The solar still is the most written about yet least used survival technique there is. I would like to help change that, with some actual testing and practical knowledge, back to something you can really use for survival.
If you ask almost anyone that has read a book on survival, or taken a summer wilderness class, how they would acquire water in a desert environment, without hesitation they would say: “I would just build a solar still.” There is nothing wrong with that; it is one way to attain at least some water. The solar still is the stock answer, and not a bad one either. The desert is a harsh environment short on water and the ground is the only real place to find it hiding. Desert vegetation is extremely hard to squeeze palatable water from. Contrary to what you have heard. cactus, even the infamous Barrel cactus, do not contain enough refreshment without d’stilling their contents to sustain anyone. And if you have not had the opportunity to try sucking moisture out of a Barrel cactus, do not bother, Bleeeech. In fact, it will make you even thirstier, and some people even sick.
There is a problem, however. The next thing that same person will tell you almost in the same breath is: “But, they don’t work very well, and you wouldn’t have enough water to live on. Not to mention it wastes more sweat to build than you could replace with it.”
Those are all completely true criticisms.
Solar stills are inherently inadequate for evaporating the moisture from the ground, and any vegetation that you might add to it, into drinking water. There has only been one design in the history of its conception. Well, at least since they have been recorded in books, as far as I can tell. It’s like viewing the same photo, penned by the same hand, knocked out time and again from the mid-fifties in every book. Every one of them has it-- cut and paste, almost. As well as the same way too short paragraph description only slightly modified to avoid plagiarism.
The picture is a very plain line drawing of an inverted cone-shaped hole in the ground, out in the middle of a flat and barren land with nothing else around, and a sheet of plastic stretched over the hole to match the conical hole. There's a cup centered at the bottom, and then they always say--”a small stone or pebble” in the center to hold the point of the plastic to that cup. If you have a decent manual, it will explain that this old technique is used for a “if nothing else is possible” situation, and not advisable to try unless you're going to die anyway. Solar stills work, just not very well. That just bugs me.
So why put it in the book in the first place? Why waste that valuable space in the book? It would be just as easy to teach, “If you're going to freeze to death anyway, try and find a hibernating bear to snuggle with." It does not make much sense; if it can be better, than why not do it?
What if I told you that there is a better way. One that works. One that is worth it. One that could and will save your life and maybe loved ones with you. I know you need to know. Like me, you are a survivor. You will learn and will do what it takes to continue to live. That’s why you're reading this now. Knowledge is power, and more.....it's life.
So let's get started. First, a short history of the solar still. The first recorded sun-powered still ideas were made by the Arabs a millennium ago. They developed some of the modern things that we take for granted today, such as mathematics, and celestial navigation, etc. The first practical designs are credited to a Frenchman, Adam Lonicier in the year 1561. And then yet another Frenchmen, Agustin Mouchotin, in 1861, was the next in line to copy or alter this idea to his own ends while he was working on a way to refine the brandy business. It didn’t work out the way he expected, though. The man that first took the concept to its fullest modern day design was an American named Charles Wilson, in 1872. On a mining expedition in Chile, he developed a system of ocean-fed canals in large proportions and was able to purify enough water for a small city. That very same solar still worked without problems for more than forty years. Now, all of these designs were large, non-portable devices to gather moisture to supply their homes or cities.
In the US, we might have known and used solar stills since its founding, but it was first used as a “portable survival plan” in the First World War; at least, the original commercial printings date back to that time. Those plans became standard operating procedure, though just as a very last resort, from the Second World War on. Solar still kits with plastic sheets have been standard issue in Air force birds since 1960. And the only way they have changed is in the rotation of that kit for freshness. The conceptual design has remained exactly the same for these past 70 years.
There have been some improvements here and there to "solar stills. In fact, others came up with the concept of small portable blow up (for a boat or plane traveling over water anyway) solar stills that can be used while adrift in the water, and are now standard military on every boat/plane that would carry more than three people. These are based on the exact configuration of the in-ground models and really have but one extra benefit..... the unlimited supply of water.
