This project was created to give students a look into how a water filter works, and why it is important for clean water to be available for everyone. This project is intended to be used in a middle school classroom and can be done by students in grades 6-8. It is recommended to be used by older students as younger students may have issues using cutting tools independently. If you feel that your students may not be ready to use cutting tools like a box cutter or X-acto knife, scissors can be used instead.

This project can be done individually or by students in groups of 2 or 3. Students are recommended to hypothesize how the water will be filtered before conducting the experiment and to discuss amongst themselves why water filtration is important after completing the assignment. This project can be done in conjunction with a presentation on the water cycle or on how clean water isn't available in all areas.

This project was created in alignment with the 2020 Standards for Technological Literacy, and the corresponding standards, practices, and contexts are listed below.

Learning Objective:

Students will use plastic water bottles and filtration materials to create a rudimentary water filter; students will gain insight into how water is filtered and will ask questions about why access to clean, potable water is important. The end product is a rudimentary water filter that will clean water using 3 different filtration mediums.

Standard:

Impacts of Technology- Lack of access to clean water has negatively impacted developed and developing countries. The introduction of new water filtration technology has made water more accessible and safer to use. Students will learn how to create a rudimentary water filter that will clean water without the use of chemicals or heat. Students will learn the importance of having clean accessible water.

Practice:

Attention to Ethics- Students will learn how denying humans access to clean and drinkable water is an ethical issue. By creating a rudimentary water filtration system, students will learn that there are easy solutions to safely filter water. Students should research clean water initiatives and should research how outreach groups are bringing filtration to needy communities.

Context:

Medical and Health-Related Technologies- By putting together a rudimentary water filtration system, students will see impurities removed from the water. This will demonstrate visually what unclean water looks like, and how health issues can stem from not having potable water.

Supplies

For this project the students will need:

3 disposable water bottles (preferably sturdy plastic)
A box cutter or X-acto knife
Aquarium gravel
Aquarium sand
Cotton Balls
Coffee filters
Water

Step 1: Prepping Your Bottles

After gathering supplies, students should use their cutting tools to remove the outer wrapper from the bottle.

Be sure to not puncture the bottle during this step.

Step 2: Cutting Your Bottles

Please make sure that your students are briefed on sharp object safety before they attempt this step. Be prepared to offer assistance with cutting if needed.

Students should use their cutting tools to cut their bottles in half. Some bottles may have a depression at the halfway point that will make cutting easier. If your bottles do not have a depression, don't worry about being exact. Guesstimating the halfway point of the bottle is completely fine.

You should have 3 bottle tops and 3 bottoms by the end of this step

Step 3: Filling Your Bottles

Take your 3 bottle tops and place a coffee filter in each.

Then, fill each filter with gravel, sand, and cotton balls respectively. You will want to leave enough room to be able to stack your bottle tops one on top of the other.

Be sure to check that you have left enough space as you pour the filtration medium in, as it is difficult to put back in the bag after it has been poured.

Step 4: Prep Your Water

Using one of the bottle bottoms, mix sand and water together to create contaminated water.

There are no specific measurements for this part, but it is recommended to use lots of water and less sand than you think you'll need.

Be sure to agitate the mixture by swirling the container or mixing with a finger to make sure the sand and water are fully incorporated.

Step 5: Construct Your Filter

Stack your bottle tops one on top of the other and place them on top of one of the bottle bottoms. The order should be:

Bottom: empty bottle bottom
1st layer: cotton balls
2nd layer: sand
Top layer: gravel

Keep in mind that after construction your filter will be top-heavy. It is recommended that your students keep one hand on the filter at all times after this step.

Step 6: Use Your Filter

Students should once again stir/swirl their contaminated water to loosen up any sediment that has settled. Then students should pour the water into the filter.

It may take a few seconds for the water to filter through, but soon your students will see the clean water pooling at the bottom of the filter.

After completing this experiment, students should discuss among themselves why they think it is important to have filtered water. Optionally, students should research outreach programs that work to bring clean water and easy filtration devices to places that need it.