference 10) at concentrations used in drinking water. Some chlorine-using IWPDs may use isocyanurates to prolong chlorine residual in the treated water."
In other words using pool bleach my be better than household bleach. Most people I know that use bleach keep it in a little translucent bottle and don't worry about it sitting on the picnic table for hours. After reading this, I would say keep it in a dark light resistant bottle and keep it in the pack when not being used.
I don't see crypto as a major issue in the mid Atlantic states at least.
ekeverette
07-08-2011, 07:58
damn! i didnt know all that.
Trailbender
07-08-2011, 18:24
There is one more issue to be aware of:
"Ultraviolet rays in sunlight degrade free chlorine compounds in water and significantly decrease disinfection efficacy over time. Chlorine concentrations may be reduced by one-half when exposed to sunlight for only 1 hour (reference 9). To mitigate these effects, chlorinatedderivatives of cyanuric acid, termed isocyanurates, are used to prolong the lifetime of free chlorine in water that is exposed to sunlight. The isocyanurate compound, originally introduced for swimming pool chlorine sanitation in 1960, dissociates in water to form both cyanuric acid, which “stabilizes” free chlorine compounds, and hypochlorous acid, the active disinfectant (reference 9). Chlorine concentrations may be prolonged 3 to 10 times longer in water when cyanuric acid is present in sufficient quantities (reference 9). Studies have shown that cyanuric acid does not interfere with disinfection conditions (reference 10) at concentrations used in drinking water. Some chlorine-using IWPDs may use isocyanurates to prolong chlorine residual in the treated water."
In other words using pool bleach my be better than household bleach. Most people I know that use bleach keep it in a little translucent bottle and don't worry about it sitting on the picnic table for hours. After reading this, I would say keep it in a dark light resistant bottle and keep it in the pack when not being used.
I don't see crypto as a major issue in the mid Atlantic states at least.
I keep it in a transparent dropper bottle, but it stays in my pack until I use it. So I pull it out, use it, and put it back in the pocket. No worries there. I also keep my water out of the sun while it is being treated.
My daughter did her science fair project on this.(Army has a VERY thorough report).
With our local Waterworks help she found the Steripen was the only less than effective method she tested. Colony of bacteria rebounded after 24 hours. So if using Steripen reteat any remaining water atleast daily or drink it faster.
My daughter did her science fair project on this ... the Steripen was the only less than effective method she tested. Colony of bacteria rebounded after 24 hours. So if using Steripen reteat any remaining water atleast daily or drink it faster.I am very proud of my daughter, who is a PhD candidate in biology. If she did an experiment that showed such a result I would believe in her.
I might even publish a note mentioning the results as a data point. Maybe.
Would I state, baldly, "if using Steripen reteat any remaining water atleast daily or drink it faster"? No. Proud as I am, I would need a body of evidence to support such an extreme statement.
You are very, _very_ proud of your daughter. I hope deservedly so, because you have, potentially, caused significant financial damage to a company and its employees if your comment is picked up on searches and widely dispersed among the hiker community.
You and your daughter may have saved some lives.
Fog Horn
07-09-2011, 08:50
I noticed that Aquamira has absolutely no score for the Crypto. It looks like, by the first four categories, the best options are all filters.
Its also amusing to me that even though it scored the lowest, the military uses the SteriPen and even issues it sparingly.
Wil, if a child can do a study of this nature for a science fair project, surly anyone can do it. They sell water testing kits all over the place. He's just sharing a personal antecdote, not causing significant financial damage.
goody5534
07-09-2011, 10:52
Listen, I respect and appreciate all of the men and women who choose to serve in our military but their methodologies are never the "best of" therefore I dont take this study very seriously. There are (2) inhernent flaws with accepting this study as a Gold Standard. First its over 5 yrs old, how many of these products tested have been changed to perform better or worse since then? And, secondly the Army regularly dispenses the Steripen to in-field operatives even though it recieved very low scores... Please explain this logical fallacy... or inherent contradiction...
