Ultralight (17g) 1-Micron Water Filter

Ultralight (17g) 1 Micron Water Filter

Water filtration systems can be bulky and heavy. Depending on the type that you choose they can also be expensive. Pumps and mechanical devices are prone to blockages or failures and chemicals alone result in a less than desirable end product. So what should you do?

I’ve grown more and more dissatisfied with many of the water filtration solution options on the market. The ones I’ve tried have worked to a degree but have been either too heavy, too needy, or too slow to be viable as truly lightweight options. So after a lot of thought and online research into materials I decided to have a go at making my own filtration system.

Gravity Water Filter

For over a year I have been using the Aquamira Frontier Pro gravity water filter system that was first written about by Jason Klass. It has been a great lightweight system for the most part, but I have had terrible issues with the flow rates of the Frontier Pro filters themselves. Some of them flowed extremely well, while others seem to hardly flow at all, more like a slow drip. Finding out that you have a brand new ‘dripping’ filter in the field can be a royal pain. I’ve even had one or two of these filters that completely refuse to flow at all. Aquamira have commented that they were aware of this issue and have improved their product design and quality controls, but I’m not willing to stick with it as my primary filter after the experiences I have had.

Some of my trail friends carry just purification tablets and swear that they have no issues with them. Technically that may be accurate, used right purification tablets can deal with most of the nasties in water, but I can’t face the thought of all the crud floating around in my unfiltered water. That’s one of the reasons why the SteriPen trend is definitely not for me.

After thinking about all of the different solutions I have tried over the years, some good, some not so good, I came up with the following basic requirements for my own lightweight water filtration system:

  • No moving parts to fail
  • Replaceable filter/pre-filter
  • At least 2 microns
  • Inexpensive
  • Lightweight
  • Pack small
  • Good flow rate

During my online research into water filtration options I came across a very interesting video by djbarryiii on YouTube showing how he had made a simple filter using a bio-diesel oil filtration sack bought on Ebay. It’s a great video and definitely worth a look, I also have to credit this video as the original concept that sparked off my own quest for a light weight filtering solution.

My backpacking buddy Mr. Andy and I ordered a multi-pack of large bio-diesel filter bags with a 1-micron absolute rating from Ebay at a total cost of around $15. These would serve as the primary filtering material for my filtration system. For the purpose of comparison, an Aquamira Frontier Pro is rated to remove 99.9% of Cryptosporidium, Giardia and other contaminants down to 3 microns. The Aquamira Frontier Straw is rated to be 99.9% effective against waterborne pathogens and contaminants as small as 2 microns.

Filtration Material Terms:
The pore size of filter media is identified by the diameter of the particle that it can be expected to retain with a defined, high degree of efficiency. Pore sizes are usually stated in micrometer or microns for short (µm), which equals one millionth of a meter. Pore size ratings refer to the size of a specific particle or organism retained by the filter media to a specific degree of efficiency. Ratings can be stated as either nominal or absolute pore size.

An absolute pore size rating specifies the pore size at which a challenge organism of a particular size will be retained with 100% efficiency under strictly defined test conditions. Among the conditions that must be specified are: test organism (or particle size), challenge pressure, concentration and detection method used to identify the contaminant. E.g. live bacteria test. Absolute micro-filters are used for critical applications such as sterilizing and final filtration.

A nominal pore size rating describes the ability of the filter media to retain the majority of particulate at (60% – 98%) the rated pore size. Process conditions such as operating pressure, concentration of contaminant, etc., have a significant effect on the retention efficiency of the filters.

Components
I liked the combination of pre-filter, filter, holder, and water container that Barry had shown in his video, but I had some ideas of my own on how I wanted to make a collapsable holder and make use of my existing water bladders as the containers instead of the yogurt carton shown in the video. Below is a concept sketch that I drew on the whiteboard in my office of what I was thinking.

Water Filter Concept Whiteboard

As you can see from my concept sketch, I wanted to create a cone-shaped funnel that could store flat or be rolled up with my bladders inside my backpack when not in use. I also wanted the cone holder to be quick and easy to assemble when needed. I made several paper mock-ups to make sure that the final shape fitted into the mouth opening of my Platypus and Evernew bladders and also to test out the locking tab feature that would hold the cone in place. As it turned out, getting the size was relatively easy, but tweaking the locking tab took 4-5 attempts to get just right.

Ultralight (17g) 1 Micron Water Filter

To make the cone holder I used an old disposable cutting mat that we were about to throw into the recycle bin. You can buy these cutting mats in packs of two or three at most grocery stores or big lot stores for just a few dollars – they are pretty inexpensive. This one had served its time well and was ready to move on to a loftier purpose.

