Water from Condensation

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Moisture can be extracted from the most unlikely of places because of Evaporation and Condensation.
This process is happening around us all the time. For example, nature uses evaporation to make clouds and condensation to make rain.

For the survivor, this can be a double edged sword. Humans experience fluid loss through breathing, talking, sweating, digestion and excrement but guess what; we are not alone. Most living things, experience fluid loss in this way and the survivor can harness this to increase their chances of survival. Heating anything which holds water will cause the water to evaporate.

In fact, for the most part, water just keeps on cycling around being consumed by all sorts living things, serving it’s purpose and then being released back into the ground or air as evaporation.

This trick is in catching it so that it condenses and provides you with a decent amount to drink.
Thankfully, with some knowledge the number of ways to collect this are limited only to your imagination.

Evaporating water and collecting the condensation will remove any impurities so therefore this process makes it possible to extract fresh, drinkable water from urine, seawater, contaminated water, poisonous liquid and sap, mud, clay etc.

The survivor will often be presented with the situation where the only liquid they have access to is unfit for drinking such as Sea Water, Urine, Contaminated or Poisonous Water and Suspect Plant Sap. Thankfully, by distilling these liquids, in a Still, the survivor can extract water which is fit to drink. The same method can be used to extract drinkable liquid from substance such as Earth, Foliage, Blood, Feces etc.

Although all stills work on the same basic principle of using heat to evaporate the water content from a substance, catching the water vapor and cooling it to condense the water droplets before channeling this into some form of container for drinking, there are many different ways of approaching stills depending on where you are and what materials & heating/cooling options you have available.

Some of the methods for creating a still are listed, in detail, below. There are also inflatable solar survival stills on the market which would be an ideal piece of kit to keep on a boat.

If you have fire as a heat source, the still can be a very efficient method of desalination of seawater and or decontaminating of water; or extracting water from poisonous liquid such as milky sap.

The tricky bit, when using fire as a heat source, is catching the water droplets as they evaporate. This can be done with a large plastic bag, tarpaulin or hoochie (folded into a cone shape) provided that the fire is low intensity (so as not to melt the bag or tarp).

The method for this is to make a tripod by lashing three 5-6ft sticks together and positioning it over the top of the fire. The plastic bag is then placed over the top of the tripod creating a cap.

Before placing the bag, or tarp, over the tripod, the opening edge of the bag/tarp must be folded back up, inside the bag so that it creates a catchment for the condensed water to pool.

Put the pot or improvised container of liquid on the fire and wait for the water to pool.

An alternative could be to use a
large piece of fabric instead of a plastic bag. Once the fabric is saturated, replace if with a dry piece. Let the saturated piece cool for a minute or two before wringing the water out into a container to drink.

You could also use a large flat leaf (e.g. A banana leaf) fashioned into a cone shape and pinned with a stick to catch the water vapor as it evaporates. A smaller tripod (20-30 cm) could be placed in the water container which would suspend the leaf cone above. Bamboo split in half lengthwise could be laid around the fire to catch the condensed water as it drips off the edges if the leaf cone.

The solar still method involves using heat from the sun to extract drinkable water from the ground, mud, foliage or feces via condensation.

Dig a hole in the ground about knee to thigh deep.
Place a container in the center of the hole and place cut vegetation around the container (you can leave out the vegetation if you don’t have any. So long as the ground is damp in the hole moisture will be drawn from the ground).

Cover the hole with a piece of plastic, weight it down with rocks and seal around the edges with sand, dirt, stones or mud. Place a small stone in the center of the plastic, above the container. Leave for a few hours.

If possible, you can place a piece of hose in the water container before sealing the hole so that you can drink the liquid without disrupting the still.
illustration of a solar still

 

 

Inflatable Emergency Solar Still

There are a number of inflatable solar survival stills on the market which are an ideal piece of kit for boats and life rafts and are highly recommended for any voyage out to sea. Essentially they are an inflatable pyramid which uses evaporation and condensation caused by the sun to convert seawater into fresh drinkable water. These pack up nice and small for easy stowage and are available from most fishing and boating stores.

This method of collecting water uses evaporation and condensation to draw drinking water from a branch of a tree.

Place a plastic bag over the end of a branch (pick a branch with as much foliage as possible) and tie the opening of the bag tightly around the branch of the tree to seal it off.

Ensure that the branch is not pushed too far into the bag so that it is jammed up against the bottom of the bag as this may inhibit the condensation running down to the bottom of the bag.

Leave this for several hours. The sun will heat up the air inside the bag and this will cause the moisture in the tree branch to evaporate. The water droplets will condense on the inside of the bag and run down to the lowest point in the bag creating a small reservoir of water which is good to drink.

Set up as many of these as you can so that you get a good supply.

illustration of a branch still

Like the solar still, the sweat bag still method can be used to draw drinkable water from foliage or contaminated water but without the effort of digging a hole.

Place a plastic bag (on it’s side) on the ground and brush the dirt off some stones and place them into the bag to form a small platform.

Place leaves, vegetation offcuts or foliage on top of the platform (this will keep the foliage up out of any water which pools at the bottom) and prop the top of the bag up with a stick to form a large hollow space filled with air. Ensure that you pad the top of the stick with fabric or a rock to stop it tearing a hole in the bag.

Seal the opening of the bag by tying and then just leave it to sit in the sun for a few hours.

The sun will heat the air inside causing the moisture in the foliage to evaporate and condense on the inside of the bag. The condensation will trickle down the inside of the bag and pool at the bottom.
This water will be good to drink.

You can also try substituting the foliage with a container of mud or urine.



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