Domestic wells (aka private wells) provide drinking water supply for approximately 40 million people in the United States. Knowing the location of these wells, and the populations they serve, is important for identifying heavily used aquifers, locations susceptible to contamination, and populations potentially impacted by poor-quality groundwater.

On a national scale, domestic well locations are not well known. The 1990 census was the last nationally consistent survey of each home’s source of water, and there has been no resurvey since. Therefore, the authors developed a method for estimating the population dependent on domestic wells for years 2000 and 2010 by using census variables.

Using the 1990 census data, a relationship was found between the proportion of people using domestic wells (aka the Domestic Ratio (DR)) and the household density (HD). As household density increases, the ratio of people using domestic wells decreases, after an initial threshold is reached. Densely populated cities have a smaller percentage of people using domestic wells than in rural areas. This relationship was subsequently applied to the 2000 and 2010 census data.

This map shows the number of people using domestic wells per square kilometer for the year 2010. The map is based on the "Road-Enhanced Method" which locates domestic wells near roadways (Johnson and Belitz 2017). The assumption being that domestic wells are usually located near a home and homes are usually near a named roadway.

For more information describing this work, the article can be found here:

Johnson, T.D., Belitz, K., Lombard, M.L., 2019, Domestic well locations and populations served in the contiguous U.S. for 2000 and 2010. Science of the Total Environment 687, pp. 1261-1273. https://doi.org/10.1016/j.scitotenv.2019.06.036.

The datasets can be downloaded here:

Johnson, T.D., and Belitz, K., 2019, Domestic well locations and populations served in the contiguous U.S.: datasets for decadal years 2000 and 2010. U.S. Geological Survey data release, https://doi.org/10.5066/P9FSLU3B.