Filtering water

The Senior Science Club investigated ways to filter dirty water to make it clean.  First we cut a coke bottle in the middle and upturned the top pouring part to make a housing.  Then we placed a paper coffee filter, stones, course sand and lastly softer iron sand in layers.  When we poured muddy water through, we found the water was much cleaner as the dirt was filtered out of the water.  By the time we made filtered the water three times, it looked clear, but we still didn't drink it!