Came across this. Not worth the effort in the arid zone it seems.
http://www.thetipzone.com/vault/articles/outdoors_cluster/desert_mythfacts.html
http://www.thetipzone.com/vault/articles/outdoors_cluster/desert_mythfacts.html
Solar still not for desert
- Thread starter BOD
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Yeah I heard about that too. I think RM mentioned it on the first program of the new series. You would loose more water in sweat and on your breath than what you will gain from it.
Strange thing is quite a lot of survival books/resources seems to keep mentioning it as a efficient source of water.
Strange thing is quite a lot of survival books/resources seems to keep mentioning it as a efficient source of water.
depends on how you build them. if you use it as a way of extracting water from plant matter then it can be worthwhile in the same way a transpiration bag works. if you can line a hollow in the ground with something black then fill with foliage and a clear layer on top then you have a chance of some water but like the inflatable solar stills used in sea survival you rarely get a lot out of it.
militarily there are more myths about using tarps and ponchos to make stills as they rarely work, you need a clear top cover.
if you want to practise then get a cheap dustsheet for a quid from asda and make one in the back garden using grass cuttings for the moisture source. you dont even need to dig a hole. paddling pools work well
dont expect more than half a cup though unless you're lucky. if you widdle on the grass it warms up better and adds to the potential souce of moisture.
militarily there are more myths about using tarps and ponchos to make stills as they rarely work, you need a clear top cover.
if you want to practise then get a cheap dustsheet for a quid from asda and make one in the back garden using grass cuttings for the moisture source. you dont even need to dig a hole. paddling pools work well
dont expect more than half a cup though unless you're lucky. if you widdle on the grass it warms up better and adds to the potential souce of moisture.
Not worth the effort full-stop I think is the general opinion.
I've always liked the idea of these solar stills. It gives the impression you just make it then sit there and let the sun do it's stuff and you get a drink of water for very little effort. I suppose that's why the books include it a lot.
Having said that, it could be useful for getting a drink from salt water when no other water is around, as the salt doesn't evaporate with the water, leaving it fresh.
Won't keep you alive though.
try it - bear in mind its a survival situation method so the priorities differ from a bushcraft one. most bushcraft techniques have a place in survival but the same does not allways apply in reverse.
in a survival situation then you will try anything so the more things you have knowledge of then the better your chances of getting out. big debate but rm wrote a survival book before a bushcraft one.
a solar still is a two way water catcher though so could be used to catch dew or small rain showers. even in scotland they built salt pans to evaporate sea water to get the salt so a combination solar still/salt distiller could be very usefull if you were there for some time.
I reckon you could make a transpiration bag similar to the two bottle technique used to distill urine - another survival technique I wouldn't recomend as the water tastes pretty rank. its also possible to rectally infuse urine to get a bit more moisture out of it and into your system.
in a survival situation then you will try anything so the more things you have knowledge of then the better your chances of getting out. big debate but rm wrote a survival book before a bushcraft one.
a solar still is a two way water catcher though so could be used to catch dew or small rain showers. even in scotland they built salt pans to evaporate sea water to get the salt so a combination solar still/salt distiller could be very usefull if you were there for some time.
I reckon you could make a transpiration bag similar to the two bottle technique used to distill urine - another survival technique I wouldn't recomend as the water tastes pretty rank. its also possible to rectally infuse urine to get a bit more moisture out of it and into your system.
...distill urine...the water tastes pretty rank...its also possible to rectally infuse urine to get a bit more moisture out of it and into your system.
Dave, it's no accident that the word 'crazy' appears in front of your name is it?
Dave, it's no accident that the word 'crazy' appears in front of your name is it?
probably not
I'd best not say how I earned it though as you might get the wrong impression or is it too late for that
most true survival techniques are hard and unpleasant as they are designed to keep you alive which is also why mr grylls gets such bad press on top of the exagerations. people tune in to watch him eat the bugs he is probably contractually obligated to do but it does prove that they can be eaten, like the tale about opening up the hump on your living camel and nibbling on the water rich fat under there (like the camel wouldn't object). or the squeezing out of elephant dung for the moisture.
a bit like every rm episode seems obligated to show him making fire and cooking something yummy - or is that just me?
