Brenjen

I bought one of these last year & I recommend it to anyone who walks away from their vehicle in the wilderness. As we all know (or should know) water is the #1 thing you need in a survival situation & next to hypothermia, dehydration is the main cause of death when people get cut off from their transportation unexpectedly. Of course there are people who take medication or have medical ailments that would supersede the water requirement but for otherwise healthy people who aren't injured water is key to staying alive long enough for rescuers to find you or for you to extricate yourself.

This device is about the size of a mini-mag light & works w/ batteries & regular old rock salt & a cap full of water. It creates an electric current through the salt water which in turn makes chlorine (for all intents & purposes). Add that mixture to dirty water & presto, potable water. If the water you treat is already fairly clean or if you make too strong of a mix, your water will taste like chlorine but with practice & knowing the water source you can get it drinkable w/o the chemical taste & even at that, the taste is better than iodine tablets if you've ever used those you'll know what I mean.

MIOX by Mountain Safety Reasearch

Mattabilly

I used to sell those at a gear store. They are very cool. The only thing I caution people about is depending on the water you do have to let it sit for a recomended amount of time for purification to be complete. But like Brenjen said super small and also used by the Armed Forces in remote areas.

revoltdeceased

just to throw my 2 cents in here. it doesnt actually make chlorine, thats now what the oxidation reaction is all about. it creates hypochlorite ion, HClO-, and the sodium ion Na+. this is essentially bleach. NaClO, sodium hypochlorite. it really just seems like an expensive (80$) bottle of bleach. i guess its convenient in a third world country where you cant find bleach but can find salt. it converts salt, through electroloysis, into bleach. chlorine will kill a lot of bacteria, but not as much as bleach. not much of anything can survive the basic environment of bleach, microbiologists will speak wonders of how they bleach everything because it will kill all. the bad thing about the MIOX purifier is that it is battery operated. so you cant just leave it in your truck for months/years. i would recommend a ceramic filter from MSR, becuase you can leave it in your truck for months/years and it will still work. i would also bring an eye dropper of bleach as a backup. one drop will go a long way. over time the bleach will lose its effectiveness, but you can always grab an ounce from under your sink and use it. just make sure that it is pure bleach and absent of any additives. .... i'm no expert but i am a micro, bio, and chem student, an avid backpacker, and did some research on this when i was purchasing my water purifier/filter for backpacking.