Speaking from experience, the best method I have found is to carry your water with you, next best was distillation using fuel (a stove if you have plenty of fuel or a firewood back-up if not), although I'd be prepared to use other methods like a solar still, or pump as well. A group of us were stuck on an island in Baja and held down for 3 days by winds 35 to 40 mph winds (we measured) gusting to 55 mph. Late on the first day we realized that if these winds lasted more than three or four days we would be out of water. On the second day we spent all morning (a cooler time to minimize sweating) digging a pit for a solar still. We threw in a lot of salt water and covered it with a lightweight CLEAR plastic film (Clear not Black--Black won't work--just gets hot and won't allow the evaporating water inside the pit to condense on it). Had a pot in the bottom and even surgical tubing down into the pot so we could drink directly out of it and not have to open up the system to get the water out. We then carefully placed a large smooth stone in the middle above the pot and waited and watched. The plastic became covered with condensation, raising our hopes. Trickles started to run down the plastic, but to our chagrin most of them broke loose too soon and didn't make it into the pot. The plastic was vibrating due to the wind (and pressure changes due to gusts) even though we had built an elaborate wind break around it and not much wind reached the plastic. About 1/2 hour into our little experiment that took all morning to set up the sand that had blown into the top of the still combined with the motion of the plastic ground a hole through the plastic and the rock and gritty dust/sand collapsed into the catch pot with a sickening thud. Lesson #1: use much heavier plastic than the lightweight (1/2 mil) painters dropcloth I happened to have. Lesson number 2: You are unlikely to get this to work when the wind is up even with more durable plastic. This is unfortunate since during strong winds is the most likely the time you will be stuck somewhere on a paddling trip. Plan #2: build a moonshiner's still. Someone had a pressure cooker, we hooked it up to my surgical tubing and fired up the stove. It worked a little but not very well. We sought to improve it. I had a snorkel that fit over the pressure relief valve, We cut the long tube off another paddler's Bow float bag, it fit perfectly inside the snorkel tube and we taped the other end of that 3 to 4 foot tube into a 1.5 liter medical bottle which we stuck in a bath of sea water. We quickly heated the seawater but even when it got very hot and we soon tired of changing it every few minutes we were still making about a quart of water per hour this way and probably using less than a pint of fuel per quart. The water tasted like rubber from the hot snorkel tube but it was fresh and palatable (although we never had to use it we carried it with us until we got back to a water supply). Later I made a still from a backpackers pressure cooker and some copper plumbing tubing that I could store coiled inside the pressure cooker. I also got a Survivor 06 (the smallest of those fresh water makers under discussion here) to test out. I tried it and it worked, but slowly enough so that for all the work that went into it was quickly obvious it would be only be suitable for backup survival. It also required careful maintenance, had a limited life and needs to be returned to the factory periodically to have the membrane replaced. It was hand operated but I though it would be far better to make it foot operated so you could use your hands for other tasks like holding and turning the pages of a book during the long hour of pumping. I sent this device to Baja with others a couple of times to get there opinion over the next couple of years. The unanimous conclusion was "for survival mode only". I don't know the reason but on testing it after the last user (a long trip) it no longer functioned. I haven't bothered to get it repaired. Ed Gillet had two (I believe) of the larger hand operated ones on his California to Hawaii kayak trip. Since everything he had powered by electricity eventually failed I suspect he's glad he had the hand pump ones. There is a spherical shaped military solar still that is designed to work while floating in water but I have never seen one in operation. Graham MacIntosh described using a tea kettle as the container for a still and it was by far the best way he made water during his 3000 mile walk around the coast of Baja (described in his book "Into a Desert Place"). It almost killed him when it corroded out and became useless once when he really needed it. Hot salt water is very corrosive. I take at least a gallon a day. I store it in many containers so no one leak or accident to a container will leave me wanting. Two liter soda bottles work well. They are very tough and can be flattened to regain storage space and can be blown back up if more water is found to refill them. They are small enough to tuck into many leftover nooks and crannies between gear bags