You can demonstrate the process of water infiltrating down through soil layers by creating a “spring in a bottle”. Water moves through diverse soil types in different ways but always with gravity, this takes place either on the surface or down-gradients under ground. If water cannot move downward any further it will flow along the impervious layer until it reaches a permeable layer.
To show this in action you can cut a two liter soda bottle four inches from the bottom and invert the top (turn it upside down) into the bottom (see photograph). Include a small hole poked into the side towards the bottom of your layers to create the spring. Place inside the inverted top different layers of sand, soil, clay and gravel. You can also add grass, charcoal or other mediums that may be available to increase layers of runoff, filtration or absorption depending on the specifics of your lesson. Add clean or dirty water to demonstrate the “spring in a bottle” or dirty “polluted” water to demonstrate the filtration.
This lesson can also be used to demonstrate water filtration in an outdoor scenario. While it won’t remove bacteria it will clarify the water to make ready for secondary forms of chemical treatment. (See my full article in Issue 20 of Self Reliance Illustrated to learn more).
Which layers were most permeable? most impermeable?
How well did the layers filter the water?
For more water related lessons check out the
Nature Into Action 