The problem with boiling is that you can't keep moving while you do it...same with a bulky filter. That's the one thing I really love about the MIOX pen. I can fill my canteen anywhere, treat it in 20 seconds and keep walking while I wait for the solution to do it's thing.

If I'm camped I won't even bring it out as it's just a waste...way easier to boil then.

"No filter makes sense unless it also removes viruses, because you still have to chemically treat it, or boil it to kill them. So why not just do that in the first place?
The Sock"

IMO, pending more information, viruses aren't really much of a problem as long as humans aren't present. Of course finding an area not traveled by humans is another issue entirely. The wilderness is getting smaller every day and what wilderness there is is increasingly less wild than it used to be.

That said even when humans are doing their thing in the water it is fairly rare for anyone to get infected by otherwise well filtered water. The threat is far more theoretical than actual IMO. People infected usually have been exposed to water that was not filtered. The reason being that viruses are pretty fragile out on their own and so they tend to travel contained in or attached to other materials that are easily removed from water by even a basic filter.

This is related to the old argument over using condoms. Claim is that the pores in a latex condom are larger than the size of an AIDS virus so condoms are useless. But studies of those who use condoms consistently show that condoms stops the transmission of AIDS.

Reason being that the virus doesn't travel out on its own. it attaches to other materials and rides. Stop the transmission of these much larger biological materials and you stop the virus.

PS. - All that said I usually carry a treatment that is good against viruses for those cases where I suspect that the load of infectious diseases in the water are likely high.

Traveling in the remote swamps or the SE well away from populations and in areas seldom traveled by hikers or hunters I feel pretty confident in just filtering the water.

In a case where the water is likely contaminated by sewage, like the flooding seen in NOLA, I would use a treatment that pounds on viruses.

Of course in that the water also has oil, pesticides, other toxic chemicals along with raw sewage and every other possible contaminate so I would use every method I could reasonably manage.

Art_in_FL, I have to respectfully disagree. Because even if there are no humans around, there are animals around doing their thing. And that can make you sick, which is not a good thing anywhere, but especially out in the "wilderness".

I'd rather not risk it. Treating water (no mater what the means) is not so big a hardship.

I used to believe that. If I couldn't boil, I would drop in an iodine tab. Or not, if I was feeling lazy.

Sucking down water with agchem run off in it changed my opinion (and helped me loose ten pounds in two days ). Carbon filters are your friend.

With the steri-pen, be aware that batteries go fast in cold weather. Carry spares and (you probably already do) carry a back up (chemical or filter).

With any chemical treatment that I know about, in cold water you'll need to let the water stand for quite a bit longer than the instructions say.

Another item of note is that iodine, probably the most popular chemical treatment for outdoorsmen in N America, really does not do a good job on cryptosporidium although it does work well on girardia. Crypto isn't very common, so iodine may still be an appropriate choice, but something to be aware of.

One further thought: boiling is darned effective and will kill off a lot of things that might well survive iodine, but you do have to be able to make fire AND have enough fuel available. If you like higher altitudes (9000+), you have to hump liquid fuel -- wood except in an emergency isn't an appropriate choice at higher altitudes due to slow growth rates and fragile montane/alpine eco systems. Liquid fuel weighs a fair amount, which makes one of those little vials of iodine tabs ever so attractive.

I had very good experience with the MSR MIOX. Twice using it the fields and I did not suffer any ill effects.

I even use the MIOX at campsite to treat water in big container before I using the water for showering. Try treating your bath water with other methods such as steri pen, tablet, etc. is not very feasible.

Recently, I am using the MIOX when I stay at hotels in 3rd world countries. Although some hotel do provide electric kettle in room. But the kettle is usually very dirty. So what I do is before I go to bed, I would fill up a platyus 2 litre bag with tap water and treated it with the MIOX. I will leave the bag overnight and next morning I will have a 2 litre of treated water for drinking.

Here's an interesting link to a posting about filters on the CDC site:

http://www.cdc.gov/ncidod/dpd/parasites/cryptosporidiosis/factsht_crypto_prevent_water.htm

In the posting it says:
Filters labeled only with these words may NOT be designed to remove crypto

One of the items listed is:
Ultraviolet light

Am I reading that correctly? UV does not kill cryptosporidium? Crypto is relatively rare in the contiguous states, Canada, and Alaska, but not necessarily elsewhere. If I'm reading this correctly, a Steripen would be a poor choice for international travel.

Steripen's website says:
SteriPEN™ is the only portable water purifier that uses ultraviolet (UV) light to destroy waterborne microbes. Whether your source is a woodland brook or an overseas hotel tap, SteriPEN purifies clear water by destroying viruses, bacteria and protozoa—including Giardia and Cryptosporidium —- in seconds. Carry a SteriPEN to disinfect water wherever you travel, hike, camp or trek. It’s the fastest route to pure, safe drinking water anywhere.

Somebody's got to be off here.

If you look on the Steripen website, they link to a scientific article which compares various purification methods against crypto. The Steripen does very well in this experiment versus the chemical methods. The Steripen does just as well as heating (I guess that means boiling). As long as the water is not turbid, the Steripen seems effective.

"May not be designed for..." is not quite the same meaning as "does not work against...".

Well, that's just one study. I haven't tried finding any others that substantiate that claim.