Your bones are 25% water.
Your brain and muscles are 75% water.
Your lungs are nearly 90% water.
Learning Topic: What is Ground Water

What is Ground Water?

Groundwater is the water that is found beneath the surface of the earth.  It originates as either rainfall or snowmelt that seeps in through the soil and recharges the groundwater resource.  It is stored in the spaces between soil particles or in the cracks in the bedrock. 

The saturated zone is that area below the earth’s surface where the spaces between the soil particles or the cracks in the bedrock are saturated with water.  The water table marks the boundary between the saturated zone and the unsaturated zone.  In the unsaturated zone, the spaces between the soil particles and the cracks in the bedrock may contain water, but, may also contain air, sediments, plant roots and other living creatures.

Wells are placed into the saturated zone below the water table to allow us to access the groundwater for drinking water purposes.

The water table fluctuates throughout the season.  During a typical year, the water table is closest to the earth’s surface during the late winter or early spring and tends to drop deeper below the earth’s surface in late summer and early fall.  The reasons for this is that we tend to get less rain in late summer, the plants and trees are using a large amount of water, and people typically use more water during this time of year.

Groundwater is stored in what are commonly called aquifers.  An aquifer is a geologic formation that is capable of both storing groundwater and supplying that water to wells for our use.  In New England, we rely on two types of aquifers for drinking water purposes. 

Sand and gravel aquifers are layers of sorted sands and gravel deposits.  These aquifers are very productive in that they can store a lot of water and readily supply this water to water supply wells.  Bedrock aquifers store the groundwater in cracks, or fractures, in the bedrock.  The productivity of a bedrock aquifer is dependent upon both the size of the fractures and their interconnectedness.

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