Transpiration

C

CanDo

Joined
Mar 10, 2006
Messages
913
Hey all,

I'm not sure if I shared this already, but don't think so... Here's a video that shows transpiration being used to get water. Basically, a plastic bag is put around a branch, and the tree gives off water, which is collected in the bag. Could be handy for survival (either when water is hard to find, or there is only polluted water).

http://www.metacafe.com/watch/874761/drink_from_a_tree/

Peace,

CanDo
 
CanDo,

Nice. It should have the caveat that the tree or plant used should not be poisonous, and that the white or clear bag is used because the black trash bags tend to absorb too much heat and evaporate the usable water. Excellent!
 
Brian Jones said:
CanDo,

Nice. It should have the caveat that the tree or plant used should not be poisonous, and that the white or clear bag is used because the black trash bags tend to absorb too much heat and evaporate the usable water. Excellent!
Click to expand...

Good points, thanks :)
 
Brian - I can't think of why plant toxins would come into play, unless you mean a contact allergy that can get you while you are putting on or taking off the bag. The transpiration action is like a still, so the leaves aren't going to be relasing toxins present in their tissues.

The video seems pretty far fetched in terms of the amount of water recovered from one set of leaves over a one day period. I suppose it depends on climate conditions and the species of tree. On the RAT cutlery webpage, Mike and Jeff indicate that transpiration could be a viable method for getting drinking water but it isn't that efficient and you need to put piles of bags on a pile of plants to support your daily requirements.

Still food (water) for thought!
 
Transpiration bags do produce water but I have never had the kind of results they show in the video. IIRC I was getting about +/-50 ml of water per bag, in terms of hydration that's 20 bags per liter/quart of water. I tested this in dry season here in Brazil under the kind of conditions that were likely to require it. On the same trip I also did dew collection and was able to produce about a liter of water in an hour, sopping it up with a cloth and wringing it into a canteen cup. IMO dew collection is a far better method for collecting useful quantities of water. True, dew doesn't always form, but it is a good technique to keep in mind. One tip, get out of bed and start early! If you start well before sunrise you could easily have several liters before the dew burns off. That is enough to last a whole day. In the dry season here we get lots of dew because the nights are cold. Mac
 
I have tried transpiration bags twice. Poor results, only a couple of ounces each time in pretty ideal conditions.

KDG - Brian is right about avoiding toxic plants. I understand your thoughts as it would be like distilled water (which is may), but it is not worth the chance. Take Poison Sumac for instance, the oils are still going to come in contact with the bag and I can't see how it could reasonably avoid the water, thus making a solution of poison sumac. Just like poison ivy, you got to make sure you rinse it completely off as a little water may just spread it around.
 
My gut response to the video is that he's in a humid area in which the temps dropped a lot, and that his "transpiration" is more water vapor condensation.

I'd be curious to see a test in which he tied a bag around a PVC fake tree as well, and see how much water he got from that.

Though I say this, I did notice the leaves in the bag were pretty dry. With standard condensation, they'd be wet. Transpiration, not so.
 
Yeah, the results are somewhat exaggerated for metacafe viewers. In reality it pulled at least 8oz though, which is certainly better than nothing. It's still winter right now, but I'll test out Watchful's condensation theory when the weather is similar. I'm told this is a magnolia tree (though it's never had flowers, so I don't know for sure), which is definitely not native to New England. More objective experimentation is called for :)
 
CanDo, was this YOUR video?

I don't think New England produces enough humidity to make my suggestion useful. If this were St. Louis...!

Also, if you are interested in a control, you don't need a plugged PVC section: you can basically tie the bag around anything that won't transpire.

If you get water in it... well, then you have a rough guess as to how much was contributed via condensation.
 
kgd,

Yes, it's contact that can make it dangerous with poisonous plants, and some plants may bleed their oils onto the bag, and collect at the bottom with the water.

Best way to make this work is to have many bags. It's much better than a solar still, and it works for you while you keep looking for a better source of water -- better than nothing.

Also, to make it more productive, it's more efficeint to cut a small hole at the bottom of the bag and drink out of it, then tie it off, rather than taking the bag on and off the tree or plant each time.
 
CanDo said:
Yeah, the results are somewhat exaggerated for metacafe viewers. In reality it pulled at least 8oz though, which is certainly better than nothing. It's still winter right now, but I'll test out Watchful's condensation theory when the weather is similar. I'm told this is a magnolia tree (though it's never had flowers, so I don't know for sure), which is definitely not native to New England. More objective experimentation is called for :)
Click to expand...

CanDo, an additional word about demonstrations: I understand exaggerating the results in order for the camera to pick up the water in the bag, but I am a huge believer in accurate survival information -- there should be a disclaimer about the amount of water, and/or the video should be reshot to reflect reality. Without a disclaimer, a viewer may think they will get better results than are possible, and any information that ends up being used for real might kill someone if it's not accurate.
 
Brian Jones said:
kgd,

Yes, it's contact that can make it dangerous with poisonous plants, and some plants may bleed their oils onto the bag, and collect at the bottom with the water.

Best way to make this work is to have many bags. It's much better than a solar still, and it works for you while you keep looking for a better source of water -- better than nothing.

Also, to make it more productive, it's more efficeint to cut a small hole at the bottom of the bag and drink out of it, then tie it off, rather than taking the bag on and off the tree or plant each time.
Click to expand...

Smart idea about the drinking hole!
 
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