I'm thinking about worse case scenarios,where one doesn't have a choice.My filter removes bactieria and viruses.But what about chemicals,like field run-off or chemicals from an upstream chemical factory or paper factory.

-- zoobie (zoobiezoob@yahoo.com), August 05, 1999

Answers

and would boiling do any good?

-- zoobie (zoobiezoob@yahoo.com), August 05, 1999.

depends on the chemicals eddy

-- eddy (xxx@xxx.com), August 05, 1999.

Does it depend on the size of the particles? Don't most rivers and streams have run-off--of something?

-- Mara Wayne (MaraWAyne@aol.com), August 05, 1999.

Camping filters only filter out particles above a certain size; the Katadyn filters to 0.2 Microns, as I recall (I have one which I've used for years in Latin America). I don't know of any which filter anything any smaller than this.

This is still not small enough to filter out viruses (not by a long shot) I believe there are some brands which claim to kill viruses by having silver impregnated filters of some kind. Check with, for instance, REI,

Filtration will NOT remove dissolved chemicals! Boiling will basically tend to CONCENTRATE dissolved chemicals, since some of the water evaporates when you boil it, and the chemicals generally do not.

Hope this helps.

Al

-- Al K. Lloyd (al@ready.now), August 05, 1999.

Some of the camping filters include a charcoal elements which will take out some chemicals. They don't claim to do it real thoroughly but they do say it will make it taste better...Whether boiling will help just depends on whether your particular contaminant has a higher or lower boiling temperature than water. If lower, I would think a light simmer could boild off some chem without losing as much water. On the other hand maybe a simple still could get you water without any higher-boiling-temp contaminants. I'd like to find a good source for activated charcoal to make a great big makeshift chemical filter but don't know where.

-- Shimrod (shimrod@lycosmail.com), August 05, 1999.

Zoobie,

I have read the answer is basically, no, you can't get the toxic or radioactive stuff out of water by filtering it. Even visuse, if memory serves, can be so small almost no filter will work. We're talking a strand of DNA! Chlorine doesn't work well with cyst. I'm thinking filter the water thru a good ceramic filter, then disinfect it with bleach.

FWIW,

-- Louis (StLouisLouis@Yahoo.com), August 06, 1999.

if you do not know the certain chemicals, the answer is no! don't try it!..but what do i know, i'm a chemist eddy

-- eddy (xxx@xxx.com), August 06, 1999.

Zoobie:

The mix of information above is essentially correct. Doing what you want to do is essentially a crap shoot; without analysis. The 0.22 5 filters will not remove a virus; if purified. In real life, most of these particles are bound to something too big to go through the filter and you will decrease the viral load. I don't know what contaminents you have in your water [are you going to NM], but you must have charcoal filtration and ion-exchange to be somewhat safe. Or you could do what our early relatives did; take your chances.

-- Z1X4Y7 (Z1X4Y7@aol.com), August 06, 1999.

Im an experienced backpacker and did quite a bit of research on filters. We live in an apartment in a country area along a river, so my water solution is to purify. I picked up an MSR Miniworks and Waterworks, with enough filters to carry 1600 gallons. My friends have many types of filters which has given me some insight into their operation. Below are my impressions of each and why I bought an MSR.

For years I used a First Need, later went to a Sweetwater (now out of business). The First Need is a great filter but is heavy (consideration only to backpackers). Im not sure if it has a charcoal filter but it claims to be able to filter out many chemicals including hydrocarbons. It is somewhat awkward to use and I spilled my fresh water container more than once in the process of filtering. I then went to a Sweetwater but this had the annoying habit of spraying water when pumped to fast. First Need filters are hard to find and of course the Sweetwater is no longer made.

My requirements were thus; to have a filter that can be put into a puddle of excrement and pull out clean water. I wanted a bottle top adaptor like my Sweetwater, and a charcoal filter that would take out iodine/bleach, since the water might be treated like this prior to filtering. I have a good amount of respect for this aspect of survival. Ten years ago I was in the hospital for a week with what was probably a parasitic infection from the Catskills. I treated the water with iodine AND a filter, and still got sick. More than likely, a drop or aerosol particle of contaminated water got on the threads of a bottle being filled.

A friend has a Katadyn. Ive tried both models and they are VERY hard to force water through, but very durable. The disadvantage is that the Katadyn will not take out viruses and has no charcoal filter, which will take out some chemicals. The Katadyn mini has two models, regular filter and charcoal filter. Cant have both. The filters treat an emormous amount of water in their lifetime. I didnt buy a Katadyn because the filters are imported, and they are difficult to pump (I consider this important, after using my friends for 4 days). To treat for viruses and iodine I would have to use iodine, THEN the filter, THEN another charcoal filter like a Brita. They are also pretty expensive and I wanted to buy a backup. In the event Y2K blows over, my spare is going to be donated to missionaries in the Soviet Union, and I didnt want to go nuts with the expense.

Two friends have Pur. Great for virus protection, however there is no way to tell when the iodine matrix has lost its effectiveness. The filters are also paper which I have read is subject to tearing while filtering in some tests. In cold backpacking climates this can happen more frequently. They pump very hard compared to an MSR. Finally, I want to remove all chemicals from the water to avoid liver damage.

I spent about 30 minutes on the phone talking to MSRs Waterworks designer. There are a number of attractive features for the Mini/ Waterworks. - Screwtop adaptor so dirty particles are sealed off from the filter process. - Clear filter body. - Filter replacement gauge built into the body. - Ease of pumping! - Inner core of charcoal under the ceramic filter, to remore chemicals. - Miniworks is used by the US military after tests. - Entire filter can be disassembled. - The designer told me that although the packaging states filter to .02 micron, most particles are caught at .01 and they are doing more tests to make that claim. - The relatively inexpensive filter and cartridges ($30) might be used for barter. - MSR says that all filters are produced at one small plant in the US, and with current (hopefully compliant) technology. -Overpressure relief valve to avoid injection of contaminated water.

The disadvantage of the MSR is the number of parts, which can be lost during repair. The filters also only get about 150 gallons per. They also obviously require an iodine pre-treat to kill viruses. Ive used the filter in human excrement-exposed water (found out after filtering that some yuppies were crapping and peeing into the stream at a campsite up from us) with no ill results. My friend used his Pur during this incident and also had no aftereffects.

MSR makes dromendary bags which screw on the filters. They are black and heat up water pretty well, as this is a consideration in New England.

-- Retroman (retro50@agapeis.net), August 06, 1999.