I went camping two weeks ago and used my Katadyn Pocket extensively to filter brown creek water for me and my buddies.  It worked awesomely, no one got sick, water tasted like tap water.

The creek had some current to it, no skim on the surface, however, there was a beaver pond about 1/2 mile up the creek with a skim on the surface, and the bass we caught out of it were wormy.
Would that water be safe to drink only filtered?

I am very unsure about when filtering ONLY is okay and when water needs to be purified as well.

I really wish companies would keep the two terms separate...but they seem to freely interchange them at times.

Here's what I would say is important...but do your own research, because I could be a crazy person:

The filtering part is what catches things like cysts, bacteria, parasites, and protozoa.  Manufacturers usually give you a micron rating for the filter's pores, and anything bigger than that is not getting in.  Having the ability to "filter" your water to remove these afformentioned polutants, is a huge step toward not getting ill.

However, there are also Viruses, and chemicals that are NOT stopped by the small pores of the filter.

That's when things get fuzzy for me.  Some of the filters have active carbon in their cores, which also reduces the chemicals in your water...but they are still not officially called "purifiers".  Some filter manufacturers sell post-filters you attach downstream of your existing filters, again, for the purpose of removing chemicals.  I guess you're officially entering "purifying" territory when you know you're getting the Lead, Flouride, MTBE, etc out of your water.  That's BEYOND filtering in my opinion.

BUT (and it's a big one), I've not seen any filters, or post-filters, claiming that they stop/kill viruses.  Silver in the Filters will stop bacteria from growing into your filter, but does not kill all viruses passing through.

Viruses are not all that common out in the woods, depending on your area....but in the event humanity begins to add its own waste to the locale (aka garbage or sewer down), they (viruses) could quickly be found in the water supply.  That's a big deal...when you think of H1N1, Hepatitis, HIV, etc.

Viruses are killed by chlorine, and even iodine.

I've read recommendations that say if you can't boil your water, pre-filter it with coffee filters into a "raw water" container just for that purpose, add the chlorine, and let it stew until it kills the bugs.  THEN run it through your filter, to catch any chlorine-resistant spores or cysts.  If you have active carbon in your filter, you might very well remove your own pre-treat chlorine from your final water, which is good because long-term chugging of chlorine can't be all that good for you.



Much of this is not really field-expedient, unless you like to backpack with a bucket and a Big Berkey.  So, in that case, perhaps consider adding some of Katadyn's Micropur tablets to your gear, if you feel viruses are a possible threat.

That clears it up for me. Thanks!

Glad to help.  Perhaps you could explain this sentence of yours to me?  I was thinking about learning to fish, and I'd love to know what "wormy" means to me, as the guy who's planning to eat the fish.  

Worms can get into the meat of the fish.  Hold the fillets up to light, look for them in the flesh and in the fins/tails.  It's a parasite. I think it is okay to eat fish with worms if cooked well, but for me it's nasty.
I'm not really sure what causes them, if it is stagnant water they thrive in, but I think the bass are more susceptible to them later in the summer.

Hope that helps.

Eewwww...

Right!  Vegetarian it is!



Thanks for the info.

Ideally you will have a filter that is ceramic element or a "paper" element with a carbon block core or a carbon element inside.  Carbon takes care of the chemicals, taste and smell........  .2 micron ceramic/"paper" elements takes out all the other junk.  If it's questionable, add iodine or chem tabs then filter it, especially of you have carbon, that will take the iodine taste out etc.

PUR used to make a "purifier"  (a filter that does it ALL) they realized it was not truly purifying the water and stopped making the iodine-matrix filters.  Those went bad after a few years of storage anyhow.

The MSR Miniworks or Waterworks, are a combo element and Katadyn has one or 2 also.  The MSR you can thread on to a Nalgene bottle or dromedary bag and they have a good flow rate.  Some of the small ceramic filters are a PITA if you want to get a few gallons.   The upside to ceramic over "paper" is you get more gallons out of the filter before you need to replace it.

Hope this helps.

Oh and Iodine  alone does not kill cyst's!!!!  That is why I go with Katadyn Micropur tablets.

It seems like you could simply make your own saturated Iodine solution by simply keeping some Iodine crystals around to place into a small bottle with water when needed. You could then use a few drops of this to treat water. The crystals should last a lot longer if stored properly. Some potential problems include improper storage can lead to Iodine gas which is deadly in an enclosed space, and anyone with Thyroid problems can have an exacerbation when they ingest this stuff depending on the problem. Seems like a useful tool provided you know it's limitations. This could also give you an Iodine source in case of nuclear warhead detonation or nuclear plant meltdown (but not needed for a dirty bomb) to help protect your thyroid.

Activated carbon is for odor and taste only, it does not remove harmful chemicals. If your water is chemically contaminated look elsewhere.



Do you need to remove or kill 100% of waterborne pathogens? Absolutely not. You just need to remove the dangerous bugs and only enough to keep from getting sick.

Viruses? What viruses are you looking to remove? Two of the most "common" viruses are the Norwalk virus and Hep B. Even then they are very rare, the Norwalk virus is mainly found in groundwater, esp wells but even then the rate of illness is very very low. For me not enough to be concerned about. As to the later, I am vaccinated, plus the rate of infection again is very very low. Basically you would have to have the worst luck in the world to get a virus, but then again when it rains it pours.

