Have you ever wondered why freshwater fish can’t live in the ocean and how saltwater fish survive in saltwater? So did we! In this desalination science project, we investigated how saltwater fish survive in the ocean.
To illustrate how saltwater fish filter salt from their bodies, we conducted our own water ocean science experiments and made our own water distiller.
How to Do the Desalination Science Project
If you want to know how to remove salt from water, follow along with these directions for setting up the desalination science project!
How Saltwater Fish Live in the Ocean
One day recently, the kids and I had a discussion about what allows saltwater fish the ability to survive in the ocean and whether freshwater fish could survive there.
Monkey thought that perhaps saltwater fish drank the saltwater and needed it to survive. This sparked an investigation of how saltwater fish survive in the ocean.
We read this lesson about how fish can stay alive in saltwater, and found that fish all fish filter the salt out of the water surrounding them. Most fish remove the excess salt through their kidneys, just like humans (but much more efficiently), but sharks have a chemical called urea that helps prevent salt overload in a shark’s body.
Learn how to do the cartesian diver experiment here.
The shark has a special gland that removes salt through the digestive system.
Monkey wanted to know if it was possible for humans to remove salt from water, which sparked a discussion and investigation of how to remove salt from water. We learned that a process called “desalinization” is how salt is removed from water.
The simplest way to remove salt from water is to evaporate the water and collect it in a new container through water distillation, which leaves heavier salt particles behind.
How to Do the Desalination Science Project
You can filter your own freshwater with this simple water purifier experiment.
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Supplies for the Desalination Experiment
- Large glass container with a wide mouth (we used this one) (affiliate)
- Small glass container that is shorter than the walls of your first container (we used a small storage container) (affiliate)
- Kitchen plastic wrap (affiliate)
- Rock or other heavy object (but not heavy enough to break through the plastic film)
- Salt (affiliate)
What You Need for a Science Fair
You’ll want to have these supplies on hand before doing your science fair project. Shop the included Amazon storefronts to make things easier and don’t forget to download the free science fair planning checklist before getting started!
Science Fair Project Planning
When you’re planning your project, you want to keep everything organized. Click the image below to get my free science fair project checklist so you can start organizing your project from the start.
You may also want to check out this list of science fair project research supplies.
Supplies for a Science Fair Project
There are so many supplies for science fair projects that are individual to each project, but if you want a general list of possible supplies and inspiration for your project, check out my selection of science fair experiment supplies on Amazon.
Supplies for a Science Fair Presentation
Your science fair presentation is important! It should look presentable and eye-catching. Check out this list of my favorite science fair presentation supplies.
Desalination Science Project Directions
Make saltwater by adding salt to two cups of water on the stove. To make the salt dissolve faster, we boiled our water. Mix the salt until it was completely dissolved into the water.
Next, fill your large bowl with the saltwater. Place the smaller container in the center of the bowl. Make sure you don’t splash any saltwater into the center bowl or your water will not taste fresh.
The center container should also sit on the bottom of the container and not move around. We had to pour out some of our saltwater until the water level was low enough to stabilize the center container.
Cover the top of the large bowl with plastic wrap. Place your rock on top of the plastic in the center of the small container. This will encourage the water that evaporates to drip into the center container.
Place the bowl in direct sunlight for several hours. Outside is best. We left our bowl in direct indoor sunlight for about five hours and were only able to collect about two tablespoons of water during that time.
When you can’t wait any more, remove your plastic wrap and test out your water. It should taste fresh!
In fact, our water tasted much better than our filtered water usually does. The process we used to desalinate the water is also how water distillation works, which is an effective water purifier.
Monkey was not convinced that this water science for kids activity would produce freshwater until she drank the desalinized water we made. She was surprised at how effective it was!