The other improvements have all been made to the non-portable home units now being built with new space-age materials. They have changed the materials such as the covering glass and used reflecting mirrors, and added +/- 5 % here or there, varied the depth of the water or the insulation under it, as well as colors and gained a few more percentage points, and so on. The one thing that made a huge difference however, was if you could hold the inside of the still in a vacuum. This will improve the workings up to 100%. I know of no way to achieve that with a hole in the desert floor and pocket materials, unfortunately.
These changes also have nothing to do with a “wilderness survival solar still”. Not unless you can carry an entire hardware store in your pocket. In that case it would be easier to just carry the extra water. The wilderness solar still design has not changed at all. It’s still just a hole in the ground, with little science involved other than trying to evaporate water.
Until now.
My wilderness solar still, described here, has an increased output of over 400% . So, how does one improve on a hundred year old hole in the ground? Like most people, I have heard and read about Solar stills for my whole life. I have implanted the illustration to memory, cataloged and filed. But when was the last time you ever built one? You do go out and build
at least one of these every year, right? Testing with the various substrates, soil conditions, and atmospheric anomalies that will give better results, right?
Wait, you don’t? Me neither. I never did, until a little more than 15 years ago. Oh, I played around a bit with them when I was a kid, but never seriously. Why would I? If it’s been written in the books for 70 years of course I can trust it. Right? Well just like anything else, I want to “know” what I can and cannot count on. I need to know how much liquid can one get out of, say, a four foot diameter model in the Arizona desert in mid-summer, with the materials I carry.
This was not answered in any book. In fact not too much is ever mentioned in any survival books about solar stills except the simplistic version on how they are made, and that they do not work very well. If it was a firearm, would you trust that it fires accurately because a book publisher that printed off millions of copies said that it did, and that once purchased there would be no need to test fire it? Well, I guess a lot of sheep--I mean people have done that a few times.
Everything that one will rely on for survival should be run through its paces to find its weaknesses and its breaking points and faults. Find out if you can depend on it, or if it is worth the weight in your pack. Or, you can pack it and wait to find out later when there are no other options. I know several people right now that have all the fixins for a dandy of a solar still in their B.O.B.s. At best they have only imagined ever making one. Again, relying only on those books with the same short descriptions and same simple picture, they trust that in a dire time of need it will work just fine. It does on television! I bet that half of them will not even know how to dig the hole in hard soil without a shovel in their bag.
I fear that is the way with a lot of gear, though. Like carrying condoms in a small survival kit. Someone spread that around long ago and it stuck. I’m sure it came out of Viet Nam. Latex was just starting its heyday and they were being handed out like gum. Sorry about the pun. Today rookies are still adding them to their kits, and some do not even have a clue why.
Not that long ago, I had someone on a preppers board post the list of contents of his “kit'” and I gave a few suggestions with a list of my own. He thought it was great that I added a few plastic Ziploc bags--”I could use one to carry water in if I had to”, as well as fifty other uses for them. He said he should have something like that as well. But he had listed two condoms (no spermicide or lubes). I asked what he used those for--chance encounters? He did not have a clue. He had no idea why they were taking up space in his kit. Not to mention that they do not make very practical water carriers.
There are better ways.
I am the sort of man that has to go test things. To find those better ways. In fact, every year, for three to four days I go out somewhere with only my small survival kit, and some hopefully unused emergency-only safety gear. I see what the kit is made of--or really--how I made it. Added to that are the numerous backpacking trips, hunting/fishing excursions, and the like. All are great times to test out gear. If it can be improved, it gets revised. It will never be perfect, but there is never a perfect emergency situation either. They just happen, and the kit is there to help fill in some of the gaps. The main revisions are in the knowledge and thought base and can change with the area you're in, and adapt what you have or find without having to carry any extra gear. I even revised a common motto: Practice what you think you know, and know what you have practiced.
The solar still is no different. I want to know what to expect, even if I lived in, say, Minnesota, or somewhere else water is not such a commodity; I would still want to know if and how they work. You never know when you might end up in a completely different environment than what you’re accustomed to.
Like most others, I took the solar still for granted for too many years. Until one day someone asked me how they worked and why. I started quoting the text books. Gave the same answers in the beginning of this article. Somewhere in the middle I caught myself and started rethinking the idea of actually testing them out and seeing with my own eyes how they went so wrong, and what they can do in a real-life situation. I wanted to see if I could improve them so I would not have to give those same horrible answers.
