Water purification with campfire still

Joined
Nov 28, 1999
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12
There has been ample discussion on how long to boil water, with opinions ranging from one minute to twenty. (Please excuse me if I've left anyone out!>) It has also been pointed out that prions (the infectious agent in Mad Cow Disease and probably its human counterparts) are not hurt by boiling, though they are probably still trapped in the British Isles. So if you want to be more careful, you should filter your water. And if you REALLY want to be careful, you should distill it.

Distillation leaves almost everything behind, except volatile chemicals such as alcohol (and other "aromatics" fondly regarded by drinkers of whiskey). There are solar stills, which usually involve some sort of plastic sheet. But if you have no plastic sheeting, or you are interested in a higher volume of water than can be produced by a solar still (perhaps you are trapped on a rock in the Aleutians in a dry winter), then you, like me, would be interested in a saltwater still.

A saltwater still is, in principle, nothing more than a kettle (or a billy can with a tightly fitting lid, and a hole in that lid) where the fresh water steam generated by boiling salt water over a fire comes out a tube, and is cooled to turn the steam back into water. A kettle with a plastic tube (made out of a plastic that can withstand the temperature of boiling water) is probably sufficient. Just run coils of the plastic tube down into and out of a nearby handy pot of cold saltwater. The plastic is not a terrific heat conductor, but it will probably cool the steam enough to cause the steam to condense on the insides of the tube, and as more steam keeps coming from the kettle, the water will be pushed out the end of the tube, into a waiting can. Presto chango, distilled water.

It would be MUCH nicer to use a system where a metal tube coiled inside the cold saltwater condensing pan. And it would be nicer still (punintentional) if the metal tube were soldered to the outside of the condensing pan, so that the coil could exit lower than the entrance, and so not require the steam pressure from the kettle to push the condensed water up over the height of the edge of the condensing pan. And it would be downright terrific if someone SOLD a kit to convert a camp kettle into a saltwater still, with the condenser all ready and a flexible tube tip to join with the kettle.

The problem is... the "saltwater" still makes a perfectly serviceable "moonshine" still, and various government entities know this. So if you open your favorite camping gear catalog, you're not going to see a still kit, saltwater or otherwise. And if you get enterprising enough to offer it to the public yourself, the folks who sell those tax stamps that cover the tops of the hooch we buy at the local store will be paying you a friendly visit. Even if you and all your customers swear they're only using it for turning saltwater (or free range water) into fresh. Which isn't to say you shouldn't do it anyway and sell one to me!

So... anybody out there have experience with making camp stills? Know what types of easily obtained plastic will work with steam? Is there come part of a car's air conditioning system I should know about? Ever made a camp still out of available natural materials? Anybody know of a hollow vine that could be used in place of a plastic or metal tube (that wouldn't leach out some vile poisonous sap into the otherwise pristine distillate)? Inquiring minds might want to know. I know I do.
 
The only fire fed still I have ever been around while in operation had pure alcohol running out of a 1/4" diameter piece of stainless steel tubing, a thumper keg, and used bread dough to seal the top of the still to the tank. The finished distilled product was crystal clear liquid, bubbled good when you shook it, and smelled like good tequila (if there is such a thing).

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Randall's Adventure & Training
jeff@jungletraining.com

 
As I suspected, possibly partly due to the unavailability of commercial campfire still equipment, the only experience anyone has with it is in its alcohol purification guise.

After further thought, I think it might be possible to use boiled (cleaned and sterilized) animal intestine to transport steam from a kettle through a cold saltwater condensing bath in a wilderness survival situation.

-Mike
 
Mike,
I recently bought a backpack pressure cooker which turned out to be an excellent investment--works so good w/dried beans, rice, etc. that we are going to pick up a larger model for home use. But, I digress. Among it's other uses, the pressure cooker can be used as part of the still you described. Attached is an interesting site which I think may provide you with the other components you are looking for. http://www.naturalpurewater.com/life_saver_distiller.htm
Good Luck,
Nahbi
 
Hi Mike,

Distillation is clearly the way to go but then common, good quality, filters are successful and much easier to use than distillation.

We have used a transpiration bag in the wilderness to clean water. During the drought the water was so low and mucky I had the students set up bags every day to make nasty stuff drinkable and it worked very well.

As to the Prions. "Prion protein genes have been identified in a number of mammalian species including human, monkey, hamster, mouse, rat, mink and cattle (reviewed by Oesch et al., 1991; Goldmann, 1993; Schätzl et al., 1995), as well as in chicken (Harris et al., 1991; Gabriel et al., 1992)." They are not yet prevalent but have been identified around the world. A whole gang of cannibals are dying off from a form of the disease. The disease is fairly prevalent in South America but not commonly known for what it is.

The good news.... Papain is effective as a water killer in Prion diseases. The chemical breaks down the protein fragments very quickly. Friends at the CDC tell me they have been testing the process. Where do you get Papain? Meat tenderizer.

Ron

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Nahbi & Ron -

Thanks for the info!

Nahbi, I'll look into the pressure cooker and website you recommend.

Ron, I believe it is far easier to use a filter than to attempt to make a still. I'm just curious about all the options. I especially like the note that papain breaks down prions. Go pick a papaya!

Regarding my suggestion about using animal intestine for condensing pure water in a saltwater cooling bath, there is a subtle problem. By its nature, the membrane that makes up animal intestine is a "semi-permiable membrane," which means that the pure water will be "sucked" through the membrane into the saltwater... not fast, but perhaps fast enough so that you'll lose an appreciable fraction of the distilled water. In a survival situation where you don't have a filter (but you managed to bring a pressure cooker?!!!), you'll want to switch to a fresh water cooling bath as soon as you have some fresh water to use for that purpose.

-Mike
 
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