Question:
I am making a school project and I want to show purification of water how do I show it?

it has to be a working project and the water is from the feild

Answer: slow gravity filtration is the best and most efficient system in the world. But it is slow.

Take one Plexy galss tube. Attach a fine screen at the bottom. Fill with 5" of small rock(bottom), 4" of pea gravel(middle), 4" of sand(top)

Approximatly 1~2 gpm pr square foot of surface