I can admit to bug eating as well allthough only one spider that I know off and that was fried - tasted like peanut butter too but I dont want another one.
Sure you can get a cup. I think Dave Alloway is saying save the effort as the water lost in perspiration and the calories burnt off are more than what can be gained.
Did two outback survival courses and the still did not feature. If you are with a car, spade, static camp with basins containers etc then it may be worth a go but with just dry ground and maybe a cactus or two forget it
Did two outback survival courses and the still did not feature. If you are with a car, spade, static camp with basins containers etc then it may be worth a go but with just dry ground and maybe a cactus or two forget it
I have made them here in Brazil and they do produce some water but not nearly enough to hydrate. I would only make one if I had dug a hole in a place that was likely to produce groundwater and only came up with moist soil.
I did an experiment once in which I spent 48 hours on a dry ridge, no flowing/standing sources of water and had to use field expediant methods to produce drinking water. This was in extreme heat. I brought water in, eight liters IIRC, to measure my actual water intake. I then tried every method I could to make drinking water and measured the amount I produced.
I had a supply of clear plastic bags, all the same size. I opened one up to make a solar still, used several others to bag branches, filled one with green leaves and left it sealed in the sun. Each of these produced about 50 ml of water. I wanted to see which method would make the most from the same size bag. The bagged branches won, because they don't require sweat to do, but they produced a dismally small amount of water.
By FAR the most effective method I used on that trip was dew collection, which netted me about 1 liter of water for an hours worth of work (sopping it up with a cloth and wringing it into my canteen cup). If I had started earlier it would have made me 3 liters easily.
My total water use in that 48 hours was 6 liters and that wasn't trying to ration, I just drank freely whenever I felt the need and used none of it for washing. Mac
I did an experiment once in which I spent 48 hours on a dry ridge, no flowing/standing sources of water and had to use field expediant methods to produce drinking water. This was in extreme heat. I brought water in, eight liters IIRC, to measure my actual water intake. I then tried every method I could to make drinking water and measured the amount I produced.
I had a supply of clear plastic bags, all the same size. I opened one up to make a solar still, used several others to bag branches, filled one with green leaves and left it sealed in the sun. Each of these produced about 50 ml of water. I wanted to see which method would make the most from the same size bag. The bagged branches won, because they don't require sweat to do, but they produced a dismally small amount of water.
By FAR the most effective method I used on that trip was dew collection, which netted me about 1 liter of water for an hours worth of work (sopping it up with a cloth and wringing it into my canteen cup). If I had started earlier it would have made me 3 liters easily.
My total water use in that 48 hours was 6 liters and that wasn't trying to ration, I just drank freely whenever I felt the need and used none of it for washing. Mac
a lot of aircraft survival kits now include compressed sponges for dew collection which is good.
it would be interesting to see how much sweat is lost compared to just lying around and how much you use digging in the dark. I think if you were building a sunshade and insulating it with sand then a scooped hollow would be the by product which could be used. a lot of survival activities are pretty hopeless in their return but they do give you focus and the chance to acheive something to raise morale. I suppose then its like firemaking, a lot of experts say if you arent sure of definate success then dont bother as the resulting morale drop can finish you off.
as to quantities then on of the older rm episodes featured the story of a lost soldier/airman from ww2 who cut open jerry cans and licked the condensation from the insides every morning. so desperate measures again
out of curiosity do the bag yields get any better the longer you leave them?
it would be interesting to see how much sweat is lost compared to just lying around and how much you use digging in the dark. I think if you were building a sunshade and insulating it with sand then a scooped hollow would be the by product which could be used. a lot of survival activities are pretty hopeless in their return but they do give you focus and the chance to acheive something to raise morale. I suppose then its like firemaking, a lot of experts say if you arent sure of definate success then dont bother as the resulting morale drop can finish you off.
as to quantities then on of the older rm episodes featured the story of a lost soldier/airman from ww2 who cut open jerry cans and licked the condensation from the insides every morning. so desperate measures again
out of curiosity do the bag yields get any better the longer you leave them?
Dave,
I left a bag on for approx. 18 hours and 'netted' about 400 ml of water. A big clear garbage sized plastic bag.
After that, or maybe even before that, you are just,killing the leaves and production will slow.