Using the paper template that I had tweaked, I cut out the cone shape from the plastic cutting mat. Based on the size of the template I had created I could easily make 5-6 of these folding plastic cone holders out of the one cutting mat. I had to use a craft knife (scalpel) to make the slit where the tab of the cone slots into place. I had to lengthen the slit slightly more than m paper mockups in order for the tab to fit properly, probably just because the plastic was less flexible than paper.

Ultralight (17g) 1 Micron Water Filter

Using the larger diameter of the cone pattern as a guide, I cut out a circular piece of filter material. By pure luck I found that the plastic lid to my coffee bean container was almost perfectly the right size (6 inches in diameter) so I used that as a guide to draw my circle. As I mentioned earlier, the filter bags that we bought via Ebay were large and I estimate that I could cut out at least six filters from each bag, maybe even more if I was more careful about squeezing them together. Considering each bio-diesel filter bag cost roughly $2 a piece, that means each of my circular filters cost approximately 33c.

Ultralight (17g) 1 Micron Water Filter

With Barry’s video as a guide, I folded my filter material in half and then in half again to create a quarter circle. I glued the two straight edges together on the outer edge using crazy glue and a clamp. By folding it and glueing the edges it creates a cone shape that has two pockets that can be used for filtering. Most importantly, both of the pockets do NOT have any holes at the bottom, so it guarantees that all of the water being poured into it has to pass through the 1-micron filter material.

To help preserve the longevity of the 1-micron filter material, I added a standard coffee filter to the inside of the main filter to act as a pre-filter. This will catch the majority of the crud in the dirty water and help prevent the main filter material from getting clogged up too quickly. Coffee filters are also very cheap and easy to replace. I figure I can get a few days worth of use per coffee pre-filer and carry 2-3 as part of my kit. When a pre-filter is used up I can dry it out and use it as tinder.

Ultralight (17g) 1 Micron Water Filter

The coffee filters I had (the large corrugated ones) needed to be cut down to size so that they fit nicely inside of the pocket created by the filter material. Again I used the lid of the coffee bean can as a guide for how big to cut it.

Assembling the pieces of the fitter system is very easy, there are just three parts; the plastic cone holder, the main filter material, and the coffee pre-filter. There is only one thing to be careful of which is that you are using one of the two pockets created by the folded filter material and NOT using the middle section which has a huge hole/gap in it and won’t filter the dirty water properly. The combined weight of all three components is a mere 17g!

  • Coffee pre-filter: 0g
  • Main 1-micron filter: 11g
  • Plastic cone holder: 6g

My original intention was to make the plastic cone holder so that it would fit into the narrow neck of my Platypus and Evernew water bladders. After assembling the components and checking the fit I was pleased to see that it sat perfectly inside the neck of my bladders.

Testing the System
Unlike my previous gravity water filter system that could be left to hang and slowly filter the dirty water, I needed this to have a much more responsive flow rate because I would have to hold it the entire time I filtered the water. I definitely wanted to test the new system at home before taking it out on the trail.

Ultralight (17g) 1 Micron Water Filter

I started with two cups of water and poured it through the combined setup. To my surprise very little water came out through the bottom of the filter. I was bummed and thought I had messed up somewhere, not that there were an lot of steps to really screw up. Then my son Jack came to the rescue with a brilliant observation. “Dad, most of the water was soaked up by your filter.” Doh, he was right. The next few cups of water that I poured through the filter had an almost perfect flow rate, slowed down just fraction by passing through the two layers of filtration material. The flow rate was amazing after getting the filters wet. My guess is that over time as both the pre-filter and main filter become clogged up, the flow rate will inevitably slow down, but for now it’s excellent and I can easily swap out the coffee pre-filters.

To be safe I still plan on using Micropur water purification tablets to treat the water either before or after it has been filtered. It may or may not be necessary, but why take the chance? I’ve found that there is minimal bad taste from Micropur tablets, so it doesn’t bother me to add them. I’d prefer not to have to wait for them to work, but time and patience is one of the benefits of being out doors and having plenty of time to relax.

I’ll be testing this new filtration system a lot more in the coming weeks to make sure it is reliable and durable enough to carry with me on a trip. Unfortunately the only real way I have of testing the effectiveness is through trial and error using myself as a guinea pig. Hopefully I won’t be getting sick from contaminated water in the coming weeks.