I reside north of Phoenix, Arizona these days, the perfect Area of Operations to test such a thing. It’s great here in the off-summer times but H*ll the rest of the year. There is not much water in the cool months and none in the hot. On the whole, it’s dry. One has to plan his outings around water. Either hike to it or carry enough of it--there is never enough.
At a minimum, once a week the local news has a story of at least one adult going missing on a mountain hiking trail that is right in the city. Worse, at least two or more times a year there are persons missing in the Superstition Mountains east of the major cityscape. They are usually found in one to two days, thanks to well-trained Search and Rescue people, though it sometimes takes a lot more time. Most of these people are not from here or another desert area. They never have very much water with them, if any. They all started out as a simple three hour hike to the top of some peak that you can see from almost any place in town. A little bit of not paying attention and oops, they’re in another canyon that looks like the last seven they were in. Like most lost people they think, “If I just can get up around the next bend I will see where I messed up”. They are almost always wrong. These people should have the proper knowledge and carry the simple tools to provide for themselves just in case. In these situations I would suggest at least a full Camelbak and a charged cell phone. For those that venture out further, a lot more will be needed to survive this deadly place till you are found, or you find your own way out.
A Better Way
You will not find this in any of the survival books or in any print that I have not laid down. I came up with this on my own accord and have tried to inform people about this and other things that I have come up with to increase their chances of survival. I appreciate the opportunity Mr. Rawles has given me here to reach an audience of intelligent and like-minded preppers. I hope others will glean something from this and take it yet another step further.
You know what they say: If you can save just one life—well, it’s very true. Accidents happen all the time, and I could not even imagine something like watching my kids thirst for water that I could not provide for them.
“So, what heavy, fancy new gear do I have to add to my kit this time”, you're asking? Nothing. One more time: Not a thing! If you carry a hunk of plastic and a cup now for a solar still/E-shelter, that will continue to be the only thing you need. Think, for example, if the first car tires were square they would not work very well, and with just a small alteration in shape and no extra material we could get them spinning down the highway. Everything that I will try to detail out to you now I have taken to the field and tested personally. I started with baselines, building exact replicas of the solar stills in the survival books. I tested these in various places at various times during the year to get a good average base to draw from, and testing things my way in the same places and times of the year. These test that I have carried out were completed in the deserts around Phoenix, Arizona right around 1,600-foot elevation. I also have several other test sites in Northern California that I use at various times of the year.
Now unfortunately you are still going to have to dig a hole. It will be similar to the one that you should already be used to seeing in the books. This should be a hole at least five feet across; six feet would be even better. I have made plenty of them that were only in the four-foot diameter range and they worked well. The bigger, in this case, the better, materials permitting. The smaller ones that I have constructed had limitations of landscape rather than my just being lazy. The plastic I normally carry is about 6x8 feet and can be used for a quick shelter or what ever is needed most at the time.
The first difference you will notice is, instead of having a round hole with the deep point ending in the center, I want you to dig it in the shape of a common looking seashell. The shell that you should have in your minds eye is the iconic “Shell oil” sign design. When laying this shell shape out on the ground in the size that you would need, you will have to make sure that the top rounded side of the shell points away from the sun's tracking through the sky. In North America that would be to the north. To explain from a different angle, you want the sun to track east to west across the bottom third of the shell from right to left. The importance of this will be evident before we are through.
The top rounded section, or north side, would function much the same as the conventional still with sloping sides with approximately 25-45 degree angles, to as deep as you need the hole. The slopes would end not in the center, but on the bottom side of the shell shape about three quarters of the way down from the top, on the south side. The sides might have to be a bit steeper to end at the same point; that’s just fine. The bottom of the hole does not have to be a point, either. If the ground turns excessively hard, half flat is okay. The only need for depth is trying to get down deep enough to find damp soil. If you find damp sand a foot deep, you can stop there, but make sure that you will have enough vertical room to make the plastic work with your catch container.
This is tough without a simple picture. I have posted links to Photobucket. They are not masterpieces, just a simple computer “Draw” diagram.