That site was the edge of a tropical rainforest, where I would think if you are able to move safely, it would be best to look for running water.
Pict,
I was once stuck on a ridge with little water. I used my scrim (net scarf) to collect water from forks of trees etc.. Must have got about 300ml. Tasted awful. Not sure if that was the water or the scarf!
Dew is good. Australian aboriginals would tie absorbent fiber around their legs and walk through the bush wringing it out when full.
In the 1940s, the crew of a downed bomber survived in the Skeleton coast of Namibia by licking the dew off the plane's wings every morning
I left a bag on for approx. 18 hours and 'netted' about 400 ml of water. A big clear garbage sized plastic bag.
After that, or maybe even before that, you are just,killing the leaves and production will slow.
That site was the edge of a tropical rainforest, where I would think if you are able to move safely, it would be best to look for running water.
Pict,
I was once stuck on a ridge with little water. I used my scrim (net scarf) to collect water from forks of trees etc.. Must have got about 300ml. Tasted awful. Not sure if that was the water or the scarf!
Dew is good. Australian aboriginals would tie absorbent fiber around their legs and walk through the bush wringing it out when full.
In the 1940s, the crew of a downed bomber survived in the Skeleton coast of Namibia by licking the dew off the plane's wings every morning
I did my experiment as realistic as I could. I did it during our dry season, the only time you would be forced to use such methods.
I'm sure there are a lot of variables with bagging branches. At the time I did it it was near desert conditions and I'm sure there wasn't much sap running. One side note. I went back up to that ridge a few weeks later and all of the branches that I had bagged had died, something to remember.
I'd like to find some of those compressed sponges for my kit. They don't seem to be available here in Brazil. My point with the dew collection is this... If you have an entire landscape turning itself into a collector each night then bob´s your uncle. Sometimes in dry season the dew starts to form shortly after sundown and gets to the soaking wet stage by early morning. By 9 AM the land is bone dry again. Dew collection in the early morning doesn't require any sweat and if you start early enough you can easily collect enough to actually HYDRATE during the day.
If there is enough dew to lick off a downed aircraft with your tongue, how much would you net each night if you swiped the entire plane down with a shirt and wrung it into a cup? Its just a matter of using a larger tongue!
The water quality is low as the dew collection method will also pick up all of the dust and bird droppings covering the leaves/grass. You have to filter/treat the water. At least here in central Brazil you can multi-task and head off into the tall grass to catch grasshoppers (abundant) while soaking up dew. In the morning before sunrise they are cold and slow. The lizards are out trying to catch the first rays of sun at that time too. Mac
I'm sure there are a lot of variables with bagging branches. At the time I did it it was near desert conditions and I'm sure there wasn't much sap running. One side note. I went back up to that ridge a few weeks later and all of the branches that I had bagged had died, something to remember.
I'd like to find some of those compressed sponges for my kit. They don't seem to be available here in Brazil. My point with the dew collection is this... If you have an entire landscape turning itself into a collector each night then bob´s your uncle. Sometimes in dry season the dew starts to form shortly after sundown and gets to the soaking wet stage by early morning. By 9 AM the land is bone dry again. Dew collection in the early morning doesn't require any sweat and if you start early enough you can easily collect enough to actually HYDRATE during the day.
If there is enough dew to lick off a downed aircraft with your tongue, how much would you net each night if you swiped the entire plane down with a shirt and wrung it into a cup? Its just a matter of using a larger tongue!
The water quality is low as the dew collection method will also pick up all of the dust and bird droppings covering the leaves/grass. You have to filter/treat the water. At least here in central Brazil you can multi-task and head off into the tall grass to catch grasshoppers (abundant) while soaking up dew. In the morning before sunrise they are cold and slow. The lizards are out trying to catch the first rays of sun at that time too. Mac
Ive tried this twice in the dessert now, once the Sahara and once in Iraq(in a quite area!).
Each time it has been very disapointing, as mentioned NOT worth the effort even though every books does still (pun ) have it in.
What I found does work well for a couple or three goes, is if you have two plastic bottles or even bags, is urinate in one and connect to other container laid on sand slightly higher!!Then cover over last so it condences on inside. Over a 24hr period you get about a cup full back for very little loss of moisture.
