Solar Still Survival Guide: How to Purify Water in Dry Environments

Why Learn to Make a Solar Still?

In survival situations, especially in dry environments like the desert or arid backcountry, finding clean drinking water can be a major challenge. That’s where knowing how to make a solar still can be a life-saving skill.

A solar still uses the sun’s heat to distill and purify water from soil, vegetation, or even salty or contaminated sources. It's a low-tech but highly effective method of water purification that requires minimal tools and taps into the natural process of evaporation and condensation. This method pairs well with other survival water techniques like boiling vs filtering when deciding the best approach based on your conditions.

This guide will walk you through exactly how to build a solar still, explain when and why it works, and give you practical tips for maximizing water output in tough conditions. Whether you’re preparing for survival or just want to expand your bushcraft knowledge, this technique is one of the most essential you can master.

What Is a Solar Still and How Does It Work?

A solar still is a simple device that captures evaporated moisture from a heat source — typically the sun — and condenses it into clean drinking water. It relies on basic science: when the sun heats up wet soil or plant material, moisture evaporates. If you trap that moisture under plastic, it will eventually condense on the underside of the plastic and drip into a container placed underneath.

The beauty of this method is that it can purify a wide range of contaminated or non-potable sources, including saltwater, polluted groundwater, or even urine (in extreme cases). The end result is distilled water that’s safe to drink. If you need to find water sources before building your still, brush up on how to locate water in the wild — it’s a foundational survival skill.

Materials You Need to Make a Solar Still

You don’t need much to build a solar still, and some of what you do need can be scavenged in the wild. You’ll need a large piece of clear plastic sheeting, a container or cup to catch the water, a digging tool or your hands, and optionally a piece of tubing for drinking or drawing water out without disturbing the setup.

Choose a sunny spot with damp soil or green vegetation. If you’re in the desert, early morning is best to capture moisture still present from the night. Avoid shaded or rocky ground that won't heat up easily.

Step-by-Step: How to Build a Solar Still

Start by digging a hole about two feet wide and one foot deep. Place a container in the center to collect the water. If you have vegetation or non-potable water like saltwater or urine, pour or place it around the container inside the hole.

Next, lay your plastic sheet over the hole and secure the edges with rocks or dirt. Drop a small stone in the center of the plastic so it forms a slight cone shape, pointing directly above your container. This allows the condensation to run down the underside and drip into your cup.

Now, wait. As the sun heats the still, water vapor will rise from the moist materials and condense on the plastic. After a few hours, you should start seeing water droplets collect and fall into the container. Depending on the heat, soil moisture, and plastic size, you could collect up to a quart of water per day from a single still.

Tips to Maximize Solar Still Efficiency

If your solar still isn’t producing enough water, it’s smart to combine it with other wilderness hydration methods. Try collecting rainwater using simple tarp or leaf setups, or even learn how to harvest dew and condensation from morning surfaces. These small gains can keep you hydrated when every drop counts.

You should also know how to locate natural water sources in dry terrain — even deserts can hold hidden moisture in underground pockets or beneath certain plants. For best results, pair your solar still setup with strong navigation skills, so you can scout better locations for building them in open sun and damp ground.

Final Thoughts on Solar Still Water Purification

When you’re far from civilization and desperate for drinking water, knowing how to purify water with a solar still could be what keeps you alive. It’s a dependable and low-effort way to get safe water in hot, dry regions where streams and lakes are scarce or undrinkable. Practice building one before you need it — so that if a survival situation ever arises, you’ll already know exactly what to do.