Illustrations:
The bottom of the shell area with the squared off “tail” is not sloped very much unless you have to, and you might have to because of sandy or very loose soil. If this is the case, slope only as needed. If you have a few rocks laying around they can be used to bolster the sides to keep the shape of the hole. In fact, keep rocks in mind while gathering supplies
because later in this article I will explain how adding rocks to the inside of your still will be beneficial.
One other thing to remember is that the solar still might have to be used for a few days and in loose soil the common man-made erosion will quickly fill up or change the shape of the solar still. Adding rocks may also stop this from happening. To minimize all this digging, use the spoils from the hole to raise the sides, increasing the depth with half the work.
The bottom of the hole is not one level. At the bottom, the “tail” end of the shell is a raised shelf. This shelf will hold the catch pot. I know this sounds a little complex but with the cross-section illustration it should be very simple. I will post a cross-section that is very easy to understand, coming up soon.
There are only three other things that you have to do before you can cover your still. The first is very optional. If your soil already has some moisture to it and is somewhat dark in color you may skip this step. If not I would recommend that you look around for any vegetation that you can collect and add to the hole. If you have any of that cactus that you thought that you could eat and had to spit out, chop it up and add it to the hole. Anything with leaves that’s not poisonous or will cause you great harm in harvesting will be fine. Grass is very good and holds a lot of moisture. It can all be broken up into parts just long enough to line the bottom and sides of the hole. Make sure that once the plastic is pulled over and angled that the vegetation will not make contact with the plastic. If it does it may siphon off those valuable water droplets before they get a chance to run to the cup.
The added vegetation makes two things happen. First, it will add more moisture to the distillation process, and second, it will help the bottom of the hole to be a darker color, if you have a light soil. Dark colors absorb more heat. This is also the time to add any other items of moisture. If you are by the sea, add sea water. If you are close to a cow-trampled mud wallow, add some cow patty mud to the still. If you have to urinate for god sake do not waste it in the bushes, pee in the still. Do not worry about it being gross or about what is in the water. The lower heat that is generated by the sun instead of fire will only vaporize the water molecules and leave the other things in the bottom of the still. You can even use radiator fluid as a source of moisture to add to your still. Do not under any circumstances try and drink radiator fluid without processing them through a distiller. (Ed. Note: Bad idea! Many auto coolants contain Methanol, which evaporates at a lower temperature than water. Methanol is poisonous, and will kill you by destroying your liver.)
The second thing that you should add is small rocks. Not too small, about fist or palm size or bigger, and flat if possible, any shape is okay if not. The ideal rocks would be very dark river rocks about 4-6 inches around and 1-3 inches thick. But when picking up rocks in the desert make sure you do it carefully. Some critters use them for houses. A bite or sting is the last thing you need in a survival situation. The rocks should be placed along the inner sides and bottom of the still. They serve two purposes. The first is that they collect heat, being a darker and a denser material. And second, they hold that heat past the time when the sun drops below a level that hits your solar still. This will change the name of your solar still to the “stored heat radiation still”.
The still works on simple properties of moisture evaporation. This is accomplished with heat. The longer you apply heat the more water you can make. In fact, the time of day your still makes the most water, believe it or not, is after the sun goes down. If you have done everything correctly, the heat should continue radiating out of the rocks while the air above the still should be getting cooler. This will condense more water faster than in full sun, at least for a while. It will also extend the time past the “sun hours” that you are still making water. We are trying to create a wide difference in temperature, inside the still and out. As the temperature on different sides react to each other, they are still making you water.
The third thing to add before sealing your solar still is the container to hold the water that we hope will fill it several times. Just make sure that it is stable on the shelf that was constructed just for this vessel. If it falls over or you knock it over trying to remove it, you could turn a bad situation worse, if not fatal. This container can be almost anything that holds water--a pan, jug, plastic car part with dirt under it to make it stable, plastic bag with dirt to hold it in a cup shape, or a soda can or bottle with its top cut off--basically anything you have that’s clean and will hold water. I prefer to use larger pan-type catch basins. This makes it easier to position the point that water will drip from.
