Water Quality Report · Updated October 07, 2026
INDIANA AMERICAN WATER - NORTHWEST
INDIANA AMERICAN WATER - NORTHWEST delivers tap water graded A (87/100) by TapWaterSafety.org. The utility serves approximately 210,510 residents in MERRILLVILLE, Indiana using surface water. The most significant water quality concerns are: Haloacetic acids (HAA9) significantly above health guideline; Total trihalomethanes (TTHMs) significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline. For questions, the utility can be reached at 317-885-2408.
Is MERRILLVILLE tap water safe to drink?
INDIANA AMERICAN WATER - NORTHWEST delivers tap water that earns a grade of A (87/100) from TapWaterSafety.org — an excellent rating reflecting minimal contamination and full compliance with health guidelines.
The utility serves 210,510 residents in MERRILLVILLE and 1 other community, drawing from surface water.
Public testing data identifies 6 contaminants in this water above EWG's health-based guidelines, including: Haloacetic acids (HAA9), Total trihalomethanes (TTHMs), Haloacetic acids (HAA5), Chromium (hexavalent), Nitrate, Nitrate and nitrite. For most residents, a properly certified home filter at the kitchen tap is the most cost-effective way to reduce exposure to whatever's in your water. See our filter recommendations below, matched specifically to this utility's contaminant profile.
EPA compliance record
Official U.S. EPA records for INDIANA AMERICAN WATER - NORTHWEST (system ID IN5245015) for the last 3 years. Checked 2026-10-07.
Source: U.S. EPA Enforcement and Compliance History Online (ECHO), from the Safe Drinking Water Information System. See EPA's full report.
Quick actions for MERRILLVILLE residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for INDIANA AMERICAN WATER - NORTHWEST.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 19.0 ppb, 316x above the EWG health guideline of 0.06 ppb.
Total trihalomethanes (TTHMs) significantly above health guideline
Moderate concernTotal trihalomethanes (TTHMs) detected at 23.7 ppb, 158x above the EWG health guideline of 0.15 ppb.
Haloacetic acids (HAA5) significantly above health guideline
Moderate concernHaloacetic acids (HAA5) detected at 11.8 ppb, 118x above the EWG health guideline of 0.1 ppb.
Contact INDIANA AMERICAN WATER - NORTHWEST
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Treatment Plant
Recommended water filters for MERRILLVILLE
Filters matched to the specific contaminants in this water supply.
Carbon filter certified for VOCs (NSF/ANSI 53)
$180-$599Activated carbon is effective for disinfection byproducts. Look for NSF/ANSI 53 VOC reduction.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
Score breakdown
This utility's overall score of 87/100 breaks down across five weighted components. Read the full methodology →
Contaminants detected — international standards comparison
Every contaminant detected, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal (the strictest US benchmark). Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Haloacetic acids (HAA9) Disinfection byproduct |
19.0 ppb | 0.06 | — | — | — | — | — | 316× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
23.7 ppb | 0.15 | 80.0 | 100 | — | — | — | 158× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
11.8 ppb | 0.1 | 60.0 | 60 | — | — | — | 118× over |
| Chromium (hexavalent) Heavy metal |
0.303 ppb | 0.02 | — | — | — | — | — | 15× over |
| Nitrate Inorganic |
0.853 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 6.1× over |
| Nitrate and nitrite Inorganic |
0.345 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 2.5× over |
| 1,4-Dioxane Semi-volatile organic compound |
0.0588 ppb | 0.35 | — | — | 50 | 1 | — | Below guideline |
| Molybdenum Other |
1.36 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.114 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.37 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Testosterone Other |
0.018 ppt | — | — | — | — | — | — | Below guideline |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines (4th ed.), California OEHHA PHGs, EWG Tap Water Database.
INDIANA AMERICAN WATER - NORTHWEST service area
This water system serves 2 communities in Lake County, Indiana. Click any city for its dedicated tap water quality page.
Find the right filter for MERRILLVILLE water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.