Viruses tend to be very unstable, a bit of sunlight exposure and/or a bit of chem treatment will take care of that.


The most popular filter size is 0.3 microns. Personally I use 0.2 microns.

Again you do not need to remove 100%, just enough to not get sick. You consume far more pathogenic microbes than you can ever imagine, just usually in low enough numbers so that they cannot establish a colony. Either being killed, crowded out, or immobilized by your normal flora or being destroyed by your WBCs.

Not all filtered water needs a chemical treatment but all chemically treated water needs to be filtered.

To expand upon this since I cannot sleep.

Activated carbon is not charcoal nor can it be made at home in case anyone is wondering.

Activated carbon only removes a percentage of the chemicals that it can remove. Even then those chemicals it can remove, it typically only removes enough of it so that you cannot smell or taste the chemical, thats it. It does not remove many of the pesticides, petroleum byproducts, and other nasties that we have grown to love. In short, do not think an AC filter will make chemically contaminated water safe, it was not intended nor can it serve that function.


Another thing is "water purifier." As far as I am concerned that term is garbage. There is not a man portable water filter known to man that will remove "100%" of anything biological (unless the claim is 100% removal of sticks, beavers, and hippies), hell I am not aware of anything in a lab that will remove 100% of biologicals. Typically the process of "purifying water" includes running water through a series of reverse osmosis filters time and time and time again until the % of contaminates is within a desired level. If the claims of the product are too good to be true then typically they are. Unless someone can show me a "water purifier" that has been independently tested by a certified lab (and no UOP labs do not count) and has been EPA certified as being "purified water" then my opinion will stand.

Be aware of "meets EPA guidelines" vs EPA certified, there is a difference.

The micron level can be tricky too depending upon the testing method. Terms like absolute and nominal come to mind. Is the pore size 0.2 at the smallest or 0.2 at the largest, big difference. Filters are like sponges, there are big holes and little holes. Some filters will claim a micron size if their average pore size is a certain size, some will claim a micron level if their largest pore size is a certain size. Big differences here.

Now you may be saying, " OMG! It doesn't remove 100%!!! But I will get sick!" Well settle down and think about the percentages. Different bugs require different numbers to make you sick. Lets say bug A needs 1,000 bugs to make you sick while bug B needs 10,000,000 to make you sick. Well you need to make sure that the filter is removing enough to bring the threshold  down below the minimal numbers needed to make you sick. Cysts and parasites only need a relatively small amount of bugs to make you sick but thankfully they tend to be fairly large so even mediocre filters tend to take care of them while the smaller bugs tend to need far more to make you sick.

BTW cysts tend to be resilient little critters, not all chemicals are effective against them and UV light tends to need a fairly long time to kill them.

Now why did I say not all filtered water needs chem treatment while all chem treated water needs to be filtered? Filters remove the particles out of the water right? Well if you don't remove those particles they can act as little shields and fox holes to protect the bugs against the chemicals and/or UV light. Your chlorine can't kill a bug that is gift wrapped in a dog doo particle can it? You want to filter the water to remove all the particles out of the water leaving only the biologicals, then you treat with chemicals or UV. And no a coffee filter or Tshirt will not work, we're talking filtration around the 5 micron size at least to remove particles.

Personally I use the Katadyn Hyperflow and the Katadyn Hiker Pro, they work well and offer many benefits. 0.2 micron and 0.3 micron respectively.


Now on to the single most important point of advice. We all hear the stories about, "Well I used this filter and I did not get sick but all my buddies got sick using their different brand filter." You know what most likely is the reason behind 99.99% of outdoors GI illness when using a water filter is? Cross contamination.

Your dirty filthy hands (which I know you did not wash after you pooped and wiped your ass with tree bark) are now handling your Nalgene water bottle and water filter. Did you make sure that none of the untreated water did not make it into your bottle? Did you make sure to store the "clean" tubing in a separate bag from the "dirty" tubing? When was the last time you washed that water bottle, if at all? You have to think about dirty vs clean. Your dirty hands touched the water bottle cap right? Now when your hands open the cap they are now contaminated, did I see you just grab a protein bar and eat it after you opened the water bottle to quench your thirst? Did you clean your hands after getting them all wet with dirty water when filtering?

Hygiene should not stay in town with the "city folks" less you wish to be sick. How many of us wash or sanitize after we piss on a bush or squirrel while camping/hiking? Did your buddies wash their hands? If not then their penis/ass germs are now getting all over your gear, gear which you will undoubtedly touch with your hands, hands which will certainly touch your face or be used to put items in your mouth. Now you have penis/ass germs in your mouth, congratulations.

No point in cleaning water if you are only going to recontaminate it or put your or your buddies penis/ass germs in your mouth.

MrHunterAZ: good point. The thing is prevent cross-contamination of clean pre-filter and filter equipment.

I was told if you are mostly in the US or Canada, you only need water filter(filters out bacteria); now if you're in a 3rd world country, where there is the ebola virus etc then get water purification(deactivates viruses).

Now if you were in a SHtF, then I would go with US EPA certified water purification.

Good post, thanks.