Water Desalination. You need fresh water to survive!

I thought about the idea for awhile after hearing about being stranded on a deserted island on a TV show. It went along the lines of what could you eat? I thought to myself, what would you drink?

I could spend hours researching water desalination techniques, and build a thread explaining the techniques to make saltwater safe to drink, so I thought instead, hey, let's throw this one out to the ATS crowd. On that premise, we are bound to learn many practical techniques to do just that.

Many scenarios come to mind where everyone should know one trick or another.

1. You are on a plane, and it crashes on a deserted island, with no resources available. What's the means by which to get freshwater (of which you have none), from the sea, (which is all around you) and have enough water to survive on?

2. Cruise ship, same scenario, it sinks and you wash ashore somewhere. How do you get freshwater to drink until the rescue crews arrive?

3. The Collapse occurs, chaos all around, yet you are near the ocean, but cut off from supply lines. You need to make your own water to drink from the sea.

I did a tad of research, and rather than go in-depth, I chose to see what ATS comes up with. Here's a bit of info to get you started:

Thirsty? How 'bout a cool, refreshing cup of seawater?

No, don't take us literally! Humans cannot drink saline water. But, saline water can be made into freshwater, which everyone needs everyday. The process is called desalination, and it is being used more and more around the world to provide people with needed freshwater. Most of the United States has, or can gain access to, ample supplies of fresh water for drinking purposes. But, fresh water can be in short supply in some parts of the country (and world). And, as the population continues to grow, shortages of fresh water will occur more often, if only in certain locations. In some areas, salt water (from the ocean, for instance) is being turned into freshwater for drinking.

Here are our parameters for saline water:

Fresh water - Less than 1,000 ppm
Slightly saline water - From 1,000 ppm to 3,000 ppm
Moderately saline water - From 3,000 ppm to 10,000 ppm
Highly saline water - From 10,000 ppm to 35,000 ppm
By the way, ocean water contains about 35,000 ppm of salt.

The worldwide need for freshwater:

The scarcity of fresh water resources and the need for additional water supplies is already critical in many arid regions of the world and will be increasingly important in the future. It is very likely that the water issue will be considered, like fossil energy resources, to be one of the determining factors of world stability.

Bold mine.

Okay, so my OP doesn't need to be so fantastical such as a plane crash on a deserted island. There already a freshwater shortage, and the demand is overwhelming the supply. It appears to be a tenuous balance worldwide.

Source: USGS.

So, ATS, feel free to respond. We need freshwater, from salt water, in a survival scenario. Solutions?

Easy, take a large pot.
Pour the sea water.
Make a fire.
Boil the water.
Trap the evaporation with either hard plastic, sheet metal, poncho, or whatever.
Make sure the evaporated water can drip down into a bucket aside from the boiling water,..... and presto.
You have Clean/Fresh water.

When the salt water has finished boiled you will have a nice fresh supply of salt to cook with.
Too Easy.

Originally posted by magestyk7
Easy, take a large pot.
Pour the sea water.
Make a fire.
Boil the water.
Trap the evaporation with either hard plastic, sheet metal, poncho, or whatever.
Make sure the evaporated water can drip down into a bucket aside from the boiling water,..... and presto.
You have Clean/Fresh water.

When the salt water has finished boiled you will have a nice fresh supply of salt to cook with.
Too Easy.

D@M YOU! you beat me to it.

Yeah it's not rocket science. Water evaporates...salt doesn't. All you have to do is not DESALINATE but DISTILL the water. Which you pointed out how it works.

Boil water > capture water > use sea salt to flavor food, mmmmm.

Originally posted by magestyk7
Easy, take a large pot.
Pour the sea water.
Make a fire.
Boil the water.
Trap the evaporation with either hard plastic, sheet metal, poncho, or whatever.
Make sure the evaporated water can drip down into a bucket aside from the boiling water,..... and presto.
You have Clean/Fresh water.

When the salt water has finished boiled you will have a nice fresh supply of salt to cook with.
Too Easy.

You forgot one thing in a survival situation dont drink large quantities of distilled water in will rob your body of minerals.You can take some of the salt and put it back in the water or actually place rocks in bucket that collects water. On a deserted island sand can work as well to filter the water to drink it will capture the salt but allow the water to flow through and will not remove minerals.

Originally posted by guesswhoyouknew

Originally posted by magestyk7
Easy, take a large pot.
Pour the sea water.
Make a fire.
Boil the water.
Trap the evaporation with either hard plastic, sheet metal, poncho, or whatever.
Make sure the evaporated water can drip down into a bucket aside from the boiling water,..... and presto.
You have Clean/Fresh water.

When the salt water has finished boiled you will have a nice fresh supply of salt to cook with.
Too Easy.

D@M YOU! you beat me to it.

Yeah it's not rocket science. Water evaporates...salt doesn't. All you have to do is not DESALINATE but DISTILL the water. Which you pointed out how it works.

Boil water > capture water > use sea salt to flavor food, mmmmm.

No damn you you both beat me to it! I learned that in my Smart kid summer school in "The Voyage of the Mimi"!

reply to post by magestyk7


What if you don't have the large pot? What if you don't have fire?

You are assuming a lot. Think hardcore survival. No man made objects.

