distilling salt water

i do a lot of kayak/canoe destination camping.
paddle several miles, land. create an outpost for a few days.
one of the limits we face is fresh water.

i can haul enough for a day or so but a longer stay is tough due to water.

anyone know of a small distiller that i could take and power for a day or so with a small campfire to gain several liters of fresh water?

a solar distiller's output is measured in cups per day. that ain't gonna cut it. but with more heat from a fire...

any suggestions?

Stills aren't hard to make but I'm trying to picture a huge pot that will fit in your yak. None of my ocean boats have bulkhead big enough to hold a 2-3 gallon pot and thats what you'll need to make it worth while. You'll also need a chiller coil of copper tubing, the longer the better, and a hood over your pot to connect the coil. You'll get way more than "cups per day" but it's work. Coil stores in your pot when traveling.
You might check out reverse osmosis filters. Expensive but smaller.

those are certainly some of the issues but i don't necessarily need a rigid pot to boil water as a water proof bag of some sort would suffice and perhaps a chiller coil of something lighter and more flexible than copper is possible.
i was just wondering if someone has already skinned that one out.

i've looked at some "life raft" filters but those assume you have nothing better to do than hang around the raft and pump a lever all day.
i'd druther go walk the beach.

perhaps i've just found a niche....

At 273 calories per gram (cc) you'll need a good volume of fuel available. There's a reason why distillation is not used by the thirsty areas of the world that border the oceans.

If there's unlimited driftwood on your beaches, you're probably good for that concern.

I'd bite the bullet and get a Katadyn RO pump unit. Neither light nor cheap, but it will get the job done and should be quite reliable.

Katadyn survivor

Cheers,

don't really want to drop a thousand dollars on an RO filter if i can avoid it.
and i do have the "unlimited" driftwood scenario so i have a heat source.
i'll keep looking...

I suppose you could try a waterproof bag and lighter material than copper but, having built a still or two (science projects), I can tell you that:
1) the more efficient your cooling and vapor collection, the less fuel you'll use. An old pressure cooker would work.
2) copper tubing can be bought at Home Depot, one box is enough....aluminum tubing can't, and plastic doesn't conduct well. A chiller bath helps.
3) it needs to be heavy duty! You'll be messing with it all day. Use a wood stove maybe? Imagine how long it takes to boil down a gallon of water on your home stove a you'll get my drift. You won't capture but half of that gallon if you are lucky.
4) Stills blow up. A waterproof bag needs to have a constant relief valve. A pan and lid have one built in (lid leaks).
I know you can boil water in a paper bag, but eventually that bag wears out, as would a dry bag or whatever you are thinking of.

As a yaker, I could likely fit a 1 gal. aluminum pot in my rear hatch with a lid and coil nested....but I'd sure get the system perfected in my back yard before depending on it.


If you pursue this idea, I'd like to know how it turns out. If you have a beach fire going all day....and we yakers that sometimes....it might as well be doing some work.

For my senior project we made a man powered water distiller. Our requirements were that we couldn't use a filter, or an external power source (fire, batteries, sun, etc). We actually made one that worked, and learned a whole lot.

Anyways, you have to prioritize. What is more important to you, and what is your budget? If you are good at working with metal, then make one yourself. It is pretty easy. I don't think there is an off the shelf unit that uses a fire (I haven't looked). An RO filter is expensive, but is also small, light, and you can get it off the shelf.

All I'll add is there's a big difference between a survival situation and expanding one's outdoor travel envelope. Anybody who does small craft ocean touring should have some knowledge of how to distill small amounts of freshwater to enhance survival chances if things go "pear shaped." And small amounts is what you'll get from simple stills.

This is quite different from extending the number of days one can travel without resupply. I budget a gallon per day per person for routine backcountry hiking and camping, half that if dry camping and lugging my water a distance.

Happy experimenting.

When you come up with something and test your model out, you can use conductivity as a general measurement of how pure your water is. Easy to measure, and once ppm dissolved solids is measured also easy to correlate. To shrink your design, you need some sort of forced condenser section; a section to condense the water after you have boiled it off. In chemistry, you run water through a piece of glassware to cool it. I think a solar still is much more efficient in terms of getting purer water (evaporation vs boiling). You may find how drinkable your water is depends upon your design. You may be stuck with running the water through twice to end up with drinkable water.

this is merely expanding the envelope. no life threatening situations will be encountered over a lack of fresh water.
the issue is the amount of fresh water i can haul in a yak when camping on deserted (in both senses of the word) barrier islands on the atlantic coast of georgia.
with the canoe, water is not an issue but the yak gives me greater range and the ability to counter adverse winds, waves and tides much easier than the canoe does and the yak offers access to areas where the power boat can't go due to surf in the anchorage.
there is, for all practical purposes, an unlimited amount of driftwood on the beaches so a fuel source is not an issue. we often burn a small fire all day as a bug repellent - skeeters and no-see-ums can be quite agressive here. a fresh water yield seems a natural companion to the fuel use.
solar distillation setups seem to require a large area, produces low yields and i'm not wild about digging up what little flora anchors the non-tidal shoreline in order to produce water.
there's lots of beach at low tide but every 6.5 hours, there is an 8 ft swing in water level so what's bare at 8am has up to 8 feet of water over it at 2:30pm and bare again at 9pm.
could be only 6.5 feet or up to 10 feet depending on astrological scenarios but could be more or less depending on wind direction.
reverse osmosis bankrupts the budget - not to mention the sheer monotony of pumping for hours on end for the yield of a few liters.
i have a 3 liter pot that fits in the hatch for which i could add an outlet to the lid. perhaps i could get a bigger pot but backyard experimentation will be necessary to ascertain the yield.
sure seems that someone would have already solved that problem: ~3 liters a day, small fire all day (and part of the night).
i'll keep looking.
if someone has a better idea (i.e. a better solar solution - i'm in the deep south so sun light is not an issue - complexity of the setup could be), i'm willing to listen.

Google "stove top still" and look at what pops up. I did this earlier today. One link was for water purification and they were quite proud of "1.5 quarts in 2.5 hours". So, in about 8 hours of steady fire tending, you'd get a gallon.
Lots of these little stills use water jacket cooled coils. A motorcycle radiator might do the trick for portability, as a condenser.
Now you got me interested. I paddle a Hurricane Tracer which is low volume in the holds, so it needs to be a really compact setup.

A little while I played with a simple still using only things I'd have in my backpack. It uses the following:

Tin foil
pot
tube from a hydration bladder.

It's slow, but it works.