Your local water, explained

Indiana water quality reports

Indiana’s 10 largest counties

Start with one of Indiana’s 10 most populous counties, ranked using the U.S. Census Bureau’s July 1, 2025 estimates. Then match the supplier on your water bill.

#1 · 992,196 residents

Marion County

Indianapolis utility results, chloramines and hard-water scale.

Browse reports → #2 · 504,612 residents

Lake County

Northwest Indiana Operations: Lake Michigan supply and plant-specific hardness.

Browse reports → #3 · 402,329 residents

Allen County

Fort Wayne City Utilities: treated river water and remaining hardness.

Browse reports → #4 · 387,036 residents

Hamilton County

Carmel’s measured hardness, treatment target and utility results.

Browse reports → #5 · 272,861 residents

St. Joseph County

South Bend groundwater, very hard water and dated monitoring notices.

Browse reports → #6 · 208,774 residents

Elkhart County

Elkhart utility sampling, PFAS results and hardness testing guidance.

Browse reports → #7 · 193,510 residents

Hendricks County

Brownsburg system results kept separate from purchased Citizens water.

Browse reports → #8 · 190,456 residents

Tippecanoe County

Lafayette hardness analysis, utility results and monitoring context.

Browse reports → #9 · 181,995 residents

Vanderburgh County

Evansville’s Ohio River supply, chloramines and water hardness.

Browse reports → #10 · 176,049 residents

Porter County

Valparaiso groundwater and Northwest Indiana’s Lake Michigan supply.

Browse reports →

These county guides summarize 10 named water systems. County population is used to prioritize guides; it does not measure how many residents use the listed utilities.

What this means for your home

These are utility measurements, not a test at your tap or a current service advisory.

We keep each utility’s results separate, show the reported sample year, and distinguish averages, maxima and tap-sampling percentiles. Hardness classifications use USGS ranges. Missing data stays unknown.

County population ranking: STATS Indiana / U.S. Census Bureau, July 1, 2025 estimates ↗USGS hardness classification ↗Filter vs. softener: what each does

Your water → your home → your system

Turn your report into a plan for your home.

Choose the system size, keep useful existing equipment, and review your filtration goals.

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