Just about any of them will do. And, just about all of them have their up and down sides.


I've got three different ones. One is a Katadyn pocket. Nice, but heavy, it stays in the truck. I never pack it.

I live and hike in a four season enviroment, and have come to the conclusion that no one method is the best. Filters freeze in the winter, better have a backup plan.

this is my water fliter selection in my BOB.. I think i paid $60-80 for the hand filter.


J

The effectiveness of a filter depends on the water quality to be filtered.  Most of the filters on the market are intended for either home or hiking use which is pretty much a decent water quality to start with.

In this case, I often recommend the MSR Minworks though I admit its a personal preference and about any work fine.

From a survival standpoint where one can not always predict the beginning water quality, I recommend the First Need which is virus (non-chemical treatment) and chemical rated.

Most questionable water is slow moving water downstream of industry/cities or farm field runoffs.

Tj

Quoted: From what I read on the above link, it appears that the MSR Sweetwater has the best coverage. Am I reading that right? Anyone know anything about this unit? Weight, size?

You still add chemicals just not iodine.

I repeat again only The First Need is EPA rated for filtering virus as well as an activated charcoal base for chemical treatment.

There's many ways to skin a cat and it really depends on your starting water.  A nice mountain stream, a hand squeeze filter does an excellent job.  A slow moving river running by a major city or a slow moving creeks surrounded by pesticide farm crops is a different story.

Does the Sweetwater do a good job?  Yes, as long as you don't run out of chemical.  It has a shortcoming just like The First Need does in the fact eventually you will have to replace the fliter.  

Tj

Quoted: So, would a layered process like straining, boiling, then filtering through one of the better units, be a more comprehensive method? Is there a pre-filtering method that anyone uses along with boiling that enhances the performance of the filtration unit by not stressing it as much with straight from the pond water? I'm speaking of this in conjunction with a non-chemical filtration device. It just seems that anything done to remove the obvious large particulate matter first, would be of some benefit before pouring it into the filtration unit. It's not like there are many pristine clear running water sources in my neck of the woods. It's mostly murky, fairly stagnant water that's found around here. Obviously, I haven't had any experience with any of these units mentioned, so I have a steep learning curve here.

There's a number of methods for prefiltering before you use your main filter that help.

Some people like filtering through cloth to get the larger suspeneded solids out prior to filtering.  Some filters have screens which vary from metal mesh to silk.  The basic idea is limit clogging.  

For stagnant ponds or slow moving creeks, I personally like digging a hole directly beside the water.  Allow the hole to fill through the soil and sediment settle, then filter.  This works much like a well by using the ground as a sand filter/Earth filter. How long it takes is dependent on the soil quality.  Sand is pretty fast, however soil can be quite slow to settle and often you have to skim off the floating material.

In stagnant or slow moving water, always try to take your water from just below the surface.  The heavier suspended solids tend to drop with time.  In swamps, you will often notice a few inches of what looks like somewhat clear water then a few inches of murky water.  Many filters have floats on their intake lines to help with this.  

None of these methods eliviate treating for micro-organisms/germs but will increase you filter life or slow the clogging process.  Please keep in mind that there is no universal rating for water quality for determining manufacturers filter lifes.  How they work varies all over the place depending on water quality.  The trend the last few years has been to become much more conservative with these figures.  They sell more filters this way.  

Many of the filters rated for 125 gallons for example just two years ago were rated for 400 gallons and really in clear mountain water would do ten times that.  You have to use your own good judgement.

A couple miscelaneous things is typically activated charcoal after being wet is considered to have a life of six months regardless of the amount of water it did not see.  Ceramic filters loosen up a little on pour size with each cleaning.  

Now we'll talk micro-organisms a bit.  Most filters are 0.02 microns nominal.  For all practical purposes that means they will filter gram negative rods (fecal bacteria) and parasites pretty good on their own.  Gram positive cocci like strep or staph they won't filter as well.  Virus they won't at all.  Now for a bit of good news, virus has a very short lifespan out of its normal enviroment which is organic matter and temps close to body temperature.  I use approximately 60 degrees as my rule of thumb.

What that means for most water sources that do not have human habitation upstream or a dead animal, the filter will work fine without secondary treatment.

Boiling is still a very effective way to kill germs/parasites in water.  The general rule of thumb is 1 minute for every 1,000 ft of altitude.  Though definately not as high tech as the MSR Miox or Steri-pen, its actually faster and just as effective.  

The limitation of chemical treatments such as iodine is once you are out, you're back to boiling.  They're advantage of course is you can treat and continue walking/working etc. till the treatment period is done.  

Chemical after treatments work, however how long or how much varies by brand so you need to follow the directions on the bottles.

An interesting recent study on food poisoning showed that diners who drank a couple classes of wine/beer while eating had a 50% rate of not being impacted while a startling 100% did not who were drinking hard liquer.  Could explain the old axiom of drinking tequila whle eating in Mexico.  

What it does for this discussion is point out, that being exposed one germ won't necessarily cause a disease.  Its all a matter of odds and numbers.  The greater the number of contaiminents the higher the odds of infection.  

No filter system or purification system is perfect with probably boiling coming the closest but the vast majority do a good enough job to keep the average person healthy.

Tj  

Quoted: Would be a good tack for survival forum. Get some good info and keep it around.

Yes, I'm actually working on a FAQ for the content files regarding water.  Its just taking a while since to cover everything, its quite long and an ardious task.

Basically, I am a CheE who started out his life in water treatment after a heavy dose of microbiology in the service and a minor in college.  Through this forum and the various camps I have attended, I had the opportunity to see many of the filters on the market in action.  

I guess that's one reason I'm not quite as bias as to brand preference.  I've seen the $30 hand filters work in water I knew for a fact was contaiminated (one of the guys who didn't filter actually got sick and had to be treated) right along side the $200 Katydne.  

I do stress and the best place to begin in filtering water it is always best to take your best shot at what you think the water quality is.  Pesticide or asphault runoff for example will have chemicals in the water just like being downstream from a carpet mill will.  I've seen sewage plants put out water you could drink but I've seen those same plants be over taxed due to influent dumping stuff I wouldn't even wade in.  Fast moving water over rock acts a natural water treatment while stagnant water with decaying organic matter a natural breeding ground for micro-organisms.  

One of the tools I use is Mapquest (aerial view) and Topozone which will show human habitation in relation to water sources.  Those topographical maps you use whle hiking have far more uses than just getting from point A to point B such as a good idea what is upstream of your water source.  

Its good to keep basic geography in mind.  Over the years the heavy metals on this planet have sank.  This all means in area where the Earth has been disturbed say a strip mine or mining area, the odds are higher for heavy metals.

As you can see there is alot to this topic and of course the ultimate question is what do you do when the filter works no more?

Tj