Statewide Ground Water Monitoring Network

In 2008, the Indiana Department of Environmental Management (IDEM) Ground Water Section began collecting untreated water samples from ground water wells statewide as part of a Ground Water Monitoring Network (GWMN). A large percentage of Hoosiers drink residential well water that is not regulated by the Safe Drinking Water Act, and this was the impetus for starting the GWMN in Indiana. Since 2008, over 2294 samples have been collected from 240 public water supplies and over 1200 private residential drinking water wells. The 2016 Ground Water Monitoring Report provides a summary of this statewide effort characterizing Indiana’s important natural resource.

In addition to the value of knowing the drinking water quality of Indiana’s ground water resources, Section 305(b) of the Environmental Protection Agency’s Clean Water Act requires IDEM to assess ground water quality. In meeting this requirement, and the GWMN is included in the Indiana Integrated Water Monitoring and Assessment Report. Ground water monitoring is also included in the Indiana Water Quality Monitoring Strategy (fact sheet available on the IDEM Fact Sheets page). The data collected by the GWMN will assist government regulators with source water and watershed protection, and provide ground water quality information to local communities, citizens, research organizations, and industry.


With the GWMN, IDEM seeks to:

  1. Collect ground water samples from public water supply (PWS) wells and private residential wells within distinct hydrogeologic areas of the state with the overall goal to determine the quality of ground water in the state’s aquifers,
  2. Identify and expand sampling in areas with notable contamination, and
  3. Practice continual improvement adjusting the GWMN as necessary to best fit resources (monetary/field support) and data gap needs.


IDEM samples private residential wells in all 92 counties in Indiana that eventually becomes part of the GWMN. Testing is conducted free of charge, and copies of the analytical results are provided to the resident at the end of the study season. If you are interested in participating in this study, the Statewide Ground Water Monitoring Network Survey page provides additional information, eligibility requirements, and a link to the application.

Sampling occurs annually, usually during the summer, spring or fall. IDEM samples for over 400 parameters. All wells are sampled for the National Drinking Water Contaminants, which include the following categories: volatile organic compounds, synthetic organic compounds, and inorganic compounds.

In addition, IDEM also samples for pesticide breakdown products, which are not regulated.


Results, show constituents, such as nitrates [JPG] [PDF] and arsenic [JPG] [PDF], present across the state in areas of varying hydrogeological sensitivity. Continued annual sampling will give IDEM an opportunity to explore trend analysis, seasonal variations, and the relationship between sensitivity and hydrogeological setting. For more detailed review, our annual report summaries will be posted soon.

Annual Sample Results (Section Centroid Locations Only):

If you need more site specific data, please IDEM at (317) 232-8488, or via email at

2016 Ground Water Monitoring Network Report:


Additional Information: