There are two main sources of water, groundwater and surface water. Ninety five per cent of those fresh water resources in U.S. come from groundwater. Build a 6-centimeter layer of gravel on the bottom of the tray to represent the aquifer. Place a loose layer of soil over the gravel. Add a few drops of food coloring to the water in the watering can and sprinkle the colored water on the soil.
Children observe what happens with precipitation.
The colored water should infiltrate the soil and begin to fill the space between the stones on the bottom of the tray. The groundwater will also move laterally to fill the lake area. Continue adding precipitation until the water table is three or four centimeters high as measured by a ruler held by the tray. Demonstrate the impact of human activity on the aquifer. Place a coffee filter over the open end of spray pump and secure with the rubber band.