and the hull. They can be easily moved around to get a level trim too. Matt Broze http://www.marinerkayaks.com original message: Date: Tue, 01 Feb 2000 19:40:52 -0800 From: Dave Kruger <dkruger_at_pacifier.com> Subject: Re: [Paddlewise] Saltwater to Freshwater "Devices" BaysideBob wrote: > > Speaking of "survival", does anyone have any info on distilling fresh from > salt? > I saw a website of a fellow who did it at the rate of one part fuel to one > part freshwater distilled, not too effecient and no details as to how it was > done. Or perhaps solar stills? Basically, to get the efficiency up, you have to make good use of the heat from the fuel by pre-warming the water entering the still pot with some of the "waste" heat from the condensing phase. That is SOP on the oil patch or in a refinery, where every calorie of waste heat is a few millicents lost, and every food Calorie is a penny lost. A practical thing when the operation is stationary and will be used endlessly. Some arid countries do this with sea water. Invariably, they have cheap fuel -- or, as in the Middle East, the fuel is "free:" in Saudi, natural gas has no market, so they just flare it off at the well head. At that price, it pays to make fresh water from salt. For we energy-poor sea kayakers, using a large surface-area unit which exploits the (low-grade) heat from the sun, and a condensing water source of coolness (read: sea water as the condensing fluid) is the only really "efficient" and practical method. Drawback: can't be done on the rolling deck of an enroute sea kayak. Can be done ashore, with some setup time. Good to know for a survival situation. I think NOLS has published some methods using black plastic as the solar collector for the heat. A Web search should reveal some tested techniques. - -- Dave Kruger Astoria, OR chemist *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
Try www.watertanks.com for a decent list of salt water to fresh water purifiers. I just found the site this weekend and have never bought anything from them.... The filter you mention is marketed as a surival tool. There is a larger and fast filter but it was 1200-1400 USD. Very expensive. They have motor driven systems as well. Hope this helps... Dan McCarty *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
I have a couple of survival books. I can't remember the names off hand but I can dig them up if someone wants it. For drinkable water on the beach SUPPOSEDLY, you can dig a hole behind the first dune line. Any water that rises in the hole is drinkable. With a container, a cup, clear plastic and if you are really lucky a straw you can build a solar still. First dig a hole, put the cup in the hole with the straw resting in the cup and place the plastic over the hole. Try to seal the plastic to keep in the heat and humidity. The plastic should droop over the cup so the water falls into the cup after evaporating. The purpose of the straw is so that you can drink the water as it fills the cup without breaking the seal. I've have never done this. But this is not going to produce lots of water. Its enough to keep one going a bit longer. You can prime the still by adding moisture to the still. This supposedly works in the desert as well. But there the only way you can boost the still is with your body waste. Yep, thats what the book said. 8-) The desert stills work buy capturing the water left from dews overnight. Hope this helps... Dan McCarty *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
>From: dmccarty_at_us.ibm.com >I have a couple of survival books. I can't remember the names off hand but >I can dig them up if someone wants it. > >With a container, a cup, clear plastic and if you are really lucky a straw >you can build a solar still. First dig a hole, put the cup in the hole >with the straw resting in the cup and place the plastic over the hole. Try >to seal the plastic to keep in the heat and humidity. The plastic should >droop over the cup so the water falls into the cup after evaporating. The >purpose of the straw is so that you can drink the water as it fills the cup >without breaking the seal. > >I've have never done this. But this is not going to produce lots of water. >Its enough to keep one going a bit longer. You can prime the still by >adding moisture to the still. This supposedly works in the desert as well. >But there the only way you can boost the still is with your body waste. >Yep, thats what the book said. 8-) I've read suggestions that you can also strew bits of plant material on the floor of the solar still, where the heat evaporates the moisture from them. Easy enough at the sea shore; in the desert you'd propably need a matche to penetrate cactus. I also wonder if you'd sweat off more moisture hacking cactus than you'd get in return. Of course, if you've made such a serious navigational error in your kayak that you wind up in the desert, perhaps you shouldn't be paddling... Philip Torrens N49°16' W123°06' *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
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