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June 18, 2020

A new USGS geonarrative illustrates where domestic (private) wells are located and how many people are using them, based on the results of a 2019 USGS study. A domestic well typically supplies water to single household. Nearly 40 million people in the United States rely on a domestic (private) well for their drinking-water supply.

The geonarrative displays interactive maps that allow the user to view the number of people that rely on domestic wells per square kilometer and the number and percentage of people by state using domestic wells. Users can zoom in on any particular area, although the maps are not intended to be used at the scale of a single house. Locations are estimated using roads, the assumption being that homes, and therefore wells, are located near a named road.

The new research highlighted in the geonarrative projects the population that depends on domestic wells for years after 1990 to 2010, using population data from the two most recent censuses in 2000 and 2010. The 1990 census was the last nationally consistent survey of the source of drinking water to a home; subsequent census questionnaires no longer requested this information.  The number of people using domestic-well water in the contiguous U.S. is estimated to have increased 1.5% from 1990 to 2000 from 36.70 to 37.25 million people and to have increased slightly from 2000 to 2010 to 37.29 million people. Although the number of people has grown, as a percentage of the population it has decreased, from 16.4% in 1970 to an estimated 12.2% in 2010.

Knowing the location of domestic wells and the populations they serve can aid in optimizing groundwater-quality testing to help ensure safe drinking water in private wells nationwide. For instance, knowing where a high density of private well use overlies potentially corrosive groundwater could help focus water-quality testing for lead.


Journal article citation: Johnson, T.D., Belitz, K., Lombard, M.A., 2019, Estimating domestic well locations and populations served in the contiguous U.S. for years 2000 and 2010: Science of the Total Environment, v. 687, p. 1261-1273.

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