What do you think of my new water filtration system? Please leave a comment below.

Be Sociable, Share!
  • http://pig-monkey.com Pig Monkey

    Pretty neat! I’m usually a chlorine dioxide only guy, but this is simple enough that I might have to add it in.

  • Jolly Green Giant

    I was waiting to see what you came up with.  Well done, you have my attention.  I’ve used the same kind of painting filters before with limited success, but didn’t have the same overall robustness of the system as you did.  I’ll need to try your way.

  • James Conley

    I’m currently using Chlorine dioxide and the steripen fitsall filter. I’m also carrying a small cup to scoop water with to pour it into the filter.

    Your system of paper filters though is going to absorb the water into the filter and then you’re going to pack out the wet filter. Coffee filters as a prefilter is a nifty idea but since they are so thin you’re only going to get one use out of it so you’ll need to carry several of them in a water proof ziplock bag separate from everything else. The wet 1-micron filter will need to be in another ziplock bag along with your plastic cut-out and whatever dirty-water scoop / cup that you use. I love the idea though of a cheap DIY filter. I’m just wondering what you could use that wouldn’t suck up the water and hold it like cloth and paper filters tend to do.

    • JJ_Mathes

      I use the toe end of a nylon stocking as a pre-filter and AquaMira drops. Water is easily squeezed out of the stocking and it’s fast drying, I used one last year for over 600-miles and who knows how many gallons of water. It’s not as fine toothed as a coffee filter, but certainly durable. I’ve never used a second stage filter like Brian shows with the biodiesel filter. I realize my method may not filter out as much, but after using it for over 2,000 miles I’ve experiences no problems. 

    • http://www.briangreen.net Brian Green

      James, you raise some very interesting points. My initial weight of 17g is “dry” and will be significantly different when wet. I disagree on having to change the coffee filter for each use, I’ve been using the same one for 3-4 filters of dirty (stream) water and it holds up fine, but 4 is about the max.

      I had planned on rolling all of the components up inside my platypus bladder and securing with a shock cord, but I see where you are coming from with regards to dirty contamination. I’ll have to think it through to have the least amount of baggies.

      Great feedback thank you. It’s still a work in progress, so I’ll see how it goes.

  • Peter

    I think you’d get a higher flow rate if you add a layer of highly porous material between the filter and the plastic cone. Otherwise, the flow will be concentrated at the tip of the filter. An eighth of an inch of open-cell foam would probably help a lot. Or maybe another coffee filter, crumpled or pleated to provide open spaces. Just make sure to get something food-safe that won’t promote bacteria or algae growth. And for that matter, are you sure that bio-diesel filter material is safe?

  • Pete J M

     I would caution that this filter may not be so safe alone?  With Chlorine Dioxide etc, the bacteria, virus and other organisms are killed, so NP.  But with just filtering, the coffee filter, and the 1 micron filter will be full of live bacteria and organisms…  That might end up on the “clean” side while the wet filters are stored in your pack; as a few drops of water go from dirty to clean side, or to the plastic bag they are in.   
     Know you are using Micropur (Another brand of Chlorine Dioxide) so you will be ok.   You’re just removing some dust, dirt and dead organsms with the filter(s)…  Mostly for taste / personal comfoft.  Probably does not make the water any safer to drink?  
     Also I think everyone knows that even though a 1 micron should be 100% good at removing bacteria, it will not filter many types of virus types.

    • http://www.briangreen.net Brian Green

      Pete, I totally hear what you are saying, but if a 1-micron filter is not safe to use, how do commerical filters like the Aquamira Pro (rated down to 3
      microns) and Aquamira Frontier Straw (rated down to 2 microns) claim to be safe on their own without the use of a chemical second stage?

      The data on what is safe and what is not safe seems to be shrouded in mystery and/or inconsistent information. Fortunately I always use Chlorine Dioxide tablets, but would have hoped that 1-micron alone would have been sufficient.

      • RickC

        It seems to me that the Chlorine Dioxide tablets, the pre-filter and the funnel are all you really need. Then its wicked light, safe and crudless.

      • Pete J M

        This is a quote from Aquamira site about their straw:
        ”  Although the Frontier Filter does reduce bacteria and virus, it is not certified to remove >99.9999% of bacteria and >99.99% of virus required by the US EPA water purifier standard.  For maximum protection, use in conjunction with Aquamira Water Treatment Drops or Aquamira Water Purifier Tablets.”

