Woman holding a glass of waterWithout testing, it is impossible to know whether well water is safe to drink because many harmful contaminants cannot be seen, smelled or tasted. Private well water is not regulated by the Safe Drinking Water Act, which means the well user is responsible for testing and maintaining the water quality.

The UNC Superfund Research Program (UNC SRP) is studying contamination from toxic metals in well water across NC, including arsenic, lead, cadmium, and more. Launch the NC ENVIROSCAN mapping tool to explore environmental health impacts across the state.

What is a private well?

Private wells collect groundwater for drinking and other purposes, such as irrigation. Wells connect an above ground cap or wellhead to an aquifer, a layer of underground rock soaked with water. The well is attached to a pump that draws groundwater from the aquifer and delivers it to a house or faucet. Wells can be dug, or drilled, or “washed out.” Wells can vary in depth from only a few feet to hundreds of feet where the water is deep below ground.

What is groundwater?

Groundwater is water under the earth’s surface between rocks and soils. Groundwater begins as rain or snow melt that absorbs through plant roots, soil, and rocks. It then collects in the cracks of rocks and hollow spaces underground. Eventually, groundwater returns to the surface and flows to streams, rivers, lakes, and oceans where it can evaporate and again fall to the earth as rain or snow. This entire process can take many years.

What are potential sources of groundwater contamination?

Most private well water used for drinking comes from groundwater. All water, even water from deep underground, contains some contamination. These contaminants can enter groundwater from natural or human made sources and activities, such as: the erosion of natural mineral deposits, precipitation (rainfall or snowfall), run-off, and agricultural and industrial activities. Drinking water can be affected by activities close to the drinking water source or activities that occur many miles away.

Confused about a term on this page? Check out our frequently used terms page to learn more!

Director: Rebecca Fry, PhD
Deputy Director: Fernando Pardo-Manuel de Villena, PhD
Funding provided by NIEHS grant #P42 ES031007

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