The Wonderful World of Groundwater
Many years ago children out playing could simply pump a lever and like magic crisp, clean and very cold water would be produced. Where did this water come from? Have you figured it out? It is Groundwater. What many people do not realize is that there are aquifers filled with freshwater containing hundred times more water than all the world’s rivers and lakes combined. Groundwater is found almost everywhere and can range in depth from very shallow to miles deep. Shallow aquifers can hold water that is as recent as a few hours while the deeper aquifers where water has flowed for long distances can be several thousands of years old.
Groundwater is a very important part of the water cycle. As you know the water from the
Earth’s surface evaporates, then condenses in the atmosphere on particles to form clouds.
Once the clouds are heavy some form of precipitation falls…rain, sleet, or snow. Some of this precipitation is run-off and collects in rivers, lakes and eventually the oceans. A larger portion of the precipitation seeps through the soil due to gravity pulling the water in a downward angle toward the center of the Earth. This water continues downward until it reaches the saturated zone.
Let’s look at this process with a little more detail. As the precipitation is being pulled by gravity it is passing through many different materials. Remember how you learned that the Earth’s layers of sedimentary rock are laid down in horizontal layers with some layers being more porous than others. This (law of superposition) plays a large role in how the water from the surface is stored as groundwater. The Earth’s bedrock consists of sandstone, limestone, granite, silt, rocks and much more. The bedrock can have spaces where groundwater can be stored and fractures or cracks in the rock where groundwater can also be stored. Groundwater can also be stored within materials like gravel and sand due to the porous nature. Obviously this water does not make it to the center of the Earth.
While there are many permeable areas under the surface, there are areas impermeable with very dense materials that will not allow water to move past vertically. For example

granite and clay are very dense. These layers are usually underneath the more porous rock layers and will act as a shield to stop the vertical movement of the groundwater. The saturation zone is where the groundwater is stored and is just below the water table.
Now that you know what groundwater is and how it collects and is stored what about how it is used. Close to 99% of groundwater used is from freshwater aquifers. We use groundwater for just about all of our daily functions and then some. Groundwater is used in abundance for irrigating crops to produce the food you eat every day. Groundwater is also used by local city and county water departments. This water is delivered to homes, just like the one you live in to drink, bathe, cook, wash clothes and all the other things we use water for on a daily basis. Groundwater pumped from the aquifers is also used for firefighting, industry, businesses, public building and we cannot leave out the Community pools that keep you cool and entertained in the summer months. The majority of groundwater is for direct human usage but the mining industry uses more groundwater than surface water to mine for coal. This is indirectly linked to humans since we rely heavily on coal for electricity.

A few last points of interest about groundwater… Since Earth’s materials become denser with depth, groundwater is found close the surface. Close is defined as within a few miles of the Earth’s surface. The amount of groundwater that is stored in aquifers depends on the permeability of the soil and other materials the water is seeping through. Permeability will allow the water to move rapidly for the drilling of wells. Wells allow the water from aquifers to be pumped through pipes into homes and businesses.