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Statewide Groundwater Monitoring Network

In 2008, the Indiana Department of Environmental Management (IDEM) Groundwater Section began collecting untreated water samples from groundwater wells statewide as part of a Groundwater 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 3000 samples have been collected from 240 public water supplies and over 1200 private residential drinking water wells. The 2016 Groundwater Monitoring Report (Currently Unavailable) 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 groundwater resources, Section 305(b) of the Environmental Protection Agency’s Clean Water Act requires IDEM to assess groundwater quality. In meeting this requirement, and the GWMN is included in the Indiana Integrated Water Monitoring and Assessment Report. Groundwater 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 groundwater quality information to local communities, citizens, research organizations, and industry.


With the GWMN, IDEM seeks to:

  1. Collect groundwater 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 groundwater 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 collected groundwater samples from private residential drinking water wells across Indiana as 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. Residents were randomly selected from a pool of applicants that met the qualifications to participate in the study, which included their location in the state and the ability to obtain a detailed well log for the well.

All wells are sampled for the National Drinking Water Contaminants, which include the following categories: volatile organic compounds, synthetic organic compounds, unregulated pesticide degradates, and inorganic compounds, and included around 200 parameters.

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


Results show constituents present across the state in areas of varying hydrogeological sensitivity. A more detailed review of preliminary findings from the GWMN can be found in the 2016 Groundwater Monitoring Network Report.

2016 Groundwater Monitoring Network Report:

Annual Sample Results (Section Centroid Locations Only):

Well locations are Section Centroid Locations Only.

If you need more site specific data, contact the Groundwater Section in the Office of Water Quality.

Understanding and Protecting Your Drinking Water


The Understanding and Protecting Your Drinking Water provides additional information about private drinking water wells or water quality for from other water sources including public water supply (city water), purchased water, spring, cistern, and rain water. The page is geared towards citizens to help address common questions that they have regarding drinking water.

Public Water Supplies

The Wellhead Protection Program or Source Water Assessment Program pages provide more information about how community public water supplies can protect our water resources.


If you have any additional questions, contact the Groundwater Section in the Office of Water Quality.

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