======Salt Water Purifier======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Categories:** {{$demo.categories}}
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**Alternative titles:** Homemade Desalination Device
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====Summary====                   
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====Procedure====  
  - Fill a large bowl with about 3 cm (1 inch) of warm water.  
  - Add salt and stir until it dissolves, creating salt water similar to seawater.  
  - Place a smaller empty bowl inside the large bowl, ensuring it sits above the salt water but is still surrounded by it.  
  - Cover the large bowl tightly with plastic wrap and tape it around the edges to seal it.  
  - Place a coin or small pebble in the center of the plastic wrap so that it dips slightly toward the middle above the small bowl.  
  - Put the setup in a sunny spot (or under a warm lamp) for several hours.  
  - Observe droplets forming on the underside of the plastic wrap and dripping into the smaller bowl.  
  - After several hours, carefully remove the cover and taste a small amount of the collected water—it should be fresh.



====Links==== 
Salt water purifier - The Experiment Archive: 
{{youtube>PZ4dWZXGfi8?}}\\

Science Is Everywhere: Fresh Water from Salt Water — Desalination - Children's Discovery Museum of San Jose: 
{{youtube>3h49i1iDNP4?}}\\

📄 Salt water purifier - Science Buddies: [[https://www.experimentarchive.com/experiments/salt-water-purifier/]]\\


====Variations====
  * Use bowls of different sizes to test how surface area affects the amount of collected water.  
  * Try deeper or shallower salt water levels.  
  * Add food coloring to the salt water to visualize that only clear water evaporates.  
  * Conduct the experiment indoors with a lamp instead of sunlight.  
  * Add soil and grass to simulate natural evaporation from the ground (do not drink the water from this version).



====Safety Precautions====
  * Do not drink the salt water or any unpurified samples.  
  * If adding soil or organic materials, do not consume the collected water.  
  * Handle glass bowls carefully to prevent breakage.  
  * Conduct the experiment in a stable, sunny, and safe area away from small children or pets.




====Questions to Consider====
  * Why does the water that collects in the small bowl not taste salty? (Because when salt water evaporates, only water molecules turn into vapor; the salt and other impurities remain behind.)  
  * What role does the coin play on the plastic wrap? (It creates a low point where condensed water can drip into the center bowl.)  
  * How is this process similar to the natural water cycle? (It involves evaporation from a liquid surface, condensation on a cooler surface, and collection as precipitation.)  
  * What factors affect how quickly water evaporates? (Temperature, light intensity, surface area, and air movement.)  
  * How could this technique be useful in real life? (It models solar desalination, a method used in survival situations and water purification systems in arid regions.)