There are two sources of drinking water: ground water and surface water. Ground water is water that has infiltrated into the ground and is stored in the soil and rock below the surface. Ground water is obtained by pumping water from the ground out of a well. Public water system wells in New Jersey range from a depth of fifteen feet to one thousand nine hundred and eighty four feet (in 2002).

The quality of drinking water from a ground water source, may be impacted from a variety of activities. These activities include cemeteries, recreational activities (for example golf courses), known contaminated sites, and underground storage tanks.

Surface water, on the other hand, is water stored in streams, rivers, lakes, and reservoirs. Precipitation that does not infiltrate into the ground or evaporate into the atmosphere runs off into the surrounding bodies of water.

Activities that may impact the quality of drinking water from a surface water source include landfills, disposal and storage sites, industrial sites, composting sites, and other landuse activities such as agriculture.