Trailbender
07-09-2011, 11:42
Listen, I respect and appreciate all of the men and women who choose to serve in our military but their methodologies are never the "best of" therefore I dont take this study very seriously. There are (2) inhernent flaws with accepting this study as a Gold Standard. First its over 5 yrs old, how many of these products tested have been changed to perform better or worse since then? And, secondly the Army regularly dispenses the Steripen to in-field operatives even though it recieved very low scores... Please explain this logical fallacy... or inherent contradiction...
I saw tons of illogical things the Army did when I was in.
Snowleopard
07-09-2011, 12:23
http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA449339
(http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA449339)
I've just read the sections on testing the steripen, because I just bought one. It looks like they tested the 4xAA battery version. The results are not good.
The steripen seems to do poorly in turbid (not clear) water. So, if the water isn't pretty clear, use something else. If the water is clear, maybe it'll work well-- or maybe NOT. The steripen prefilter doesn't seem to help much.
UV works better on giardia and cryptosporidium, so maybe it makes sense to use the steripen in combination with chemicals. Chemicals take hours to kill giardia and crypto but work quickly on bacteria.
Search the document for E-58-1 to find the steripen report.
ANNEX 58 TO APPENDIX E DEVICE EVALUATION #58
HYDRO-PHOTON, INC. – STERIPEN™
...
Although the testing confirms the SteriPEN provides a 6-log bacteria and 4-log virus removal in
clear (low turbidity) water only, it did not confirm the SteriPEN provides similar bacteria and
virus log removals in more challenging (higher turbidity) water.
...
Protozoan cysts (Giardia and Cryptosporidium) on
the other hand are the least resistant, requiring very low UV doses
...
In regards to determining effectiveness against
microbiological pathogens a conservative approach is taken. Based on the manufacturer’s
statement that this device is intended to treat clear water, independent testing challenging the
device in clear water only (and a natural water of unknown turbidity), and the inconclusive effect
of turbidity on UV disinfection, the SteriPEN is not expected to consistently provide adequate
reduction of bacteria, viruses, and cysts even when using the optional prefilter when treating
more turbid waters.
...
There's another set of discouraging steripen tests on page E-58-7:
...Based on this testing, it is not likely that this device will consistently meet the log reduction requirements under any water
conditions. ...
Based on this I'm thinking of returning my steripen.
There's an article on UV disinfection in this report on page F-5-1.
Carl in FL
07-09-2011, 13:14
I doubt the financial damage to a company due to a science fair project
will even approach a fractional value of damage due to the Army report.
There are (2) inhernent flaws with accepting this study as a Gold Standard. First its over 5 yrs old, how many of these products tested have been changed to perform better or worse since then? And, secondly the Army regularly dispenses the Steripen to in-field operatives even though it recieved very low scores... Please explain this logical fallacy... or inherent contradiction...
Well, if you understood that military acquisitions are 90% politically motivated, you would understand the logic behind this.
It's just a study, a pretty good one, but nothing to get worked up about.
In over 35 years of hiking and backpacking, I have never met anyone that got sick from drinking water treated by any commercial water treatment or filter designed for backpackers or hikers. I do know people that got sick not treating their water.
I think it is a good guide to look at when shopping for a new treatment method, but it's just a guide not a gospel.
One thing I didn't quite understand is how they rated disinfectant time. Katadyn micropur purification tablets have a max 4hr time with super cold water. The time is greatly reduced with warmer water. But they used the 4hr max time in all cases. Whereas a filter should have the same very short time regardless of temperature. Seems to me that they would have a bit more meaningful results if they had broken out disinfectants from filters, and then shown disinfectant performance versus water temp. Of course I didn't read all 666 pages to find out if they covered this issue.
I carry katadyn micropur purification tablets because (a) they work and (b) they are lightweight and easy to use. But I don't wait 4hrs for 60*F water - more like 30 minutes. I don't have a problem reloading my water bladder on a hot hike and dumping in some katadyn micropur purification tablets and getting back on the trail - the time hasn't been an issue.