Groundwater, water that occurs below the surface of Earth, where it occupies all or part of the void spaces in soils or geologic strata. It is also called subsurface water to distinguish it from surface water, which is found in large bodies like the oceans or lakes or which flows overland in streams.

Groundwater also can cause erosion under the surface. As water flows through the soil, acid is formed. Minerals that are carried in groundwater can also be deposited in other places. This cycle of erosion and deposition can cause underground caves to form.

Sinkholes and caves are erosional landforms formed due to the action of ground water.

Groundwater supplies drinking water for 51% of the total U.S. population and 99% of the rural population. 64% of groundwater is used for irrigation to grow crops. Groundwater is an important component in many industrial processes. Groundwater is a source of recharge for lakes, rivers, and wetlands.

Groundwater generally is treated by drilling recovery wells to pump contaminated water to the surface. Commonly used groundwater treatment approaches include air stripping, filtering with granulated activated carbon (GAC), and air sparging. Air stripping transfers volatile compounds from water to air.

Summary

1. There are four stages needed to clean groundwater: remove the pollutant source, monitor the pollutant, model the contaminant plume, and perform remediation.
2. By testing the water in many wells for a contaminant, scientists can model the contaminant plume in an aquifer.

Groundwater can sometimes be difficult to clean up due to its location. Many times the water is pumped up a well, cleaned, and then sent back down the well into the aquifer. Sometimes an additive is placed in the groundwater that either makes the contaminants less harmful or destroys them.

Contamination of ground water can result in poor drinking water quality, loss of water supply, degraded surface water systems, high cleanup costs, high costs for alternative water supplies, and/or potential health problems. The consequences of contaminated ground water or degraded surface water are often serious.

Drinking contaminated groundwater can have serious health effects. Diseases such as hepatitis and dysentery may be caused by contamination from septic tank waste. Poisoning may be caused by toxins that have leached into well water supplies. Wildlife can also be harmed by contaminated groundwater.