How does water get filtered?
When we visited
different water companies, we heard a lot about water filtration.
Groundwater is naturally filtered through layers of dirt, stone, gravel,
and sand. When the water travels through these layers, it is
cleaned. This is one of the reasons that many people think that
groundwater is very clean.
Water companies filter the water in this way,
too. Water is sent through the same kind of layers before it is sent
out to the towns that buy it.
We decided to test the idea by creating our own water
filter. You can try this, too!
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Making a water filter |
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Supplies
| A clear plastic
bottle |
| 1/2 cup dirt |
| 2 cups sand |
| 2 cups gravel |
| glass of water |
| spoon |
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Step
1: Cut the bottom off of the bottle about two
inches from the bottom. This part can be dangerous, so it is a
good idea to get help from an adult for this part. Leave the
cap on it.
Step 2:
Turn the bottle upside down so that you can pour the gravel in
it. It works best if you put larger gravel in first because it
plugs up the hole that is capped. |

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Step 3: Pour the sand over
the gravel. It will fall through the gaps in the gravel.
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| Step 4: Mix the dirt in the
water. |

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Step 5: Pour the dirty water
on top of the sand in the bottle.
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Step
6: Carefully take off the bottle cap and put
the bottle spout into a tall glass or some container that can hold
your filter upright. Watch the water seep through the sand and
gravel. In the picture to the right, you
can see the layers get darker as the water flows down through them.
Click on the picture to make it bigger and easier to see.
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Step
7: Check out that water! The layers of
sand and gravel should take out the dirt in the water.
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