Can you build a filter to make clean water for bathing?
Problem
Your family is camping in a very remote area to get a better view of the
night sky. After a long day of hiking, you’d like to wash up, but you only
have enough water for drinking. There’s no store to purchase water from
or other campers nearby. You remember learning about water filtration
in science class and decide to try to filter water from the nearby stream.
Luckily, you have some supplies in your family’s backpacks to work with.
Your Mission
Using the materials provided, you must build a water trap and filter to
make the water clean enough for washing up.
Instructions
Cut the top of the water bottle off to create a funnel for your
water filter.
Remove the cap and place one or two coffee filters (depending on
thickness) around the smaller end of your funnel, then secure them
in place with rubber bands.
Turn your funnel upside down, and fit it into the bottom of the bottle
so water poured into the funnel will be caught in the bottle base.
Add some of the provided materials to the coffee filter. Think about
what will work best to catch debris.
Create some “dirty water.” A 1:2 mix of soil to water makes good
test material.
Pour some dirty water through each filter. Compare the clarity of
the resulting liquid to determine which filter was the most successful.
Hint
The finer a mesh you run your water through, the more dirt it will
filter out. Try building something that lets the water flow through many
different densities of material.
How to Test
Instruct your students to create a water filter.
Create some “dirty water.” A 1:2 mix of soil to water makes
good test material.
Pour two cups of dirty water through each filter.
Compare the clarity of the resulting liquid to determine
which filter was the most successful.
Example Solution
Cut the top off of your 2 liter bottle where the side starts
to slope up towards the opening.
Remove the cap and secure two coffee filters over the
opening using rubber bands.
Turn your funnel upside down, and fit it into the bottom of
the bottle so water poured into the funnel will be caught in
the bottle base.
Add a cotton ball to the bottom of the funnel. Be careful
not to push too hard as this will cause the coffee filters to
come off.
Pack some activated charcoal on top of the cotton ball.
Add some sand to help keep the charcoal from getting
unpacked and loose when water is poured in.
Student Hint
The finer the mesh you run your water through, the more
dirt it will filter out. Try building something that lets the water
flow through many different densities of material.