        No normal filter that I know of removes virus to US EPA standards…  SOME filters do have chemical treatment layer to take care of this…  There are some squeeze bottles with such filters… 

        An ultrafiltration membrane will remove virus, but needs lots of pressure to get any flow because openings are small ebough for only H2O molecules to pass through…   Though there is an ultrafiltration system that uses osmotic pressure… You put a electrolyte (something like powdered gatorade) on the clean side…  The higher salt concentration that dirty water (or yes, even urine) will drive the clean pure water through the ultrafiltration membrane.   Last time I looked.  Those were too expensive for normal use.  Think military may use them…  (Snipers who can’t move for days, etc…) 

        My concern with your setup (without chemical treatment), is that the dirty side of both the pre-filter and the 1 micron filter will likely contaminate the clean side when you store in a bag, especially if wet.  Water will run from one side to the other…   In commercial filters, this type of contamination of the clean side doesn’t happen unless the filter leaks or breaks. The contaminated side and cleean side are separated.

        The reason most people are OK with 1-2 micron commercial filters alone, is that most sickness in the wild is caused by bacteria, and organisms… And less likely from virus..  So no problem if no bad virus in the water to begin with… 
        Anyway, that’s how I understand it… 

        For me chemical treatment is lighter and guaranteed safe.

  • Rknuteson

    Sorry, but I use Aqua Mira and have for years. Simple, light, and pretty much fool-proof.

  • http://twitter.com/glenvp Glen Van Peski

    I’ve used chlorine dioxide only for many years now with no problems.  This definitely caught my eye, though.

    • http://www.briangreen.net Brian Green

      Glen, I thought you used a small piece of pre-filter material? Is that no longer the case or am I mistaken? Thought I saw that on your “What’s in my pack” video.

  • Billy Matkovich

    This seems like it would be a perfect UL pre-filter to combine with a SteriPen! Actually, I like your fold-flat funnel and coffee filter as a pre-filter. It seems better than our bandana-over-the-nalgene method.

  • http://www.facebook.com/bradawayattewaye Brad Attaway

    My comment copied from a thread on Backpacking Light:

    I haven’t tried it yet, but I’m nearly certain it will work and only add a few grams to what I usually bring:Cut a small corner off a plastic freezer bag (could use smaller, but then it would be less effective at scooping water to be filtered.Into the cut off corner of that freezer bag I intend to wad my mosquito headnet and/or the camp towel I bring in place of a bandana (why do so many people insist on a cotton bandana when a lighter, more absorbent square of technical fabric is available?)for two stages of filtration (headnet for the big floaties and camp towel for whatever makes it through the headnet).  The wadding should give that corner a funnel shape.grip the makeshift filter material from outside the bag to hold it in place, and use the other hand to hold the top of the bag open in a scoop shape.Scoop water from wherever, let said water drain through the filter cornerinto its final container (holding this corner up top while scooping also reduces cross contamination with the portion dipped in dirty water), and treat the now theoretically much cleaner water as preferred (My Steripen is my guilty 3 oz).Whether you bring a headnet/bandana/towel or not, There’s probably something you could wad into the corner of a plastic bag to make an effective pre-filter at only the added weight of the plastic bag.

    • http://www.briangreen.net Brian Green

      Brad, thanks for sharing. I’m pretty confident that your method would work fine, as long as your treatment of the “filtered” water is thorough. The pre-filtering that we are both doing via our different techniques is really just to get out the big nasties – proper water treatment is still necessary to be absolutely safe.

  • http://www.facebook.com/bradawayattewaye Brad Attaway

    My comment copied from a thread on Backpacking Light:

    I haven’t tried it yet, but I’m nearly certain it will work and only add a few grams to what I usually bring:Cut a small corner off a plastic freezer bag (could use smaller, but then it would be less effective at scooping water to be filtered.Into the cut off corner of that freezer bag I intend to wad my mosquito headnet and/or the camp towel I bring in place of a bandana (why do so many people insist on a cotton bandana when a lighter, more absorbent square of technical fabric is available?)for two stages of filtration (headnet for the big floaties and camp towel for whatever makes it through the headnet).  The wadding should give that corner a funnel shape.grip the makeshift filter material from outside the bag to hold it in place, and use the other hand to hold the top of the bag open in a scoop shape.Scoop water from wherever, let said water drain through the filter cornerinto its final container (holding this corner up top while scooping also reduces cross contamination with the portion dipped in dirty water), and treat the now theoretically much cleaner water as preferred (My Steripen is my guilty 3 oz).Whether you bring a headnet/bandana/towel or not, There’s probably something you could wad into the corner of a plastic bag to make an effective pre-filter at only the added weight of the plastic bag.

