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“Water, water, everywhere, And all the boards did shrink; Water, water, everywhere, Nor any drop to drink.”
These famous lines from Samuel Taylor Coleridge’s 1798 poem “The Rime of the Ancient Mariner” remind us of one of the cruel ironies about living on Planet Earth. Although water covers 75 percent of our planet, more than 97 percent of it is undrinkable salt water.
Consuming large amounts of salt water is toxic to the human body. Experts estimate that for every gallon of salt water you drink, you’d need to drink a least a gallon of fresh water to allow the kidneys to do the job of flushing the salt out of your body.
Since drinking salt water also makes you thirstier, you can see that it would be a never-ending battle to stay hydrated. Severe dehydration causes the body’s vital organs to shut down.
As drought continues to ravage much of the world — including the Western United States — and aging water infrastructures deteriorate, broad efforts to desalinate water efficiently and economically are more critical than ever. However, at a time when natural and human-made disasters that can impact our water supply are on the rise, knowing how to desalinate water on a smaller scale is an essential survival skill.
In this article, we’ll take a look at the three primary methods for desalination – the process of removing sat and other minerals from water – for survival purposes.
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Solar Desalination
Using the power of the sun to remove the salt from water is a natural first choice for creating potable water. One relatively easy method is to create a solar still.
To make a basic solar still, you need to dig a hole in the ground in a location that gets plenty of direct sunlight. Then, place some leaves and other vegetation in the hole to add extra moisture before pouring saltwater into the hole.
Next, place a cup, jar, or bowl in the middle of the hole before securely covering the entire hole with a sheet of plastic. This video shows the process.
You can learn a smaller scale version of this solar distiller method by watching this video:
Here are the steps:
1. Place salt water in a bowl so that it is about two-thirds full.
2. Place a smaller cup into the center of the bowl, being careful not to allow any of the salt water to enter the cup. Make sure the edge of the cup is well above the salt water level.
3. Cover and seal the rim of the bowl with sturdy plastic wrap, ensuring there are no gaps, slits, or holes in the wrap.
4. Place a small rock or other small weight on the wrap surface right above the cup. The idea is that the weight will cause the plastic wrap to dip a bit towards the center, allowing the fresh water to drip into your cup. However, if the weight is too much and damages the plastic, you’ll need to start over.)
5. Set the bowl in direct sunlight for several hours.
As the sun heats the water, condensation will begin to form underneath the plastic wrap. Then, drops of this fresh water will slowly drip into the cup. You can repeat this process as often as needed.
Evaporation Desalination
This desalination method also uses heat to cause evaporation, but it has another energy source. You can see it demonstrated in this video:
Here are the steps to follow for this evaporation distillation method:
- You’ll need a metal bottle and a cork (or rubber stopper) that fits its opening. Make a hole in the top of the cork that allows copper tubing to fit.
- Fill the bottle about two-thirds of the way with salt water.
- Place the tubing through the cork until it reaches the bottom of the cork. Then, push the cork (with the tubing attached) into the top of your bottle.
- Run the other end of the tubing to another shorter bottle.
- Place the first bottle over a source of moderate heat until the water starts to boil and steam begins to form.
The steam will through the tubing and convert to fresh water droplets as it enters the new container.
Pot and Stove Desalination
With this method, you will need a heat source, a large lidded cooking pot, and a Pyrex glass cup or metal cup that can fit inside the lidded pot. You’ll also need copper tubing and some couplers. Check out the process in this video.
- Pour salt water into the pot, leaving room near the top.
- Carefully place the cup into the pot, making sure no salt water gets into the cup.
- Pace the pot on your stove over moderate to low heat until you have a slow boil.
- Pace the lid over the pot in an upside-down position so that the center handle is directly over the cup. Make sure the upside-down cover is snugly fit over the pot so that the steam does not escape.
- The steam that rises to the lid will change to fresh water droplets that drop into the cup.
In each of these desalination methods, use caution when removing the water. First, the water will be hot, and second, you don’t want to risk getting any of the surrounding salt water into the newly desalinated water.
There also are some commercial products available that use these desalination techniques. For example. the Aquamate Solar Still Emergency Water Purification Inflatable Kit uses the principles of the first method we listed. And the Megahome Countertop Water Distiller is a product that utilizes the pot and stove method.
All of the methods work, but you’ll notice that they only provide a small amount of water for personal use. They also take some time and patience.
Since the human body requires 11 to 15 cups of fluid each day, these ideas are meant for emergency survival purposes. However, since humans can survive for only about three days without water, knowing how to desalinate even small amounts of water could very well save your life.
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