How to Set up a Transpiration Bag to Collect Water?


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What is arguably the most important survival skill?

How to find water. We all know how important water is to our health and well being and if stuck in a situation where it threatens your survival it’s important to know some cool ways to find it.

This article will look at one of the ways to find water and answer the question:

How to set up a transpiration bag to collect water?

  • Find a tree or bush that has a large number of healthy leaves
  • You will need:
    • Large piece of clear plastic or plastic bag
    • Cordage
    • A clean, small stone
    • Non poisonous bush or tree
  • For best results look for one in direct sunlight
  • Check leaves for bugs, mould or mildew
  • Place your small stone in bottom of bag
  • Place your bag over a large leafy branch and tie off over the stem
  • Tie it really tightly so you don’t lose any water vapour
  • Wait 4-5 hours for water to collect in the bag
  • Before drinking, pour water through some fabric to filter out any debris
  • Rinse and repeat

Above are the basic instructions. You can of course develop your own preferences. Some people like to add a straw to their bag so they can drink directly from it.

This is a great way to drink directly from the bag and make sure you don’t lose any of that valuable water.


To use the straw method, find a hollow plant stalk. Cat tails or river reeds work well. Clear it out and make sure it’s hollow. Make a hole in side of bag to insert straw and put it right to the bottom of the bag next to the stone as that’s where your water will collect.

Make sure to tie off the new opening you made with the straw so that no water can evaporate.

Let’s look at it in more detail….

What exactly is transpiration?

Where there are plants, there is water!

Plants absorb water from the ground by the process of osmosis. A tiny percentage of this water is used by the plant and the rest is evaporated through the leaves. Evaporation of water in this way from the plant is called transpiration.

Here’s a short video that explains the process of transpiration in more detail if you are interested:

Why is using this method of collecting water a good idea?

Compared to other methods of collecting water collecting water using a transpiration bag is NOT labour intensive saving your valuable energy for other tasks.

The water you collect from the plants is clean! That’s right, as long as you are careful not to use a poisonous plant you can drink the water that you collect without having to boil it – though of course you may want to do this.

You will not harm the plant using this method and you can repeat on different branches over and over again.

Although not huge amounts of water is collected using this method, you can use several bags to multiply your results.

How does sunlight affect transpiration?

By placing your transpiration bag in direct sunlight you will dramatically increase the amount of water that you can collect.

Air temperature has a big effect on how much water evaporates from the plant. When the bag is in direct sunlight it heats up.

The amount of water in the plant doesn’t change, it is the ability of the air to hold more water that improves. This is because when the air is warmer, it can hold more water.

It is essentially less humid or drier air. Cooler air can hold less water as it is, relative to the warmer air, more humid.  The result is warmer air increases the rate of transpiration from the plant and cooler air will decrease it.

Why is it better to use a clear plastic for your transpiration bag?

For transpiration to work the process of photosynthesis needs to be happening. This only happens during the daytime with plants as they need light.

By using a clear plastic, you make sure that the leaves are still getting the light they need for the process of photosynthesis and transpiration of water occurs at a much better rate than if you use a coloured plastic bag.

Is the transpiration bag method of collecting water a better method than a solar still?

If there are no viable bushes or trees….no.

Otherwise it seems far easier and less labour intensive than the digging required for a solar still.

Without any plant life then a solar still is well worth knowing how to build and I’ll definitely be researching the specifics of that for an article soon.

How to tell which bushes and trees NOT to use for transpiration method – which ones are poisonous?

The best way to know if a bush or tree is poisonous is to educate yourself on your local varieties of poisonous plants.

As forest and fauna are so specific to each region and there are SO many different plants, it’s best to focus on the indigenous plants that affect your local wild area.

For example we don’t have poison ivy or poison oak here in the UK, but for our friends across the pond, it is prevalent.

There is a traditional rule ‘’leaves in three, let it be’’ which applies to poison ivy and poison oak. This is handy but of course does not apply to all poisonous plants.

Here’s an fantastic guide by Sandra J. Baker that goes into lot of detail in how to identify poison oak and poison ivy:

Below is a table to help getting you started in identifying trees and plants not to use for transpiration.

Poisonous Trees, Shrubs, VinesPhotoToxic PartSymptoms
Azalea (Rhododendron)All partsNausea, vomiting, weakness, dizziness, difficulty breathing, loss of balance.
Bittersweet (false)All partsAbdominal pain, rash, vomitting
Black Locust TreeBark, sprouts, foliageChildren have suffered nausea, weakness and depression after chewing the bark and seeds.
 Buck Thorn  Leaves, Fruit Intestinal
 Buckeye (Horse-chestnut)  Leaves, branches, flowers, fruit, young sprouts, seeds Nervous system, inflammation of mucus membranes
 Cherries; Wild and cultivated  Twigs, foliage Fatal. Contains a compound that releases cyanide when eaten. Gasping, excitement and prostration are common symptoms.
 Chinaberry  Leaves and fruit Gastric, intestinal, paralysis, respiratory
 Chokecherry  Leaves and pits
 Clematis  Seed and young plants Gastric, nervous system, depression
 Daphne Shrub  Berries Fatal. A few berries can kill a child.
 Elderberry  All parts, especially roots Children have been poisoned by using pieces of the pithy stems for blowguns. Nausea and digestive upset.
English ivyLeaves and berriesNervous system, respiratory
 Golden Chain Tree  Bean-like capsules in which the seeds are suspended Severe poisoning. Excitement, staggering, convulsions and coma. May be fatal.
 Holly (Yaupon)  Berries Gastric, intestinal
 Hydrangea  Leaves, buds  Gastric, intestinal
 Jasmine  Berries Fatal. Digestive disturbance and nervous symptoms.
 Lantana Camara (Red Sage)  Green berries Fatal. Affects lungs, kidneys, heart and nervous system. Grows in the southern U.S. And in moderate climates.
LaurelsAll partsFatal. Produces nausea and vomiting, depression, difficult breathing, prostration and coma
 Mountain laurel  Leaves, twigs, flowers Gastric, paralysis, convulsion
 Oaks  Foliage, acorns Affects kidneys gradually. Symptoms appear only after several days or weeks. Takes a large amount for poisoning.
 Wisteria Vine  Seeds, pods Mild to severe digestive upset. Many children are poisoned by this plant.
 Yew  Berries, foliage Fatal. Foliage more toxic than berries. Death is usually sudden without warning symptoms.

Credit for information –

Credit for photos:

Hopefully you have found this basic guide on how to set up a transpiration bag to collect water useful if you were unfamiliar with this cool skill to get vital water if you are in dire straits.

As always, your opinions and comments are welcome below 🙂

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