particulate filter during chemical purification?

Particulates that you can see with the naked eye are relatively easy to filter out. See my "bottle cap filter" at Jason Klass' webiste:

http://www.freewebs.com/jasonklass/waterbottlefilter.htm

OTOH, for green algae-laden water or brown river water, much more sophisticated filtering is going to be required if you want clear drinking water.

Hi Michael,

You can use fabric, such as a bandana, a piece of nylon stocking or piece of bug mesh, across the container opening to keep out larger debris (the visible floaties and swimmies). e.g., Meridian Design includes a drawstring mesh bag with their UV purifiers that works well.

Please note that very fine particles will still pass through, so avoid murky source water if you can.

I use a two step process, a paper coffee filter, then Katydin Mircopur. The filter is very coarse, but I have never needed to drink cloudy water, and if I did it would be a serious situation and wouldn't worry about drinking some inert particles once the Micropur had done its thing.

Brett:

Are there metallic mesh coffee filters in Japan? If so, give them a try. Paper holds on to water, and the drip through is thus excruciatingly slow (especially considering what a diehard Caldera stove speed demon you are). The metallic mesh is just as effective, but allows you to pour the water right through! Give it a try.

The tight weave cloth used to make Indian saris, is used in
3rd world countries as one step in removing particles that
house cholera. Filtering through two layers of sari cloth
and then settling over a period of 3 days in 3 different pots
(pouring off the good water from one to the other after a day)
has proven effective at removing cholera.

So, a single layer used as a prefilter should work well.

I just bought a funnel/filter for Coleman fuel for $1+ @WallyWorld. It has the tiniest metal mesh I've seen and will try it in lieu of the paper filters I've used. Should be easier (no special method to keep the paper from folding/moving.) It's very light.

I've run it thru several cycles in the dishwasher just in case there are some chemicals from the manufacturing that I don't knkow about!!

100 µm FDA-grade polypropylene mesh filter bag, trade size 3 (4" diameter x 8" tall), 0.8 oz.

There are filter bags available with pore sizes down to 1 µm, but the ones smaller than 100 µm are made of felt rather than mesh and hold on to a lot of residual water.

Maybe I should start a new thread instead of changing the subject a bit, but if you are using a Platypus hydration (Hoser) system, what is the best way to get the water from the stream into the bladder? And with such a small opening, you would have to filter the gunk before pouring it in I would think. Any Hoser users out there figured out a good solution?

The fuel filter above works.

Todd:

Not sure if you clicked on the link in my post above, but if you modify your fuel filter into a bottle cap, then it will be even easier to use — and much more compact than carrying the fuel filter itself.

Fuel filter aside, one can also get the same wire mesh material from coffee filters:

Ryan:

Try this. Make a screw-on bottle cap filter for your Platy Hoser as shown in photo above. Next, sacrifice an old 1L platy by cutting the top off — at a slant. Voila — you've just made yourself an ultra light and compact water scoop! When you encounter shallow streams, just scoop with the cut off Platy, and pour water through the bottle cap filter into your Hoser.

Ben,

Ya know I've seen your idea on Jason's site before and for some dumb reason just never put it all together in my mind. Very creative!

Ryan, I too use a cutoff Platypus to scoop – it's the best thing I've found, especially for shallow sources.

I got sick once from water, so I now zap w/a Steripen Adventurer after "filtering". Even w/the Adventurer my treatment setup weighs less than any pump filter I ever owned.

Benjamin:

I just read your instructions on the Jason Klass site. A couple questions:

1) When you unscrew the filter cap, how does the mesh stay in there? Won't it fall out?

2) I'm not a coffe drinker – so I don't know – but I would assume you can buy just the wire coffe filter by itself? Is that cheap?

Ryan:

You can buy the coffee filter by itself — and pretty cheaply at Wall-Mart, etc. Todd's fuel filter is even cheaper if all you need is one bottle cap filter. I cut a round piece off the filter in a size just larger than the cap itself — and jam the filter in. It won't fall out by itself.

Todd:

Glad it works out for you! Yeah, the thing is good only for filtering sediments — definitely won't do a thing against bacteria. Curious, assuming that you also use narrow-mouth platys — my understanding is that the UV tube isn't really long enough to be effective. I recall (somewhere) that the UV is better suited for wide-mouthed containers where it can reach in and be stirred all around???

Ben,

You are correct on the way to use UV. My method for using the Steripen Adventurer is:

1- Scoop w/a cutoff Platy
2- Pour thru a paper/screen filter
3- Step 2 pours into a Big Zip platy w/cap
4- UV-treat thru the zip opening
5- pour (via spout)into gatorade bottle, Platy, Nalgene cantene, whatever

Using the Big Zip (2L?) size lets me collect all the water I need. It also lets me avoid carrying a hose attachment, etc down to the water source (like you mentioned in another thread). I also like the handles for carrying / hanging.

Todd:

Thanks for the quick feedback. I didn't know Platy has a Big Zip model with a bottle cap opening? I thought it's a big zip on one end, and just a little "nipple outlet" to connect with a hydration tube at the other end?

No experience with the Big Zip, but I dislike the idea of having to drag the hydration tube down to the river bank every time I need to refill. I just know that I'll get dirt and stuff all over the tube and bite valve…

But if it's a Big Zip with a bottle cap opening, then I will definitely look into it more.

I use 1L standard platypus with a Steripen (the white one). What I do is turn it on, jam the business end into the platypus opening, invert the platypus and hold/swirl for the time it takes. Never had a problem. I usually have a wool cap or bandana with me which I cover the platypus with. Makes it so I can't see the light which should be more UV in the water and less in my eyes (-:

Does water leak out when you invert and swirl your Platy?

Like Ben said. : )

I used a big ziplock bag to collect shallow water and poured it into a Nalgene and then used the Adventurer. I like this entire idea better with using with cut up Platy for scooping or carrying water.

I wonder if the Adventurer is slimmer and not jam as well into the spout.

After some practice the first day, no I do not get leaks.

The white steripen at least seems a perfect fit, can't speak to the adventurer (yellow one).

The only "trick" is to jam it in good and rapidly invert the whole thing. The neck and the blue rubber section seem to marry quite nicely.

Thanks, Sean. Good to know.

Todd-
After reading your method, I am understanding that you only use the Big Zip 2L Platy as a canteen and not as your main water container to drink from while hiking. Has anyone hooked up a drinking tube to a Big Zip canteen?

Also, I guess you scoop up a liter, pour into the 2 L, treat and then once that amount has filled your other bottles, you scoop up another liter to treat. The Steripen treats only a liter at a time. Am I missing something?

My method just fills a 3L Dromlite for camp, pour out a liter into my Nalgene (now it will be a Platy) and treat that.

Yes, I have one of those 'permanent' metal filters but the holes are too large for some of the grounds, so the coffee end up with bean dust (dregs?). Not a tragedy, but I have found that paper filters have the tightest weave, and easy cleanup. The 4 cup size fits with its circumfrence folded firmly over the edge of my Snowpeak 600 mug perfectly. I also tried the Snowpeak OD Drip, a cloth folding mesh filter, but again, holes too big. My grinder is not too precise, so either of those solutions would work with a more precise grinder.

Hi Donna,

Yes, you understand me. WOW – I haven't said that often!!! I pour thru the paper or mesh filter into the 2L.

It's easy enough to hook up a hose…no problem. My reason for not doing so is fear (albeit Unfounded) of the zip coming open in my pack while filled w/water!

I got sick once from water (That SUCKS) so I'm a little paranoid anyway. Water scares me almost as much as females (I'm married w/THREE daughters :)