I'm seeing a lot of new threads about water purification systems, and realized it's an area I'm severely lacking in knowledge. When hiking, I've always brought enough clean with me, and planned on boiling if I ever needed emergency water. For Bug In, I would rely on a gallon of Clorex and an eye dropper and/or boiling. So I started to do some research, and now I know less than I did before <img src="/images/graemlins/shocked.gif" alt="" />

Here's what I've found, and what questions I have. This is based solely on the Katadyn web site, since that brand seems to be the consensus choice.

Technology: ceramic, carbon, glass fiber and combination. What does each do that the others don't, and why would I want one over the other?

Nasties: What bio hazards do I need to filter out? Gardia seems to be the boogeyman, but I'm also hearing about filtering viruses. How the heck do you do that?

Capacity: Does that mean how much you can run through before changing filters?

Size: Is there a size that would fit *most* situations short of a full blown SHTF? I'm thinking of something that would work for hiking but also for a few days of camping or home problem scenario. If not, should I be looking at two models?

What questions haven't I asked that I should have?

RE Technology:
There are two basic types of filtration you've touched upon there; filtering for biological contaminants and filtering for chemical contaminants.

Think of Ceramic and Glass Fiber filters as screens. Biological contaminants have a minimum size and the pores in these two types of "screens" are smaller than those contaminants so they are unable to pass through the filter with the water. Note that viruses due to their extremely small size can still pass through many of these filtering elements.

Several companies are also testing silver in particle filters because it seems to be able to kill the biological contaminants. I don't know much about its effectiveness.

There is also the chemical treatment option to kill biological contaminants, which either use Iodine or Chlorine. Since we're talking filtration, I'll skip those.

Granulated Activated Carbon on the other hand filters chemicals out of water (Toxic Contamination). Carbon by itself will absorb a very large number of different chemicals, and activated carbon has been electro-positively charged making it "attract" even more. It's granulated to offer more surface area IIRC.

RE Nasties:
To quote from ETS: "Most bacteria are larger than 0.5 microns in diameter, but some are as small as 0.2, though the ones most likely to cause problems tend towards the larger size."

Viruses on the other hand are a whole other ball of wax depending on type. They can be smaller than most filters can screen. However, Iodine and Chlorine can kill viruses. Read the link to ETS above for more info on this.

RE Capacity:
Yes, capacity generally refers to the amount of water that can be safely filtered before the filter must be cleaned or replaced.

RE Size:
This one is really up to you.

I carry a Katadyn Pocket Filter when I go camping, which resides in my small BOB. It has a .2 micron silver impregnated ceramic filter a capacity of 13,000 gallons and will filter 1l/m. I also have a Katadyn Inline Carbon Cartridge to supplement the Pocket Filter (200 gallons before GAC must be replaced). Together they can filter just about everything nasty out of water except for viruses. I could either pretreat or post treat the water with Iodine or Chlorine to take care of the viruses. I will admit that I don't do this though. Thus far, knock on wood, the Katadyn Pocket and Carbon Cartridge have been enough.

You know... I should have just given you the link to the ETS Info on Water Purification and Filtration right off the bat. It has all the info you were asking about and more. <img src="/images/graemlins/grin.gif" alt="" />

My micro filter knowledge is a little dated but most of it still holds true...

Katadyn is the brand ofchoice because they have been slowly buying up other brands like PUR. This left Katadyn, MSR and SweetWater as the major players.

Filters themselves-
First off NO filter filters viruses. PUR used to sell the Explorer series that leached iodine to kill the buggers but those have been discontinued when they where bought over. You have to chemicly treat water or boil.

It used to be that Ceramics where cheaper, had a slower flow rate, and is silted up in the field were basicly toast. Fibers were almost twice as expensive as ceramics but could be "brushed" if silted up and flowed a little faster. (that info is few years out of date and things might have changed)

Carbon- This is usually post filtering using active carbon to remove chemicals and bad tastes.

The capcity is how many gallons or liter you can get out of 1 filter.

Gairdia is teh boogeyman because its all over the place.
http://www.cdc.gov/ncidod/dpd/parasites/giardiasis/factsht_giardia.htm
"During the past 2 decades, Giardiainfection has become recognized as one of the most common causes of waterborne disease (found in both drinking and recreational water) in humans in the United States . Giardia are found worldwide and within every region of the United States."

To make things worse

"What are the symptoms of giardiasis?
Giardia infection can cause a variety of intestinal symptoms, which include

Diarrhea
Gas or flatulence
Greasy stools that tend to float
Stomach cramps
Upset stomach or nausea.
These symptoms may lead to weight loss and dehydration. Some people with giardiasis have no symptoms at all.