Each time it has been very disapointing, as mentioned NOT worth the effort even though every books does still (pun
) have it in.What I found does work well for a couple or three goes, is if you have two plastic bottles or even bags, is urinate in one and connect to other container laid on sand slightly higher!!Then cover over last so it condences on inside. Over a 24hr period you get about a cup full back for very little loss of moisture.
I've made them at about 45 degrees north latitude (united states) in mid-summer. Indeed, it is hard work that in hot weather could be dehydrating.
The key, as in everything, is proper site selection. You need damp soil where it is likely to stay damp even after repeated use. it is likely desert sands, unless in a stream bed where the sand is moist, will not produce simply because there is not enough moisture within the sands.
The best I have done is perhaps a pint per day but if you are in an area for extended period of time you can see there could be some advantage.
But, for the inexperienced, chances are making a solar still is not going to save you.
The key, as in everything, is proper site selection. You need damp soil where it is likely to stay damp even after repeated use. it is likely desert sands, unless in a stream bed where the sand is moist, will not produce simply because there is not enough moisture within the sands.
The best I have done is perhaps a pint per day but if you are in an area for extended period of time you can see there could be some advantage.
But, for the inexperienced, chances are making a solar still is not going to save you.
Ive tried this twice in the dessert now, once the Sahara and once in Iraq(in a quite area!).
Each time it has been very disapointing, as mentioned NOT worth the effort even though every books does still (pun
What I found does work well for a couple or three goes, is if you have two plastic bottles or even bags, is urinate in one and connect to other container laid on sand slightly higher!!Then cover over last so it condences on inside. Over a 24hr period you get about a cup full back for very little loss of moisture.
now when i hinted at this they kept asking whether thats where the crazy came from - glad I'm not the only one - it works but you do suffer in the drinking process. and you still need bottles.
Ah, ha! See what you mean Dave! There I go just skimming through the thread again and not reading all bits....it'll get me into trouble one of these days!
Water/
didn't taste too bad to me and the lads.......
Water/
didn't taste too bad to me and the lads.......
well I'm off to egyptcestershire in a few weeks so I'm tempted to make a still on the beach and see if its any good for seawater distillation
does anyone know if I can I take my bucket and spade on the plane anymore?
does anyone know if I can I take my bucket and spade on the plane anymore?
Crazydave,
I'm about 8 hours inland here but I have always wanted to try a solar still on a beach. One design I'd like to work out the details for is an above ground solar still, set up like a tent rather than a hole. If you could eliminate the digging you eliminate the sweat too and whatever you produce would be in the plus category.
The way I have it pictured is a small, clear plastic tent set to catch the condensation as it runs down the inside and built on a slight slope facing the sun so the water collects at one point. If the seawater was placed in the center in a "kiddie pool" made from a black bin liner all the better. Just an idea. Mac
I'm about 8 hours inland here but I have always wanted to try a solar still on a beach. One design I'd like to work out the details for is an above ground solar still, set up like a tent rather than a hole. If you could eliminate the digging you eliminate the sweat too and whatever you produce would be in the plus category.
The way I have it pictured is a small, clear plastic tent set to catch the condensation as it runs down the inside and built on a slight slope facing the sun so the water collects at one point. If the seawater was placed in the center in a "kiddie pool" made from a black bin liner all the better. Just an idea. Mac
Yes, that's the idea. The inflatables work on the same principle. IIRC there is a line drawing of one similar in the SAS manual. I'd like to work out a roll-up, DIY version made from black and transparent plastic that could be filled with vegitation or salt/contaminated water/urine/etc.
Solar distilation does produce fresh water, its just the sweat penalty you pay digging the hole that makes it a bad option as the technique is typically taught. Inflatables like the one in the photo have kept people alive in the past. Who was the guy who spent like 2+ months at sea? He drifted across the mid Atlantic and drank from these IIRC. Mac
Solar distilation does produce fresh water, its just the sweat penalty you pay digging the hole that makes it a bad option as the technique is typically taught. Inflatables like the one in the photo have kept people alive in the past. Who was the guy who spent like 2+ months at sea? He drifted across the mid Atlantic and drank from these IIRC. Mac
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