  • http://www.briangreen.net/ Brian Green

    Brad, thanks for sharing. I’m pretty confident that your method would work fine, as long as your treatment of the “filtered” water is thorough. The pre-filtering that we are both doing via our different techniques is really just to get out the big nasties – proper water treatment is still necessary to be absolutely safe.

  • http://www.facebook.com/people/Steve-Lowe/1217265585 Steve Lowe

    I am new to the ultra-light packing world and was looking for a lighter way to procure water. I have an idea on something but now, having read all the comments here, I am second guessing it. I plan on using a Aquamira Frontier straw to filter my water and it filters down to 2 microns… Is that enough?

    If not, what about the 4 drops of bleach to go along with it.

    What grows at 1 micron or smaller that would be missed by this filter here in the thread or my frontier straw? I am looking to avoid taking my 14oz MSR Sweetwater filter and taking my Aquamira setup that weighs in at 2 5/8oz. My MSR is not rated to filter viruses and for two years with that filter I have had no issues. I do, however obtain water from fast moving streams. In only one area was the water source but a puddle. It was a dried up stream that had a trickle from the spring. This trickle was opening into a puddle and were many of us collecting water. Eather way, the MSR worked great. The puddle was dirty so the MSR clogged, but neither of the three of us in my group got sick.

    It is my understanding that we aren’t to worry about viruses. Are the viruses the nasty little critters that are smaller than the 2 or the 1 microns?

    • Jenny C

      This is my understanding too. All of the water filters available to wilderness backpackers are intended to be used in the field without the addition of chemicals quite simply because the risk of virus ingestion is so minimal.

      Now if you were going to be backpacking through a populated area, your need to be concerned about viruses in open water would be appropriate- and chemical treatment necessary.

      I think this system would be just as effective as any other water FILTERING product (as long as the filter was not contaminated clean to dirty side in storage).

      If you are concerned about protecting yourself from water-born viruses though, you need to take into account more than just the water you are ingesting. Viruses enter the body through any bodily fluid (saliva, sweat, nasal mucus, blood, semen, vaginal secretions) so after touching the water source, you would need to sanitize your hands and you would need to use chemically treated water in contact with any part of your body.
      Honestly though, I am way more concerned about contacting a virus at the local supermarket than I am drinking filtered water in the backcountry. And the idea of a public bathroom door handle or a serving utensil at a buffet restaurant gives me the shudders in comparison. :-)

  • http://www.facebook.com/people/Steve-Lowe/1217265585 Steve Lowe

    I am new to the ultra-light packing world and was looking for a lighter way to procure water. I have an idea on something but now, having read all the comments here, I am second guessing it. I plan on using a Aquamira Frontier straw to filter my water and it filters down to 2 microns… Is that enough?

    If not, what about the 4 drops of bleach to go along with it.

    What grows at 1 micron or smaller that would be missed by this filter here in the thread or my frontier straw? I am looking to avoid taking my 14oz MSR Sweetwater filter and taking my Aquamira setup that weighs in at 2 5/8oz. My MSR is not rated to filter viruses and for two years with that filter I have had no issues. I do, however obtain water from fast moving streams. In only one area was the water source but a puddle. It was a dried up stream that had a trickle from the spring. This trickle was opening into a puddle and were many of us collecting water. Eather way, the MSR worked great. The puddle was dirty so the MSR clogged, but neither of the three of us in my group got sick.

    It is my understanding that we aren’t to worry about viruses. Are the viruses the nasty little critters that are smaller than the 2 or the 1 microns?

  • Christophe

    1 micron here and 0.2 microns for commercial filter like Katadyn…(sorry for the bad English I’m french) good blog! 

    • http://www.briangreen.net Brian Green

      Christophe, no need to apologize, your English is perfect and way better than my French even after 4+ years of studying it as a subject in England. Wish I had paid more attention to second languages. Thanks for your feedback!

  • Christophe

    1 micron here and 0.2 microns for commercial filter like katadyn…(sorry for the bad english i’m french)
    good blog! 

  • http://www.briangreen.net/ Brian Green

    Christophe, no need to apologize, your English is perfect and way better than my French even after 4+ years of studying it as a subject in England. Wish I had paid more attention to second languages. Thanks for your feedback!

