How To Build A Solar Still For Survival


How To Build A Solar Still For Survival

I think by now we all know how important it is to have access to fresh, clean drinking water. In fact, you can only survive 3 days without water, which makes it more essential than food.  But how will you find clean water when SHTF? It won’t be as easy as turning on the tap or heading down to the store for a case of bottled water.  You’re going to need to learn how to purify your own H2O. Preferably, you’d have multiple purification methods in your bug out bag (you do have one of those, right?), in case one fails or isn’t possible in the situation.

You don’t want to solely rely on one source like a LifeStraw or purification tablets either because these have limited uses and can get stolen or broken.  Obviously, filters and tablets are the easiest ways of making your own clean water but my favorite method involves nothing more than trash, dirty water, and the sun.  That’s right, I’m talking about a solar still.  It works similar to a whiskey still but in this case we won’t be making any white lightning, we’ll be distilling pure H2O.  And you won’t need a heat source other than that great ball of fire burning above our heads.  Think of a greenhouse that lets light in and traps the heat. That’s what we’re going to make but we’re going to use that heat to create condensation.  It’s simple to make and uses trash that you can find nearly anywhere. I’ve honestly been in the woods before and found all three “ingredients” before.

How To Set Up A Solar Still

Reference the image above and more specifically the video below for the instructions below.  

Step 1: Find a clear plastic water bottle big enough to hold a can with a little extra room, a black/dark colored can, and some dirty, unfiltered water*.

The reason for picking a dark colored can is that it will attract more heat so the darker the better. But any color will work.

When you’re picking a water bottle, try to choose one that just fits around your can rather than tall or wide so the heat gets more concentrated and won’t dissipate in the excess room.

Note: Unlike other filtration methods, you don’t need to strain out larger detritus and debris first.  Don’t waste calories and gear doing unnecessary steps.

Step 2: Cut the bottom off of the water bottle so the can will be able to fit inside of the larger water bottle and fold the inner edges of the bigger water bottle up so they can collect the clean water.  Kind of like a tiny moat for your can.

Step 3: Cut the top off the can and fill it with the dirty water.

Step 4: Place the can inside the bottle and put the still somewhere with direct sunlight.

You can set it up outside on the ground or a table. It would also work inside in a sunny window but probably not as well.  Obviously, keep it out of areas with high wind because if it blows over, the dirty water will spill into the clean water and you’ll have to start all over.

Step 5: Wait.

The heat from the sun will cause the dirty water to evaporate (the dark can enhances this effect) and moisture droplets will build up on the inner walls of the bottle.  As the number of droplets builds, the water will run down the sides of the bottle and collect at the bottom in your “moat”.

Step 6: Tap the bottle to get all that good, clean water off the walls of the bottle and into your moat.

Step 7: Enjoy your fresh water!

If you’re more of a visual learner like I am, here is a great video explaining the process:

A benefit to using a water bottle in this process is that when you are done, you can unscrew the cap and drink from it like a regular water bottle or use it to easily pour your newly clean, fresh water into a storage container without wasting a drop.

Admittedly, this method is not the most efficient process. It takes a quite a bit of time and it does NOT produce a massive amount of water. But it is better than nothing and is relatively easy to construct and may be enough to help stave off dehydration in a pinch.  Also, it is passive and easy to do even when you have no supplies with you (if you are able to find some trash).  If possible I’d recommend setting up multiple stills while you’re waiting for your first ones to “brew” since they’re so easy to make.

Alternative Method To Build A Solar Still

Of course, this is just one type of solar still.  Once you understand the concept, there are a variety of ways to use it.  If you find yourself in the desert without any dirty water to purify, here’s another method:


Image Credit:

Step 1: Dig a large, wide hole about 4 feet wide and 2-3 feet deep.

Step 2: Put a large container (think coffee can) in the center of the hole.

Step 3: Cover the hole with a plastic sheet, securing it to the rim of the hole. It’s important to make sure that the edges are secure and no moisture can escape.

Step 4: Place a medium sized rock in the center, directly over the container (enough to weight down the sheet but not rip it).

Step 5: Wait for the heat to pull the moisture from the ground and then it will evaporate up and collect in droplets onto your clear plastic sheet.  Gravity will then pull the water down to the center of the sheet at the pebble and drip into your container.

Step 6: Carefully tap the sheet to get the extra water droplets to drip into your container.

Step 7: Carefully peel the plastic sheet back and remove the container and Enjoy!

Note: You can also put tubing into the container and run it out under the plastic sheet like a really long straw so you don’t have to break down your still to enjoy clear, fresh agua!

One additional tip to make this method more effective is to put some green vegetation inside the still area but not in the collection container.  This process will pull moisture from the vegetation and the surrounding ground as well.  Furthermore if you dig the hole in an area that has somewhat moist ground this will help as well. Lastly, you can also urinate around the edges of the hole and the process will pull the moisture (but leave the bad stuff) from the urine as well.

Reality Check: While this method can work effectively if you have a moist hole, you are using some vegetation, etc. It typically does not produce very much water at all if if is constructed with just a dry hole. In fact, constructing one of these in a dry hole is typically not worth the expenditure of calories and water that it takes to dig the hole in the first place. The first method described above is much more productive than this alternate method.

This has been a collaborative post between JJ Johnson the author of and Evan Michaels who is a writer for Know Prepare Survive, a survival site that covers prepping, homesteading, tactical gear, bushcraft skills, and more. Be sure to check out Evan’s latest post on the best tactical flashlights for preppers.


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