Did you know if the Earth was the size of a basketball, all of its water would fit into a pingpong ball? Only 1 percent of this water is readily accessible and most of it has to be filtered in order to drink. Using a few ingredients from around the house, you can create your own water filtering system.

Materials

* Empty water bottle

* Empty transparent cup

* Cotton

* Gravel

* Pebbles

* Sand

* Dirty water

Instructions

STEP 1: Remove the bottom of the empty water bottle.

STEP 2: Place a piece of cotton into the neck of the bottle.

STEP 3: Turn the bottle upside down and rest the bottle on the top of the empty transparent cup.

STEP 4: Place about 1 inch of pebbles on top of the cotton, then 1 inch of gravel on top of the pebbles and 1 inch of sand on top of the gravel.

STEP 5: Pour the dirty water into the top of the empty water bottle allowing the water to filter through each later into the empty transparent cup at the bottom.

Explanation

As the water passed through your filtering system the impurities were held back by the different layers of materials. Although the dirt was eliminated from the water there could still be harmful bacteria in the water, making it undrinkable.

Jason Lindsey is a science outreach educator with Hooked on Science. Check out his website, www.hookedonscience.org, for webcasts and experiments that might get you hooked on science. Send him your science questions at jlindseyhookedonscience.com. More science experiments can be found at www.semissourian.com.