Water filters/purifiers. . .

S

Salamander42

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Mar 21, 2007
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I need to buy a filtration system for hiking, and I've been wondering. . . do water filters/purifiers like the popular Katadyn and MSR models do anything for non biological contaminants? I'm thinking specifically of the possibility of contaminants from an aluminum plant near a nature preserve that I go to in southern Indiana, but also wondering about fertilizer run-off and other chemicals. Also, I wonder if I would safely be able to filter water from one of the ponds in my apartment complex in an emergency situation. . . or any other source of water in the city. . . no telling what kind of household chemicals and automotive fluids and other nasty stuff might be in there.
 
Why don't you go to their websites? Here's what came up for the MSR Sweetwater Microfilter that I have.

About Sweetwater Microfilter
The Sweetwater Microfilter eliminates over 99.9999% of all waterborne bacteria and 99.9% of common protozoan parasites such as Giardia and Cryptosporidium. It comes with a stainless steel prefilter, two color-coded silicone hoses, foam float, water bottle adapter, cleaning brush, and carry bag.

Purifier vs. Microfilter
A water "filter" generally claims to reduce or eliminate protozoan parasites and bacteria. A filter is adequate for remote wilderness seldom visited by people.
A water "purifier" also removes or inactivates viruses and is therefore ideal in any situation.


Chad
 
I do know that the carbon core of the MSR removes the nasty taste of chlorine, iodine and other chemicals. I would think the answer would be no because it only filters down to .2 microns. Chemicals would be at a molecular level.
 
I know that I put Pepsi through a filter bottle and some bad taste and coloring remained. I think you would be up the creek on chemicals. That would probably be and argument for a lightweight still of some sort.
 
It depends. Some chemicals will bind to the activated charcoal element and be removed that way. On the other hand, it's effectively impossible to "filter" out dissolved ionic compounts - for example, salt. There's nothing to be filtered since the compound dissociates into cations and anions when in solution. It can be done with some fancy techniques like reverse osmosis, but not with a simple filter. So the short answer is no, don't rely on backpacking filters to treat chemically contaminated water.
 
Any Cal. said:
I know that I put Pepsi through a filter bottle and some bad taste and coloring remained. I think you would be up the creek on chemicals. That would probably be and argument for a lightweight still of some sort.
Click to expand...


The still will work for compounds that remain solid at the temperatures used, but what about liquid contaminants that have a boiling point near that of water? Unless you can exactly control the temperature (impossible outside of a lab, e.g., in the wilderness), you'll end up with other chemicals in your distillate.
 
Any Cal. said:
I know that I put Pepsi through a filter bottle and some bad taste and coloring remained.
Click to expand...

Who's filter bottle? Most of them are in the 1 micron range and none I've seen have a carbon layer; a decent filter is a .2 micron filter and the very good have activates charcoal (carbon) as part of them. Comparing a good hikers filter to a filter bottle is like apples and crab apples. Yes, you can see the line of evolution, and you can see a lot of evolution that didn't happen to the poorer one.

I would also be suprised if there was any filter that was able to completely block a coloring agent. Most of them are much smaller than any known biological, when taken as a molecules. If you are expecting filtered water to be the same as distilled or reverse osmosised (is that a word?) water, you're going to be waiting for a while.
 
No, I was hoping for something like that at the time, but now I know better. My point was simply that I would expect waterborne chemicals difficult to remove, just like the dyes, so probably beyond the limits of a filter bottle.
 
ironraven said:
Who's filter bottle? Most of them are in the 1 micron range and none I've seen have a carbon layer; a decent filter is a .2 micron filter and the very good have activates charcoal (carbon) as part of them. Comparing a good hikers filter to a filter bottle is like apples and crab apples. Yes, you can see the line of evolution, and you can see a lot of evolution that didn't happen to the poorer one.

I would also be suprised if there was any filter that was able to completely block a coloring agent. Most of them are much smaller than any known biological, when taken as a molecules. If you are expecting filtered water to be the same as distilled or reverse osmosised (is that a word?) water, you're going to be waiting for a while.
Click to expand...

