Most people are only peripherally aware of their sump pump.  It exists in their basement as a necessary evil.  It allows their basement to exist and keeps it from being flooded in areas with high water tables.  Many people think of the water from the sump as something dirty.  They don’t realize the water in their sump is ground water.  Ground water supplies half of all Americans with drinking water. It can be found virtually everywhere on the planet at depths ranging from very shallow to very deep.

When you mention groundwater to many people, the image they see is one of vast underground rivers flowing like surface water. Underground flow in open channels rarely occurs, although we can see it in cave tours. The truth is that most groundwater occurs between grains of sand, gravel, silt, or clay (“unconsolidated sediments”) or in the fractures, bedding planes, and joints of bedrock. Imagine a jug filled with marbles. Now pour water into the jug. The water is located in the spaces between the marbles. That’s how groundwater exists in unconsolidated sediments.

Ground Water and Water Table Side View Diagram
Photo Credit: USGS

Where does it come from? When rain falls to the ground, some of it is carried off as runoff down-slope into streams, lakes and other bodies of water or into sewers. However, some of it travels downward into the ground and through the underlying sediment, the upper part of which is not completely filled with water (the “unsaturated zone”). Continuing its downward route in the unsaturated zone it moves through the interconnected openings of sand, gravel, silt, and clay or openings in rock until it reaches the “saturated zone” where it becomes groundwater.


Does it concern you that you may have little knowledge about, or control over, such an important and intricate process as your water supply? Have you started hearing things that concern you about the quality of the water supply in your area?

We often take the purity of our tap water for granted and we shouldn’t. The Natural Resources Defense Council (NRDC) created a carefully researched, documented and peer-reviewed study of the drinking water systems of 19 U.S. cities called “What’s on Tap?” in June of 2003. This study found that pollution and deteriorating, out-of-date plumbing are sometimes delivering drinking water that might pose health risks to some residents.


Many cities around the country rely on pre-World War I era water delivery systems and treatment technology. Aging pipes can break, leach contaminants into the water they carry and breed bacteria which are all potential prescriptions for illness. Furthermore, old-fashioned water treatment which was built to filter out particles in the water and kill some parasites and bacteria, generally fails to remove 21st-century contaminants like pesticides, industrial chemicals, pharmaceuticals and arsenic.

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