Now, re-work how easy it is. Can you?

I made a quick little graphic here to help....



That is how I was taught to do it. The plastic wrap entirely covers and closes in the coffee can or whatever is being used. Any container will work, but the smoother the better and metal is preferable to speed the process for collecting heat. Arrange everything like the graphic shows with some small pebbles to hold the wrap in a point over the drinking cup. Place the whole thing on a nice rock in the sun and wait patiently. Remember to boil AFTER this.This works to remove salt and other heavy contaminates but I wouldn't drink questionable water after only doing this much. Bad water is a fatal condition in a true survival situation so over-caution pays.

* Added Note.. If fire isn't possible or practical, use bleach for the final purification step. Might not be a bad idea anyway, actually...since boiling actually causes the loss of some precious water you worked so hard for.

Instructions for proper use of SMALL amounts of Bleach to purify water

This is the Survival Forum, so use your brains. If you really needed fresh water from saltwater, how could you reduce the salinity to make it drinkable without dehydrating yourself in the process?

From scratch.

Using the sand as a filter sounds like a great idea to me.

reply to post by Wrabbit2000


You won't find a coffee can on a deserted isle. Sure, you have the technique, but how can you modify that with only natural materials?

Hypothetically, there are twenty survivors of your plane crash on the deserted isle. Will your technique produce enough freshwater to keep them all hydrated?

That's twenty coffee cans, twenty plastic sheets, and twenty cups to collect the condensate. You don't really have any of those. How can you improvise that technique?

Star for the basic diagram, but think outside the box.

reply to post by Druid42

Well, a little imagination is required and the adaptations are entirely too based in the specific circumstances...but a larger scale of this can be done by digging a small pit. Whatever can be found or adapted (shells of a Coconut, Pineapple or anything else capable of holding water) is placed in the center. the cover to condense and drip is a challenge..and again, improvising is hard to guess depending on circumstances but I'd attempt using large palm leaves or a combination of smaller things... The man made material is the Deluxe model and this rather mickey mouse system is the "when nothing else can work" ....but it's possible to scale this up and down as needed.

^^^ Forgive me for not being more precise..I'm going by the memory of scout lessons half a lifetime ago on the "outback jack" version.

Can weave palm leaves together strap them very tight to the bottom of a hollowed out tree trunk then poke very fine holes in the weave. Pack sand into the top can use it as a natural filter, then just pour through and make sure you have something to catch the water. Very easy to improvise if you had some other man made items with you as well (plastic sheets, Cans, etc.). But this can be made with items straight out of nature, and with rocks as tools.

reply to post by Druid42


are we allowed to cannibalize parts from airplane/boat?
lots of plastic, glass, and pipes IMO

1. Approach sea water container. (Ocean)

2. Catch Fish with bare hands.

3. Suck out an eyeball.

4. Swallow.


You are now a bit more hydrated than you were.

reply to post by Brandon88


You, my friend, get the original thinker award, plus you survive. Hopefully, the rescue teams arrive soon, but it appears you could desalinate your own water, and teach others. Too salty for long term survival, but you could get by with that design.

Any other designs? Anyone?

Think sunlight and evaporation.

maybe dig a hole in low areas behind sand dunes as fresh water collects there, walk through grass in early morning to catch dew around ankles, find hollows in trees or bedrock for catchment spots, cliffs or caves near oceans may have springs breaking through, use distill method with any greenery and plastic cover, flesh of fish can be sqeezed through cloth for liquid or thirst, bamboo, vines and tree roots broken open seep their juice, coconuts would be great too. lol

reply to post by Druid42


Dude are you serious?

1st, if you dont know how to make a fire,.... then you pretty much DONE! Fire is 'essential' in survival.

2nd, I dont know about you but I'm not planning to teleport to a tiny Island on the pacific like the Terminator with nothing on me. Let me explain. I'm in the U.S. and therefore I dont care what planetary events/catastrophe takes place. I'll still be here(If I survive) and I'll guarantee I'll find simple materials scattered everywhere to boil water with a FIRE!

So your logic is flawed.

reply to post by Druid42


You bring up several scenarios. Considering the odds of someone crashing on a small island... I'll rule that one out for myself. Cruise ship or personal sailboat... any ocean going vessel should be well equipped with a proper ditch bag including a portable desalinator like the Katadyn survivor www.katadyn.com...

In the event of a collapse type situation and you live in a coastal area, you should take some daily life lessons from the people of Bermuda. In Bermuda, it is common for people to store and use rain water collected from all roofs into a network of cisterns.

Drinking Water

The tap water in Bermuda is generally considered safe to drink. Bermuda relies almost entirely on its annual rainfall to provide the country's entire source of water, although some desalination of seawater is taking place. Houses usually rely on their own rainwater collection system or have a combination of rainwater (for cooking and drinking) and piped or delivered water (for showers, toilets, and laundry).

hamilton.usconsulate.gov...



I've learned a little from Bermuda. Fortunately, I live near the Great Lakes and many natural streams However, I still collect rain water in a series of three barrels all interconnected. It gives me a ready supply should I need it. I can just pour it into my Berkey filter and its ready to go for cooking and drinking...

Dig inland until you hit the spot where Momma Nature has already secured fresh water for you and her other children.
Easy.