anyone ever use a cone shaped coffee filter to take the big contaminents out of water? or other liquid. seems they might be handy.

not to replace purification, just to strain the chunks out!

It's just easier for me to carry at least two bandannas - good for 1001 uses.

some of the lakes in canoe country harbor water fleas..Daphnia. harmless,but who wants "swimmers" as they
are also called in their drinking water--soooo--yes..i
have used a coffee filter to strain them out..very slow
process but it works..maybe a cheap filter would work
faster than the Melttia's which seem to have a fine weave.
i have also used "jam bags" or whatever they are called
in your part of the world..they are found among the wax
and canning jars section--they fit in a metal strainer gizmo
for making jelly--draw string top--very handy and cheap..i
use one to carry a fishing reel around in my pack..

Not a cone, but a regular basket shaped filter. I was less than thrilled with it (hard to hold in place), I went back to a bandana...

for drinking water i carry a millbank filter ( http://outdoors-magazine.com/spip.php?article257 ) A purpose made cloth filter, which is very effective in removing particles, very reliable and you can toss it in the washing machine to clean it.

Does anyone know where you can purchase the millbank in the USA

Unless I'm missing something important, isn't the Milbank filter simply a tightly-woven canvas bag with a handle? All it has to do is filter out the chunks -- it doesn't have to catch viruses.

Wouldn't they be simple to make?

Sue

Here http://www.survivaltopics.com/survival/making-water-safe-to-drink-video/ is a nice video on water purification. He covers the Millbank Bag (very cool, I think I'll get one), but like most people, when he gets to water boiling OR water filtering, it is just that; either or. My point is that most experts seem to adequately address the pathogen issue but they seem to completely ignore the chemical contaminant issue. I think it is worthwhile these days to consider these steps:

1. Millbank Bag to remove debris;
2. Boiling to kill pathogens;
3. Microfilter to remove heavy metals and other contaminants.

As far as my research is concerned, disinfection via iodine or other means is not universally effective enough to rely on, so I don't mention it.

Step 2 could be eliminated if there is a microfilter that effectively removes all pathogens.

My first question is; How do pathogens and heavy metals and other pollutant molecules differ in size? If recall correctly, viruses are the smallest pathogens. I have no clue regarding pollutants.

My second question is regarding step 3, and is two-fold; Are heavy metals and other potential pollutants a concern to anyone, and is there a microfilter that is known to effectively deal with these?

Heavy metal atoms and pollutant molecules are tiny compared to viruses. Remember, viruses are made of millions/billions of molecules. Molecules are made of two to millions of atoms. For the everyday user, we can stop at atoms.

-Blast

well the millbank bag is indeed made of a very tightly woven canvas, which swells up when you pre soak it for use. It's also threatened to prevent it from getting moldy. It's very simple and indeed easy to make.... if you can find the right quality cloth.

I've heard about those bags clogging up very easily, is this true?

well not really, they have larger surface area than a ceramic filter and larger pores. Generally not an issue with reasonable clean water.

I did manage to clog mine millbank once, but that was with muddy water from a car track in the forest. I also had to clean out mine MSR miniworks 8 times that day, filtering that water, with a fine towel on the inlet...

PC2K, could you tell me what the dimensions of the Milbank filter are, and how long it takes to filter a specific amount of water? I would like to try to make one. Thanks.

Sue

well they come in various size's and the rate the water flows is depended on the size of the bag and the quality of the water. The size on mine is: 20cm wide and the length on the long side is 44cm and the shorter side 33 cm. ( i only do metrics's, no ruler in sight with inches on them)

Never really measured the flow. With tap water, usually a slow stream of water. The bigger models are faster, than the smaller ones. With mud from a car track, this will slow down to a drop every 30 second until the millbank is totally clogged up. The drops however where 100% clear looking.

According to the University of Rhode Island, coffee filters have a pore size of about a hundred microns. (http://geo.uri.edu/skydust/faqs.aspx)

Depending on what you mean by big contaminants, a coffee filter might work. If I ever have to use my ceramic filters to purify water, I certainly will pre-filter the water that goes into the reservoir for the ceramic filters. I'm not sure I'd use a coffee filter, but I'll use a strainer of some kind.

Okay, that's about 17.5"L x 13"W with an 8" diameter opening.

That sounds like three bags out of a half-yard of fabric. Plus the hanging handle.

Thanks!

Sue