  • Christophe

    I want to make and test your filter, it’s realy nice idear for do a light prefilter.  This filter can be used to extend the life of trade filter, or alone with chemichal treatement ( micropur and aquatabs say chemichal treatment is good only for clear water)
    Thanks for your blog! realy! I just brought the yellow paint for my titanium nails:)

    • http://www.briangreen.net Brian Green

      If you send me your address I’ll mail you a piece of the filter material I used to test with. Just don’t post your home address in the comments :)

  • Christophe

    I want to make and test your filter, it’s realy nice idear for do a light prefilter.  This filter can be used to extend the life of trade filter, or alone with chemichal treatement ( micropur and aquatabs say chemichal treatment is good only for clear water)
    Thanks for your blog! realy! I just brought the yellow paint for my titanium nails:)

  • http://www.briangreen.net/ Brian Green

    If you send me your address I’ll mail you a piece of the filter material I used to test with. Just don’t post your home address in the comments :)

  • Christophe

    wahhh! realy thank you Brian: mrdessin@gmail.com

  • Christophe

    wahhh! realy thank you Brian: mrdessin@gmail.com

  • Billy Matkovich

    This seems like it would be a perfect UL pre-filter to combine with a SteriPen! Actually, I like your fold-flat funnel and coffee filter as a pre-filter. It seems better than our bandana-over-the-nalgene method.

  • Pierre

    I tested some 1 micron biodiesel filters at home. Very funny and frustrating results. First attempt, with tap water, works fine – great flow. Then I let it dry and try again the next day and zero flow. I tried with three different pieces with same results.
    The only hypothesis I have now is that my tap water is quite calcium rich and is clogging the filter very fast??

    • http://www.briangreen.net Brian Green

      Yikes Pierre! I don’t get those results at all. Can you try doing the same thing with other materials like a coffee filter or something similar to the biodiesel filter material. That would help you determine if you have exceptionally “hard” or calcium rich water. Don’t give up on this as a filter just yet, maybe even try doing the same test with water from a nearby stream or river?

  • Pierre

    Hi, it takes time to test it as I have to let it dry every time but it seems the issue is not with calcium as the filters are not permanently clogged. In the first attempt the flow is immediate. In subsequent attempts water does not permeate the fabric despite using a bigger cone that you do (more water, more water column). I need to rub water in the fabric with my thumbs for a minute or so untill the fabric becomes a bit translucid. Then I get a good flow. 

    Unfortunately it means complete cross-contamination of the out side of the filter. Not a huge deal as I canlet some water drip through to clean it but it reduces convenience.

    • http://www.briangreen.net Brian Green

      Pierre, that’s just bizarre. I have not experienced that problem at all. The only other test I could suggest is to try again with a new piece of filter material and some bottled (controlled) water to see if it happens.

      Where did you get the filter material from in the first place?

  • http://www.briangreen.net/ Brian Green

    Pierre, that’s just bizarre. I have not experienced that problem at all. The only other test I could suggest is to try again with a new piece of filter material and some bottled (controlled) water to see if it happens.

    Where did you get the filter material from in the first place?

  • AHM122222

    A video clip of the very influential American preacher Yusuf Estes

    http://www.youtube.com/v/5J-9dn3_hpY&rel=0&autoplay=0&color1=bdbdbd&color2=bdbdbd&border=0

  • stormcrowgroup

    This is a very novel concept. I actually work specifically with water filtration and bioburden testing for QC Biopharma. Although the 1 micron pore size rating for the filter your using is very small, it is still a nominal pore size rating. The majority of filter materials, including cellulose ester membranes or sintered porous materials (little tiny beads fused together) are tested using the “bubble pressure test” method. It’s based on the theory that when you have a liquid pushing through a porous surface, it’s porosity is inversely proportional to the pressure in which the first bubbles appear on the opposite side of the filter. They base the porosity off this test, or also use a diffusion or standard water pressure test.

    A more useful test would be for someone to run samples containing known amounts of different microorganisms, running them through the filter, and enumerating the filtrate for microorganisms that have passed through (if any). This is something I do on a daily basis, hopefully someday I can get together a group of backcountry filters and run this “after hours” so to speak. ;)

    There’s always a chance that certain bugs will pass through, including Pseudomonads, which have a very “squiggly” cell morphology. They get through even the best 0.45um membranes which are used in pharmaceutical process control. There’s also the risk you run of the system not being perfectly sealed. Does the bottom filter have a seam or fold that water could pass around? I can’t tell form the pictures posted. You might also have to “clear” out or disinfect the 1micron filter after a trip, because you’re still effectively lodging bacteria within the pore structure. Running water and air in reverse through would be your best bet.

