While the Safe Drinking Water Act mandates testing of public water supplies in the USA, private well owners are responsible for testing and treating their own water. A small percentage of well owners perform annual testing as recommended and many never test at all for common and potentially harmful groundwater contaminants. Finding effective ways to inform residents of the risks associated with their private well drinking water and promote the testing and treatment for common contaminants is a challenge faced by federal, state, and local agencies concerned with public health. Targeting residents whose wells are most at risk for having levels of regulated contaminants above the drinking water standard is a potential way to efficiently reach individuals. Results of this study show that individuals who receive specific letters that a contaminant in a neighbor's well had exceeded the maximum contaminant levels for one of five common well water contaminants (arsenic, radon, Gross Alpha, Escherichia coli, and nitrates) were more likely to test their well than were individuals who received a general letter about common contaminants in the region. Outreach that reports more localized, specific information on contaminants in well water results in an increased chance of testing when compared with more regional and generalized contaminant information.