Make a Water Reservoir

Have you ever heard of groundwater? You can find out what it is by making your own with this project. We used the bottom of a terrarium, but any clear plastic container will work well.

What You Need:

  • Large clear plastic container
  • Pebbles
  • Sand
  • Soil
  • Dead leaves or dry grass
  • Water spray bottle

What You Do:

  1. Line the bottom of your clear container with pebbles. Make sure that the pebbles you use are close to the same size. If some are large and some are small the project won’t work as well. The layer of pebbles should just cover the bottom of the container so you cannot see the plastic when you look down.
  2. Add a layer of sand on top of the pebbles. The sand layer should be about an inch thick.
  3. Put soil on top of the sand. The soil layer should be between 2-3 inches thick.
  4. Crush up some of the leaves or grass with your hands, and sprinkle it over the soil.
  5. Use the spray bottle to slowly add water to your reservoir. Spray each corner until the soil is wet through (it will turn a darker color). Watch as the water slowly spreads through the soil and sand, until it comes to the open spaces between the pebbles. Add more water at each corner if you like.

What Happened:

The way you layered pebbles, sand, and soil made it possible for water to be held underground. As you learned in the previous experiment water can evaporate quickly. When it is stored underground water stays put. A reservoir is like a big container for water. Some reservoirs are man-made and the water might be kept there by a dam. Other reservoirs are natural. Water that is contained underground is called groundwater. Groundwater can provide water for a community by using wells. Groundwater might also slowly move through the ground, until it eventually ends up in a lake or river.