Hardness
Very Hard
282 PPM · 16.5 GPG
Local water dashboard
Official source aggregationA source-transparent look at local hardness, associated public water systems, EPA compliance history, and the measurements that are—and are not—available for Knox County.
At a glance
EPA quarter 2026Q2
Hardness
Very Hard
282 PPM · 16.5 GPG
Compliance screen
No active flag
0 active health-based records
Lead 90th percentile
6.0e-4 mg/L
4% of action level
Utility match
1 system
Serves 375 people system-wide
Hardness meter
Estimated local hardness
USGS hardness classification scale
282 PPM
Parts per million
282
mg/L as CaCO₃ equivalent
Grains per gallon
16.5
1 GPG ≈ 17.1 PPM
What this means at home
At 282 PPM, mineral scale can build up on fixtures and heating elements, reduce soap lather, and leave visible spotting. Hardness is primarily an aesthetic and appliance concern—not itself a tap-water safety rating.
USGS sites used
27
Nearest site
17.7 mi
Observation range
May 22, 2017–Jul 30, 2025
Estimate confidence
Moderate
Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: 11N 2W-29.8a2 (Well).USGS source documentation ↗
Regional context
These comparisons use other indexed ZIP estimates, not utility tap samples. They help show local context without replacing a household test.
Henderson median
282 PPM
About the same1 indexed ZIP readings · Range 282–282 PPM
Illinois median
285 PPM
About the same1065 indexed ZIP readings · Range 115–408 PPM
EPA benchmark screen
Available numerical results from associated SDWIS community water systems, compared with the applicable action level or federal MCL. Federal measured-value coverage is incomplete.
Lead (PB90)
6.0e-4 mg/L
Reported Dec 31, 2024
Copper (CU90)
Not available
No numerical 90th-percentile result
Numerical coverage
1 comparable result
Missing values remain blank; absence is not treated as a pass.
Measured in mg/L
Local 6.0e-4
EPA limit 0.015
100% line = listed limit
| Contaminant or rule | System | Status | Period |
|---|---|---|---|
| Public Notice | IL0950250 | Unaddressed | Oct 12, 2025 |
| Lead and Copper Rule | IL0950250 | Unaddressed | Oct 1, 2025 |
| Public Notice | IL0950250 | Unaddressed | Aug 22, 2025 |
| LEAD AND COPPER RULE REVISIONS | IL0950250 | Unaddressed | Jul 2, 2025 |
| Consumer Confidence Rule | IL0950250 | Unaddressed | Jul 1, 2025 |
| Consumer Confidence Rule | IL0950250 | Unaddressed | Jul 1, 2025 |
| TTHM | IL0950250 | Archived | Jan 1, 2025through Dec 31, 2025 |
| Total Haloacetic Acids (HAA5) | IL0950250 | Archived | Jan 1, 2025through Dec 31, 2025 |
| LEAD AND COPPER RULE REVISIONSHealth-based | IL0950250 | Resolved | Oct 17, 2024through Oct 19, 2025 |
| LEAD AND COPPER RULE REVISIONS | IL0950250 | Resolved | Oct 17, 2024through Oct 19, 2025 |
| Consumer Confidence Rule | IL0950250 | Unaddressed | Jul 1, 2024 |
| TTHM | IL0950250 | Archived | Jan 1, 2024through Dec 31, 2024 |
| Consumer Confidence Rule | IL0950250 | Unaddressed | Jul 1, 2023 |
| Lead and Copper Rule | IL0950250 | Resolved | Dec 30, 2022through Jun 25, 2023 |
| TTHM | IL0950250 | Resolved | Sep 1, 2021through Aug 31, 2022 |
| Total Haloacetic Acids (HAA5) | IL0950250 | Resolved | Sep 1, 2021through Aug 31, 2022 |
| Public Notice | IL0950250 | Unaddressed | Dec 14, 2018 |
| Public Notice | IL0950250 | Unaddressed | Dec 14, 2018 |
No reported violation does not prove that every contaminant was tested or absent; SDWIS measured values are incomplete and lag state records.
Solutions matcher
Matched to Henderson ZIP 61439 using 282 PPM nearby hardness and 1 reported measurement benchmarks.
Scale protection
282 PPM is 2× the high-hardness trigger used by this matcher.
Designed to reduce scale on fixtures, water heaters, glassware, and plumbing throughout the home.
Compare whole-house systemsAffiliate disclosure: we may earn a commission from qualifying purchases, at no added cost to you. Product matching is educational and does not replace certified water testing.
Frequently asked
EPA ECHO shows no active health-based violation for the associated systems in this reporting snapshot. This does not prove every contaminant is absent; federal records can lag and household plumbing can change tap conditions.
Nearby USGS observations produce an estimate of 282 PPM, or 16.5 grains per gallon, classified as very hard. This is not a household tap measurement.
At 282 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.