Clean Water Experiment for Kids


We have a camping trip planned in a few weeks. The other day we purchased some water filtration straws and things to clean the water where we are heading so that it is safe to drink. This resulted in a great discussion with my kids about clean water. This clean water experiment is a hands-on way to show children a little bit about how water can be filtered.

This water filtration experiment is also great opportunity to discuss how although we are lucky to live in a place where we have access to clean water; there are millions of people around the world that do not. Although this idea can be challenging for young kids, I truly believe that it is an important conversation to have.

After discussing how important it is to protect our water and work to keep it clean, I decided to extend the idea with this STEM clean water experiment. My kids loved trying different things to get their water as clear and clean as possible. It is also a great reminder of how fortunate we are that we can simply turn on a tap and have water that is safe to drink.

This experiment is a great activity to do after a hike or walk with your kids. You can collect a bit of water from a small pond or simply add some dirt and other materials to water from home. As long as it looks dirty then you can experiment and filter it to make it clean!

This and other clean water projects for students and kids are a great experiment to try around Earth Day or when learning about the environment.

clean water experiment

When I did this experiment with my kids at home, and in a kindergarten classroom, I simply set out all of the materials and allowed children to experiment and use what they thought might work. They used trial and error to find the best materials to clean their water.

Water Filtration Experiment Materials

clean water experiment

You don’t need a lot of materials for this experiment. Try to use things that you already have on hand. I used:

  • Clear Cups
  • Dirty Water (You can add dirt, stones, sand, oil, etc.)
  • Coffee Filters
  • Elastics
  • Sand
  • Small, Medium and Large Gravel Stones
  • Plastic Baggies
  • Nylon
  • Paper Towel
  • Free Printable Activity Card

If you have other materials on hand that you think children may use to filter their water, then you can offer the materials to them.

You can also choose to give children the activity card to explain the STEM challenge. The activity card reads:

earth day clean water activity shows a printable card that says earth day stem use the materials to create a filter to clean the water.

Clean Water Experiment Steps

I started by showing children a jug filled with dirty water. (I added dirt, oil and a bit of other debris from outside.) Then I challenged the kids to find a way to clean the water. Remind children that as clear and clean as the water may look at the end of this experiment, they cannot drink it!

I set all of the supplies out for them to choose what they wanted to build their filter with.

clean water experiment

Children tried many different things and did a lot of trial and error. A few children used only the baggies and cut a small hole in the end to filter the water. They found that this only got some of the really large pieces out of the water.

clean water experiment
clean water experiment

These children tried again by adding stones and sand to their baggie. This extra layer of filtration helped and the water did run clearer.

clean water experiment

Many children found success using the coffee filter. Securing it with an elastic on the cup, or simply holding it, and slowly pouring the water onto the filter resulted in fairly clear water.

Make sure to give children enough time to do this experiment. As my kids tested their filter, they altered it each time and tried different things. Many changed their filter by adding to it or taking parts away.

clean water experiment

Clean Water Experiment Results

Many children found that by adding many different layers they were able to get their water the clearest.

clean water experiment

A few children used most of the materials that I had made available. We put a hole in the bottom of their cup and used the cup as their filter. They started by putting a coffee filter in the bottom. In the coffee filter they added small gravel and then larger gravel stones on top.

Next, they placed several pieces of paper towel and then attached a nylon on the top. When the water was poured into this filter it ran through each of the layers and the water came out fairly clear.

clean water experiment

Many children found that by changing their paper filters (paper towel and coffee filters) they were able to run their water through a second time and get it even cleaner.

clean water experiment

One problem we ran into was that there was a bit of a dye on some of the gravel stones. Our water had a pink tint to it. To prevent this, we then rinsed all of the materials to get the color off before using them again.

clean water experiment

I was really happy to see the children getting excited each time they ran the dirty water through their filter. They were very happy to see the water run through clearer each time.

clean water experiment

Some children found that just the paper towel and coffee filter worked best. So they tried using several layers of just the towel and filter. Each time they ran their dirty water through their filter, they changed the coffee filter and paper towel. This resulted in the best filter.

clean water experiment

Many children loved being able to look at the paper filters and see the dirt and debris that were caught by the filter.

This is a great hands-on experiment for children see how difficult it is to get water clean and clear.

clean water experiment

Water Filtration Experiment Extension Ideas

An important part of this water filter experiment is also making sure that children realize that even though their water looks clean and clear, it is not safe to drink. Depending where you got your water, there are lots of tiny bits of bacteria and maybe even bugs, that we cannot see. When water is properly cleaned all of those extra things in the water, that can make us sick, are removed.

If you have a microscope, you could look at the dirty and clean water on a slide to compare. This would also be a great opportunity to show children the microscopic things in the water. Or you could compare the water you filtered with drinking water

It is interesting to note that we left some of the water over night and we noticed something in the morning. Even though the water looked clean, overnight some dirt and debris had settled to the bottom of the cup. Much of this debris found at the bottom of the cups was water that had been filtered several times.

Everyone worked really hard to clean their water. In the end, they realized how lucky they are to not have to worry about having clean water. My hope is that this experiment also creates some awareness that for many people, not having clean water, is a daily concern. It also reminds children to take care of our environment and take steps to keep our air and water clean.

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