There are several bottles with carbon elements, but a lot of them are more like 2 microns-- barely enough to trap Giardia. IMHO, the Katadyn bottle is the best of the lot, but I still use a pump or chlorine dioxide (Micropur or Aqua Mira). If they made a bottle that was effective, you would suck your face inside out trying to draw water through it :)

As to coloring agents, the First Need pumps were sold with a bottle of blue food coloring so you could test the filter. It is a great way to see of the cartridge is cracked--- ceramic cartridges can be broken and then you are unknowingly pumping without purifiying. I've camped at Cape Alava on the Olympic National Park coastal sections and the stream water there is heavily tinted with tannin, which the First Need filter removed. It just depends on the size of the coloring agent.

I got a Katadyn Hiker Pro on sale at REI for what the bottle costs. They include quick release fittings so you can pump into your hydration bladder without removing it from the pack. 11 oz-- not bad for a pump.
 
The filters that have a charcoal element do help with a lot of chemicals. The activated charcoal has a tremendous surface area that will absorb a wide variety of organic (insecticides) and inorganic pollutants (many heavy metals ect). Not all of them of course! As noted earlier though, the activated charcoal has a fixed capacity and will become overloaded when subject to a very high load (e.g. the pepsi example - neat observation!) or cumulatively over many uses. Even some freely dissolved ions are well trapped on activated charcoal. The main reason britta filters are successful in households is due to the capacity of activated charcoal to remove residual chlorine making water taste fresher.

Since you cannot replace the charcoal filter on most of the backpack water filter systems then you never know the operating efficiency of your unit. Also, the charcoal filter is added to these systems to help with taste/odour problems but not specifically designed for trace pollutants which would require a lot more charcoal. Not knowing the contaminant type and concentration in a given system would thwort engineering attempts to make a weight-practical purifying filter for pollutants other than biologicals.
 
The bottles with the carbon must be new, or just haven't noticed them in the catalogs. But at 2 microns.... uhm, yeah, I'll just treat normally.
 
Thanks to everyone for your thoughts. I'll just continue carrying in my water when I go camping anywhere where the streams might have fertilizer or other chemicals/contaminants in them, and I guess stockpiling a few days worth of water is still the best for preparing for an urban emergency/survival situation.
 
My first advice is never drink down stream from the herd. Or the aluminum plant. I will add several links including HTI. This and similar products don't produce water but the end product is a sports drink. The filtration ability is amazing and well worth the cost if suspect water is a problem. The Army site is a gold mine of information. Once you review the linked page start at the beginning and read it all.



http://usachppm.apgea.army.mil/wpd/CompareDevices.aspx


http://www.safariquip.co.uk/i_water_treatment.html


http://www.hydrationtech.com/skipped.html


http://www.hydrapak.com/technology/features.shtml


http://news.com.com/Technology+may+...rumID=1&threadID=9307&messageID=67099&start=0
 
You're right, that Army site is awesome. I had no idea how crappy the prevalent Potable Aqua tabs were. I need to go find some of those Katadyn tablets.

I was comforted that my Sweetwater is a pretty effective filter though, so that is nice to see.
 
ironraven said:
Who's filter bottle? Most of them are in the 1 micron range and none I've seen have a carbon layer; a decent filter is a .2 micron filter and the very good have activates charcoal (carbon) as part of them. Comparing a good hikers filter to a filter bottle is like apples and crab apples. Yes, you can see the line of evolution, and you can see a lot of evolution that didn't happen to the poorer one.

I would also be suprised if there was any filter that was able to completely block a coloring agent. Most of them are much smaller than any known biological, when taken as a molecules. If you are expecting filtered water to be the same as distilled or reverse osmosised (is that a word?) water, you're going to be waiting for a while.
Click to expand...

Basicly if it's disolved in the water (like salt or the stuff in Pepsi) it won't be filtered out. It's part of the water. If it's smaller than the filter size (.1 micron) it'll go thru the filter. So you gotta drink it. If it's alive (virus) you gotta kill it by boiling or with tablets.

Or distill the water.
 
HTI and others will filter out salt etc. You must pick the propper filter for your situation. Read my links and make your choice.
 
Thanks for the links 2dogs! That HTI system is pretty nice. I haven't had a chance yet to do more than just skim through a little of the info that you've provided. Hopefully I'll have time to do a little more reading tonight.
 
Sal you're welcome. Remember that the HTI produces a sports drink and not plain water. In addition you have to carry a liquid syrup. Some pollutants, like those maybe in your water source, are concentrated by boiling and not removed by conventional filters. Your best bet may be to contact a local water lab and see if they can test your water. The cost is reasonable and I for one would like to see the results. Good luck.
 
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