How long after infection do symptoms appear?
Symptoms of giardiasis normally begin 1 to 2 weeks (average 7 days) after becoming infected.



How long will symptoms last?
In otherwise healthy persons, symptoms of giardiasis may last 2 to 6 weeks. Occasionally, symptoms last longer."

Here comes my opinion.
I would get the Guide series over the Hiker line.
Guide-Wt 14 oz. Ht 9.5 in.
Hiker-Wt 11 oz. Ht 6.5 in.
Its only 3 oz and 3" taller but pumps faster and the T handle is alot easier to use.

I also recommend you use a coffee filter over the inlet acorn. It will help cut down on the silt your filter sucks up and will increase your filter's life.

Hope that helps a little.

Good Grief... Will Nico ever shut up? LOL

The "clearer" the water is before you filter it, the longer your filter will last simply because your not clogging it up with sediment. This of course does not mean you should exceed the filters recommended capacity, just that you can probably make it to that rating rather than having to switch the filter out early.

I also carry coffee filters to prescreen water for sediment when neccessary.

I own a Katadyn & MSR filter so I can't speak from experience, but according to their website:

General Ecology water purifiers utilize our unique, proprietary "Structured Matrix" chemical-free technology to offer the highest level of water purification instantly without chemicals, pretreatment, double pumping or hold time. General Ecology's water purifiers remove viruses, bacteria, and protozoa, plus many organic and inorganic chemical and aesthetic contaminants at the highest "purification" micron level (0.4 microns absolute) to provide great tasting water while protecting against water related disease. First Need Deluxe Water Purifiers like all General Ecology Water Purifiers are certified to meet EPA Microbiological Purification Standard against cysts, bacteria AND virus!




I'll be the first to agree that you can't believe everything you read but this might warrant a little more research...

I agree that it is VERY confusing. Even when there are resources out there that are supposed to help clarify things, even those seem to be confusing. For example there is a site out there that is some kind of independent Army comparison of water cleaning systems. They rate some stuff good and other stuff bad based not upon their studies (as something like Consumer Reports would do), but based upon reading other peoples' studies whose controls/techniques are essentially unknown.

From what I can tell the two real nasties are giardia (as you mention) and cryptosporidium, both of which come from critters' (human and others) fecal matter getting into the water sources.

Both are protozoa - one celled critters. As I understand, the adult critters can be filtered from water, but they produce oocysts (like an egg or spore) that are only filtered out by very very fine filters. These are supposedly very resistant to chemicals such as iodine and chlorine. In relative terms, crypto is MUCH more resistant than giardia. They are so resistant to filtering and chemicals most say the only real way to be sure to remove risk is by boiling water.

I suppose there are some ultra-fine filters out there that can remove even the crypto oocysts, but I would think these would plug up very fast.

Though even chlorine doesn't kill giardia & crypto, they say chlorine dioxide (micropur tablets) will kill the oocysts, but only if enough contact time is allowed. The problem is that water temperature has a lot to do with that contact time, so colder water takes longer (up to 4 hours for crypto & 30 mintues for giardia) than warmer water.

The other little battle out there is whether the MIOX "mixed-oxidant" solution sufficiently kills crypto. I'm not sure how it compares to Micropur tablets. Clearly this stuff is much better than chlorine. The suggestion is that they are about the same, but nothing I've read clarifies this for me.

So, that gets me to wondering how much of a problem these nasties are out in the waters people might be trying to drink from. I haven't found a good source with advice on how to know what the risks are. As far as I can tell the risk is always there - just about anywhere, but some areas are much worse than others.

BTW, based upon what I've read, I ended up buying a MIOX and four 4L (1 gallon) Platypus water tanks for my BOB. The MIOX can easily treat many liters at a time. This should allow me to keep enough water in treatment for my family. If the water is really yucky (lots of suspended particulates) I can try to filter it first using a bandanna, clothing, or whatever. I do not EDC water treatment.

That's a neat trick I wonder how they do it?

Their specs say
Particle Retention (microns)
.1 nominal
.4 absolute

Norovirus the food/water born virus that keeps hitting the cruise lines is
27-35 nm

The math just isn't adding up
.1 microns is 0.0000001m
35 nm is 0.000000035m

If you guys know how it works let me know because I have some serious doubts as to it removing viruses...

Just curious, but could you run salt water (ocean/sea) into the filters and be able to drink it? What about treat it chemically with mp1 tabs?

To be honest I've never looked in to it, so this is my best guess (given I'm pretty sure the sodium particles in saltwater are much smaller than a micro filter can handle). But I could be wrong.

I am pretty sure your average water micro filter would just give you clean salt water. I don't think MP1 tabs would work either at removing salt to allowing you to drink saltwater.