Not everyone will be carrying a length of tubing long enough to reach comfortably from the top to the bottom of the still and also be secured. Not having to open the still after its closed, however, will help with maintaining continuous heat trapped in the solar still. Any loss of heat will take a period of time to regenerate. Really the only time you would carry a tube long enough is if you were carrying it just for solar still construction. There are other reasons to carry tubing in the desert, though not that long. One of them is to gain access to trapped water in cracks and such that you would not be able to get to any other way. So adding a few extra feet might make things easier if you plan on using a solar still. What is the right length to carry? Go try it out yourself. This will depend on many variables--the depth of the hole is the main length but other factors will come to bear in the installation. If your kit now contains six feet, that will be more than sufficient.
So, we have our hole in the right shape--I will explain why in a bit--and we have it lined with rocks and/or vegetation. We have also tried to add as much moisture that we could find, as well as making sure that the catch container and the tubing, if used, will not be accidentally tipped or moved. It’s time to cover the solar still.
The plastic used can be any that you have. Clear or black, blue if that’s what you’ve got. I prefer the clear to opaque. Why? I want the heat, especially the infra red light, to pass easily through the plastic and do its heating “inside” of the hole. And I want the plastic as cool as possible. If it was black or a darker color, the plastic itself would be heated and it would change the temperature ratios and alter my expectations. Now if all you have at the time is black plastic, then use it. It works too. Some people even say that it’s the black that works better. I will not. You can make your own choice. For these results pack the clearer shades. Next the plastic is carefully stretched out over the hole, then using the spoil piles removed from the digging placed over the plastic all the way around the edges. On the south or the “tail” side of the still, I run the plastic up halfway into the spoils pile. This will give me a steeper angle on that side. When this is covered with the condenser material it will also help increase the reconverting of vapors in concert with the condenser.
There are two things that you have to be careful of here. The first is, that you leave enough slack in the plastic to have it dip in the middle, very similar to the original concept. You should first drape the plastic over the entire still and secure it in several places first, so you can make adjustments as needed before you bury the whole edge. The second is that once you start to seal the edges you should make sure to keep them as sealed as possible. You do not have to bury them with tons of dirt, but they should be as held down securely
and without many bigger rocks under or above it. You are trying to make the inside as airtight as you can under such primitive circumstances. I have seen many solar stills, constructed by untrained persons that have learned from these incomplete books, that have only one rock on each corner to hold the plastic down. This is not enough. Outside air entering the inside will not only cool but dry out the air inside of the still.
Now we are getting to the important parts. The rest was important but similar to a conventional still. From here out it changes dramatically.
Again, a little history before we go further. A solar still is a simple still. One has to look and think of it just like any other type of still, however. If you have any schooling and remember chemistry class you will remember how to distill water on a stove or lab tabletop. Very simply, heating water over a flame turns it into vapor and rises. At the top of a tapered flask it turns drastically, which helps it make contact with the walls of the tubing. Once out of the flask it is directed into a condenser. The condenser in this case would be a larger tube around the smaller tube that the steam is flowing through, with cool water flowing in between the two. The instant the steam contacts the sides of the cooled tubing it turns again into liquid, and flows out of the end of the condenser into a catch container. Even if you are distilling alcohol, you would do the same thing. Heat a liquid, turn it to steam and let it rise. Once it is removed from the heating vessel it changes direction and is cooled by a condenser of one design or another, usually cooler water Water is very good at pulling the heat out of things, especially clumsy humans. The key points are to heat, turn the water to vapor which rises to contact the plastic sheet, and most importantly, condensing back to liquid and falling into your catch basin.
In our solar still we use the hole and the plastic to trap the sun’s rays to create heat. With this heat we will turn the moisture in the still to vapor. We will allow it to rise and contact the condenser. The only thing that there is for a condenser is the hot sheet of plastic that is stretched over the hole. It does not seem to efficient. And you know what? It’s not. Not yet.
As we know, the basic solar still does work, but poorly. The thing we need is the same thing that we would have if you were making whiskey. A large difference in temperature between the cooker and the cooler. The plastic that is trapping the sun's heat is being heated itself. This does not make things better.
