Building Simple Solar Stills for Obtaining Freshwater from Ocean Saltwater

Solar stills are an effective and sustainable method for purifying water, particularly in areas where access to clean drinking water is limited. These devices utilize solar energy to distill water, making them ideal for converting ocean saltwater into freshwater. Here’s a guide on how to build simple solar stills for freshwater production.

Basic Principle of Solar Stills

Solar stills work by harnessing the sun’s energy to evaporate water, which then condenses and collects as freshwater, leaving impurities behind. This process mimics the natural water cycle of evaporation and condensation.

Materials Needed

– Transparent Cover: Glass or clear plastic sheet
– Container: Basin or pan to hold the saltwater
– Collector: A smaller container to collect the distilled water
– Weight: Rock or sand to create a sag in the plastic sheet
– Sealing Material: Dirt or sand to seal the edges

Simple Solar Still Designs

1. DIY Solar Still Using Household Items

This method is great for demonstrating the principle of solar distillation and can be easily set up at home.

– Materials: Glass bowl, small glass jar, salt, water, clear plastic wrap.
– Instructions:
1. Fill the bowl with saltwater.
2. Place the jar in the center of the bowl without touching the saltwater.
3. Cover with plastic wrap and secure with a rock in the center.
4. Place in sunlight and collect the distilled water in the jar after several hours[2].

2. Pit Solar Still for Survival Situations

This design is useful in wilderness survival scenarios where materials are limited.

– Materials: Shovel, clear plastic sheet, container (e.g., jar), rock or sand.
– Instructions:
1. Dig a hole about 2 feet by 2 feet and 1.5 feet deep.
2. Place the container in the center of the hole.
3. Cover the hole with a clear plastic sheet and seal the edges with dirt or sand.
4. Place a rock or sand in the center to create a sag.
5. Wait 24 to 48 hours for water collection[3][4].

3. Box-Type Solar Still

This design is more structured and can be built using readily available materials like wood and glass.

– Materials: Wooden box, glass panes, black paint, insulation material.
– Instructions:
1. Build a wooden box with a sloping top.
2. Paint the inside black to absorb sunlight.
3. Place a glass pane on top at an angle.
4. Add saltwater to a pan inside the box.
5. Collect distilled water as it condenses on the glass and runs into a collection tube[1][5].

Advantages of Solar Stills

– Energy Efficiency: Uses solar energy, reducing reliance on electricity.
– Low Cost: Can be built using inexpensive materials.
– Portability: Suitable for both home use and wilderness survival.
– No Moving Parts: Requires minimal maintenance.

Limitations

– Low Output: Typically produces small amounts of water per day.
– Dependence on Weather: Requires direct sunlight to function effectively.

Conclusion

Solar stills offer a simple, eco-friendly solution for purifying ocean saltwater into freshwater. While they may not produce large quantities of water, they are ideal for emergency situations or small-scale use. By leveraging the sun’s energy, solar stills provide a sustainable method for accessing clean drinking water in areas where it is scarce.

A List of Desalination Methods