It is warm outside and kids are going to the beach (where there is salt water) and the pool. Some kids may notice that they float better in salt water than in fresh water. After doing this experiment, your child will know why this occurs. Explore the difference in density between salt water and fresh water with this easy experiment. 

Let’s Get Started!


  • 2 Glasses of Water
  • Salt
  • Spoon
  • Food Coloring
  • Ice
Materials for Salt and Fresh Water Experiment


  • Place a few ice cubes into one glass of water
Placing ice in fresh water
  • Add a few drops of food coloring into the ice water.
Adding green food coloring into the ice fresh water.
Observing how the green food coloring disperses into the fresh water.
  • Add several tablespoons of salt to the other glass of water and stir so it dissolves.
  • Add some ice cubes to the salt water glass.
Pouring salt into the other glass of fresh water
  • Add food coloring to the salt water and see what happens.
Adding food coloring to the salt water
The salt is causing the food coloring to float.
  • Compare the food coloring in the fresh and salt water.
Observe the difference.

Why it Works:

  • Saltwater is denser than fresh water because the sodium chloride is dissolved in it.
  • Specific amounts of salt water is heavier than the same volume of freshwater.
  • When salt is dissolved in water, like at the ocean, the salt adds to the mass of the water.
  • The salt makes the water denser than it would be without the salt.
  • When salt is dissolved in water, as it is in ocean water, it adds to the mass of the water and makes the water denser than it would be without salt. Because objects float better on a dense surface, they float better on salt water than in fresh water.

Have fun with this experiment!

Don’t forget to check our two books, Teach your Toddler to Read Through Play and Fun and Easy Ways to Teach your Toddler to Write.

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20 thoughts on “Salt and Fresh Water Experiment

  1. We LOVE experiments like this. This one looks fun and easy to do with things I already have. Thanks!

    1. OH great! I love easy and fun experiments as well. I hope your kids enjoy it. Thank you for commenting Charlene!

    1. Oh great! I hope your girls have fun with this! Thank you for commenting.

  2. This is so easy. My girls would love it. Saving it for my summer activities. Thanks for sharing.

    1. No problem! I love fun and easy activities! Thank you for commenting.

  3. Such a great experiment! We did a similar freshwater/saltwater experiment like this (but with eggs), with our science camp kids, and it was a hit!

    1. This would be cool to do with eggs. My son and I will try this soon. Thank you!

  4. Hello! I LOVE this for my students, you wouldn’t happen to have a lab sheet to go along with it, would you? Thank you!

    1. Hello Nichole, I am sorry. We don’t have a lab sheet for this experiment. Thank you for your comment. I am glad you like this experiment.

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