    On the whole, I think this is an excellent concept. But not 100% safe, which I know that you already know. It would probably be a 99.99999 (to infinity)% sure way to disinfect water if you used a SteriPen on your filtrate. It would increase the efficiency of the SteriPen dramatically, since you’ve cleared the water nearly completely.

    Let me know how this works out for you and shoot me an email if you want to talk more about it!

  • stormcrowgroup

    This is a very novel concept. I actually work specifically with water filtration and bioburden testing for QC Biopharma. Although the 1 micron pore size rating for the filter your using is very small, it is still a nominal pore size rating. The majority of filter materials, including cellulose ester membranes or sintered porous materials (little tiny beads fused together) are tested using the “bubble pressure test” method. It’s based on the theory that when you have a liquid pushing through a porous surface, it’s porosity is inversely proportional to the pressure in which the first bubbles appear on the opposite side of the filter. They base the porosity off this test, or also use a diffusion or standard water pressure test.

    A more useful test would be for someone to run samples containing known amounts of different microorganisms, running them through the filter, and enumerating the filtrate for microorganisms that have passed through (if any). This is something I do on a daily basis, hopefully someday I can get together a group of backcountry filters and run this “after hours” so to speak. ;)

    There’s always a chance that certain bugs will pass through, including Pseudomonads, which have a very “squiggly” cell morphology. They get through even the best 0.45um membranes which are used in pharmaceutical process control. There’s also the risk you run of the system not being perfectly sealed. Does the bottom filter have a seam or fold that water could pass around? I can’t tell form the pictures posted. You might also have to “clear” out or disinfect the 1micron filter after a trip, because you’re still effectively lodging bacteria within the pore structure. Running water and air in reverse through would be your best bet.

    On the whole, I think this is an excellent concept. But not 100% safe, which I know that you already know. It would probably be a 99.99999 (to infinity)% sure way to disinfect water if you used a SteriPen on your filtrate. It would increase the efficiency of the SteriPen dramatically, since you’ve cleared the water nearly completely.

    Let me know how this works out for you and shoot me an email if you want to talk more about it!

  • Don Meredith

    Brian, great post! You might consider using the bottom of a water bottle as the filter then epoxy two lids together face to face with a hole drilled in them so you can screw the assembly to a Platypus. If you’re adapting to a drinking tube you could epoxy a barb to a single cap with a mating hole in it.

    DM

  • Don Meredith

    Brian, great post! You might consider using the bottom of a water bottle as the filter then epoxy two lids together face to face with a hole drilled in them so you can screw the assembly to a Platypus. If you’re adapting to a drinking tube you could epoxy a barb to a single cap with a mating hole in it.

    DM

  • http://www.facebook.com/people/Lawrence-Mak/100003257119990 Lawrence Mak

    No doubt we
    need a quality water purifier for drinking needs, some water purifiers has
    reverse osmosis membrane filter which has pore size as small as to 0.0001
    micron, so it can filter out the most contaminants, i recommend Coway water
    purifier.

    http://www.cowaywaterpurifier.com/

  • http://www.facebook.com/chadgoodmanparker Chad Parker

    I’m looking for a quick solution to preventing death by neti pot via brain eating amoebas. Rather than purchase distilled water or take the time to boil water, I’m considering simply filtering hot tap water. Does this sound like a sensible use for your filter model? As long as it filters in less time than it takes for water to boil and then cool down enough to put in my nose, I might be willing to give this a try. How is the longevity of the filter? I’ll be using it on tap which probably will get better results than actual dirty water.

    • http://www.briangreen.net Brian Green

      Unless you’re in a third-World country, tap water is safe to drink. The filter lasts a long time, can be cleaned, but is cheap enough to make several and carry backups.

      • http://www.facebook.com/chadgoodmanparker Chad Parker

        That’s true, but it’s not necessarily safe to irrigate your nose with, thanks to a certain amoeba. There were a couple deaths in Louisiana from neti pot usage, which seem to be alone in the literature, but my friends and family are urging me to be safe rather than sorry. Thanks for the tips.

  • http://www.facebook.com/chadgoodmanparker Chad Parker

    I’m looking for a quick solution to preventing death by neti pot via brain eating amoebas. Rather than purchase distilled water or take the time to boil water, I’m considering simply filtering hot tap water. Does this sound like a sensible use for your filter model? As long as it filters in less time than it takes for water to boil and then cool down enough to put in my nose, I might be willing to give this a try. How is the longevity of the filter? I’ll be using it on tap which probably will get better results than actual dirty water.