Most of the reasons this solar still is different from all the rest is that I add a real condenser. This makes the water condense and collect into the cup instead of recirculating around and around, cooling the inside of the still, or worse, sticking to anything that’s in the still, like the sticks or rocks that were added or even the parched upper walls of the still, which are hungry for moisture.
Rule One: The quicker you can gather the heat, make vapor, and re-condense the vapor, the more water you get back. It all comes down to that. This speed is contingent on the condenser design and temperature.
There are a number of ways you can accomplish this and it all comes down to what you have on hand. Use what you have and keep the above principles in mind. You can look at this next diagram to understand what I will try to explain to you next. Listed as “The cross section”.
To make a condenser that will cool the moisture in your solar still I recommend a two- stage process. The first is to change that simple pebble we are told to toss in the center of
our plastic to a much more capable form. Again, using what you have. If dirt is what you have then so be it, use dirt. Not a simple handful, but a pan full. The pebble will still be needed though. It will be used to hold the point where the water will be dripping from, underneath. Make sure that it is directly over your off center catch container. After that, you will continue to add soil over the pebble until a large enough patch covers an area about the size of a plate or larger. This only has to be as thick as needed to build up to that size an area, but a little more is okay and will keep the condenser cool longer. Just make sure that the plastic sheeting you're using will take the weight and not tear or stretch too far out of proportion. Remember, later in the day the now heated plastic might have changed its properties, so check on it now and then for stretching.
Keeping this upper soil cool will make a huge difference in your solar still. If you happen to have moist soil, you are golden. Keep some out from the digging of your still if you can; if not, try to find a way to moisten the soil. This time get a friend to pee on it if you have to.
Other methods that I have tested used things that I had in my pack. A small aluminum backpack frying pan with no sharp edges to puncture it was placed on the plastic. I was able to place it in just such a way as to have almost the whole bottom of the pan in contact with the plastic and still have it point to the catch container. The aluminum worked fairly well, actually, when I filled it with soil for weight and cooling. Aluminum does not hold a lot of heat but transfers it quickly, and so it makes a good material to use.
I do not recommend rocks or steel. These materials trap and hold ambient heat and would work in reverse of the way you needed. You are trying to create a place under the plastic that is cooler than the rest of the plastic, in an area about a foot plus in diameter, and evenly built up the south side to where the plastic is held down. Referring to the pictures I have provided should help to clarify any of my miscommunication, I hope.
The next part is just as important as the last one and rounds out your solar still to a lean mean water making machine. It is also one of the reasons that you had to dig the hole in the shell shape and orient it to the sun the way I have explained. It's half of the real key to the entire still: Shade.
Wait! That’s supposed to be a bad word in solar still construction, right? All the books say to stay away from all shade. No image will have a tree, let alone a small bush, in them that one might take to mean shade. So why shade?
Shading one side of the solar still will do more for making water than everything else you have done so far. In essence, you will be making your condenser cooler and making a greater difference in the temperature between the two sides. By shading the southern 1/3 of the plastic (remember the shell shape), you are creating a much cooler area that the water vapor will adhere to and which will quickly run down to the point and pour off in streams into the catch container. After you have constructed your still, make sure after the first hour that you monitor the catch, because if the vessel is small, or you are making a lot of water, it will overflow and waste your valuable moisture.
The first part of making this shade is with the spoils pile that you should have from digging the hole. You had to use some to hold down the plastic but there should be a lot left over. When in the planning stages and you are lining the hole up with the sun's tracking line, make a note to put the spoils on the southern rim of the hole. It will save you from
having to move it twice. This pile might just be enough in the wintertime. The sun tracks low in the southern sky, creating long shadows. In the summer it will just be a good thick base to help insulate that side of the hole. You will have to add to the top and maybe even the sides of it, as needed; you will have to adjust it through out the day from time to time as the sun tracks through the sky. You want the shade line to fall right across the bottom 1/3 of the shell shape at all times or as much as possible. It should fall right at the end of your shelf inside the still and the tip of the soil you have added as the condenser to the top.
