Depending on the location, aquifers containing ground water can range from a few feet below the surface to several hundred feet underground. Aquifer recharge areas are locations where rainwater and other precipitation seeps into the earth's surface to enter an aquifer. Contrary to popular belief, aquifers are not flowing underground streams or lakes. Ground water moves at an irregular pace, seeping from more porous soils, from shallow to deeper areas and from places where it enters the Earth's surface to where it is discharged or withdrawn. A system of more than 100 aquifers is scattered throughout New Jersey, covering 7500 square miles.
Ground water is the primary drinking water source for half of the state's population.
Most of this water is obtained from individual domestic wells or public water supplies which tap into aquifers. Potential pollutants and other impurities can enter in different parts of the water cycle. As water returns to the Earth through the atmosphere in the form of precipitation, various impurities in the air are intercepted. When it reaches the ground, water contains both man-made and natural impurities such as carbon dioxide, dust and pollen. As water runs its course on the land, it continues to collect or dissolve oxygen, nutrients, minerals, nitrates, phosphates, carbon dioxide, and other materials, most of which are necessary for plant and animal life.