  • http://www.briangreen.net/ Brian Green

    Unless you’re in a third-World country, tap water is safe to drink. The filter lasts a long time, can be cleaned, but is cheap enough to make several and carry backups.

  • http://www.facebook.com/chadgoodmanparker Chad Parker

    That’s true, but it’s not necessarily safe to irrigate your nose with, thanks to a certain amoeba. There were a couple deaths in Louisiana from neti pot usage, which seem to be alone in the literature, but my friends and family are urging me to be safe rather than sorry. Thanks for the tips.

  • Jarm

    I know that I am late to the game here but my major concern is the manufacturing process of the filters might leave residual chemicals behind in the filter media. In a diesel setup, it doesn’t matter because they would become part of the exhaust. For human consumption though, they would get into your water and into you causing issues in the long term… Just a bit of food for thought.

  • stanley mckinney

    Thats what Im doing here. Im using the bio filters and a steri pen as a second defensive . There r on holes in these filters only folds . I would like to know the results of your test if you could pose one after hours:)

  • http://www.facebook.com/billy.weinman Billy Weinman

    I’ve used the system for over a year now, from water sources of all kinds, without ill consequences. One thing i experienced last winter, however, was that the water filter may freeze if temps drop too low, and then it can not filter. In that case, i had to boil enough water on my bushbuddy to stick the filter into and thaw it. then it worked fine. Another great plus, is that the entire filter can be boiled clean again when needed. It will pick up cooking soot and other crap, but using the double yogurt system of djbarry, I have been pretty pleased for such a simple system.

  • Gobblin

    Neat idea, but raises a question for me. If you’re treating the water as well, why the need for the bio-fuel filter? You could just use the 2 other components to filter out the ickies and improve the taste. Pour the water through the coffee filter into the bladder and then pop in a tablet. That’s what I do. Even less weight and still improves the taste by filtering out most of the crappy stuff. JMO based on my experiences.

    • http://www.briangreen.net Brian Green

      I can’t argue with your logic. I dunno, it was more a matter of doing it because I wanted to make this and see what it would be like – just because I could ;)

  • Jenny C

    OK, since seeing this earlier today, it has been on my mind non-stop.
    I made a comment about the necessity of using chemical treatment after using a water filter (and I think this filter is equal in capacity to other marketed filters)
    …but I Truly can’t stop thinking about how to ensure the contaminated side of the filter doesn’t come into contact with the ‘clean’ side- directly or indirectly (the water from the one side coming into contact with the other side in storage)? Then I got to thinking, do we need such a large filter surface? The larger the surface, the longer it can be used, true- but how long do we want to reuse the filter for in reality? Wouldn’t a smaller filter that can be changed out regularly be more space, weight, and cost friendly?
    So after chewing on it for a while, this is what I came up with (SEE IMAGE)
    Basic setup would be: the cut of top of a 2-liter bottle with a pop-up bottle cap. Held upside down, a coffee filter (or other filter) would be placed in the top and a round cut piece of the .5 micron filter material would be placed between the top of the bottle and the bottle cap.
    BENEFITS:
    *Wide opening for incoming water
    *Narrow outflow (would fit in my Gatorade bottle or water could stream into smaller bottle)
    *The clean and dirty side of the filter would not come in contact
    *Coffee filter (or other initial filter such as nylon) could just be laid in the top and left there until a new one is needed.
    *The whole thing could be stored in a mesh bag, with the nozzle down and attached to outside of the backpack- the inside would dry out quickly exposed to the air so no need for contaminated part to touch anything else ever.
    *Additional small circular filters and coffee filters would be lightweight and easy to store.
    DOWNSIDES:
    It couldn’t be collapsed flat for storage
    CONCERNS:
    *Would the flow rate be seriously compromised with a small filter surface?
    *The small circular filter would need to be cut large enough so there would be no small gaps off to the side of the filter where unfiltered water could get through (a snug compressed fit between the diameter of the bottle opening and the bottle cap lid).

  • Christian “caveman” Miller

    I really like this idea. I jut bought a 7″ x 32″ 0.5 micron filter bag and with this way of filtering my filter bag would last a really long time bc it only needs to be cut into tiny circles . I’m really glad I decided to read all of the comments haha.
    Jenny C your a genius in my eyes ;)

    • Christian “caveman” Miller

      I just had a thought to make this idea even better. How about first adding a mesh tap filter from your kitchen tap which is basically the same size as the bottle cap which would help prefilter and then the 0.5 micron piece. I don’t know. just my two cents