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Indiana Water Quality: What the Records Can—and Cannot—Tell You

A practical guide to Indiana public-water oversight, source types, annual reports, PFAS monitoring, private wells, and address-specific testing.

Reviewed by Zero Trace Water Research TeamUpdated September 13, 2026Research standardsCorrections

2025 statewide context

Indiana's water systems are numerous, local, and source-dependent.

IDEM's 2025 annual compliance report says approximately 3,947 active public water systems supplied water in Indiana. It reports that 97% of public systems use groundwater and that an average 98.45% of the population served by community systems met current health-based standards during the four quarters of 2025.

Active public systemsApproximately 3,947
Systems using groundwater97%
Community-system population meeting standards98.45% average in 2025
Annual utility reportConsumer Confidence Report

Statewide statistics summarize systems and populations; they do not establish a result for every address. Source: IDEM 2025 Annual Compliance Report.

G

Groundwater systems

Groundwater can carry naturally occurring minerals and can be influenced by well construction, nearby land use, and wellfield protection. Hardness, iron, manganese, nitrate, arsenic, and volatile-organic monitoring are separate questions.

S

Surface-water systems

Rivers, lakes, and reservoirs require treatment for particles, microorganisms, and organic matter. Finished-water monitoring, disinfectant residual, and disinfection byproducts are more useful than raw-water assumptions.

P

Purchased or mixed water

A local distributor may buy finished water from another utility, or a large system may blend multiple sources. The wholesaler's source report and the local distributor's monitoring can both matter.

PFAS monitoring

Use the final UCMR 5 dataset with the correct PWSID.

UCMR 5 required certain public water systems to monitor for 29 PFAS compounds and lithium during 2023–2025. EPA released the final dataset in August 2026. Results can be filtered by state, system name, PWSID, source-water type, contaminant, and analytical result.

  • Match the system name and PWSID to the service address.
  • Read each compound, sample point, date, unit, and minimum reporting level.
  • Do not turn a non-detect below a reporting level into proof of absolute zero.
  • Do not treat UCMR occurrence data as a substitute for every regulatory or household question.
  • Verify the exact system model and claim when considering PFAS reduction.

Open EPA UCMR 5 Data

Reviewing PFAS and drinking-water monitoring results
Public water vs. private well

Who is responsible for the data?

Public-water customer

The serving utility samples under state and federal requirements and publishes an annual Consumer Confidence Report. The report summarizes the system; premise plumbing can still create address-specific questions.

Private-well owner

The owner is responsible for testing and maintenance. A private-well plan should consider coliform bacteria, nitrate and other locally relevant parameters, plus the well's age, construction, flooding history, nearby land use, and household symptoms.

Private-well treatment guide · ZeroTrace public-water vs. well guide

Evidence first

Turn a water question into a documented plan.

Confirm the supplier or well, collect the right evidence, compare complete treatment claims, and review installation and financing before buying.

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