What should I use for the shade? Look around. It could be anything--leafy branches of a tree, clothing items that you can spare (not ones needed for body protection--you will lose more water than you can replace when direct sun contacts more than 20% of your body), an extra tarp not needed to keep you out of the sun, maybe even something like a fire reflector design (built with small logs). Even plane or car parts. Again, take into consideration that it might have to be adjusted throughout the day to optimize the placement of shade.
While I’m at it I want to go over a few other things. Any solar still will have to be moved from time to time. There is only so much moisture in the small area of the ground under your still location and in the vegetable matter you might have placed inside. When the amounts drop off a lot, start planning the next one.
Also, you do not have to only make one, for many reasons. You might have a group of survivors that would require a lot more water, or just plain redundancy. Your solar still is a delicate structure and can be destroyed by an unforeseeable accident that could take away a needed chance at surviving.
Also, the hole does not have to be a shell shape; it can be anything that you want it to be. It is just an easy way I came up with to teach the three-dimensional aspects needed for construction with an easy-to-remember shape that just works, and includes the shelf and offset plastic not known in any other still.
Oh, and very importantly, try to keep the “pebble replacement” condenser damp, and shaded as much as possible. The evaporation of the moisture from this area will super-cool the plastic underneath, and condense vapor more quickly. This means a lot more water for you. But that evaporation will dry out this soil and allow it to warm up, decreasing production.
That’s it.
So, you want to know what all this amounts to? I know what they've done for me and for others that I have so instructed. I can tell you those facts and what to expect.
In comparison with a classically-built solar still I have, at a minimum, quadrupled the output. Let me say that again: Four times the output in the worst case environments every time. I have been able to pull water out of ground that was so bone dry a conventional solar still did nothing--not a drop. You can do better in areas that have more moisture in the soil, obviously. But then the Extreme Still will work far better, too—as much as 8-10 times better.
This may still not sound like a lot to you. Think of it this way. The reports vary, but they say you need at least 1.5 to 2 quarts of water per person, per day, to survive while resting in high temperatures. It's really more like a gallon a day, in the real world. Good luck getting that amount from a classic solar still. You might, if you're incredibly lucky, be able to get half a quart if you left it all day without a drink. Again, if you were lucky. With the Extreme Still in the same conditions, two people can drink two to four quarts per sunlit day from one still, if not more. And it will keep working long after the sun goes down, for even more water.
All these figures are relative due to different conditions but the 4:1 ratio will always stand as a minimum baseline between the two stills. It’s only a baseline as well; in some testing areas I had more than six times the results or higher as an average baseline.
The last time I was able to write something up on my new still design it had more pictures than words, I think. Maybe some here read it a few years ago. It started in an area that was powder dry. Clouds of dust arose as I dug a small four-foot wide hole with an E-tool. I think the entire thing was less than two feet deep, as well. I only had opaque plastic, and I was trying the test with almost no vegetation added for demonstration purposes, just a few Mesquite sprigs that were close. I did have lots of very dark rocks of the right size, although square and pointy. The outside temperature was more than 113 degrees, and my “shade” for the D’still was a very weird pair of plaid pants that I found twenty feet from where I dug the hole. I used two poles and some brush stuck in the spoil pile to hold the pants out and across the still for shade.
All this was completed after I had already constructed a classic still, with prime materials and a lot more care (It was a little earlier and was not so hot yet). The classic one that was set up forty feet away--text book, as they say--and was five and one half feet across. It had the benefit of “working” the entire time as I constructed the other D’still, as well as the time I let both run together.
Once constructed,, you will see within seconds after sealing the Extreme still, water droplets forming in the shaded area, clinging to the underside of the plastic. A perfectly demarcated line of refreshing water droplets filling in the shady side. Almost clear on the sunny, or hot, side.
Within fifteen minutes the temperature inside the Extreme still was up over 170 degrees. Within three hours, I was very hot and had my work calling –I had to wrap it up. When I pulled the two covers to look at my effort for such a blistering day: I received nothing from the classic still. Zero. I pulled two and a half cups out of the dust with the D’still, in three hours!
Which one do you think I will use when my life or those that I care about depend on it?
on the downspout and install a stainless steel mosquito screen on the bottom where it connects to a 
to keep the little suckers out of the tank. They will find their way into your tank otherwise. In some locations, these are required by code. 
