Hardness
Very Hard
260 PPM · 15.2 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 Cook County.
At a glance
EPA quarter 2026Q2
Hardness
Very Hard
260 PPM · 15.2 GPG
Compliance screen
No active flag
0 active health-based records
Lead 90th percentile
0.01 mg/L
66% of action level
Utility match
1 system
Serves 21,494 people system-wide
Hardness meter
Estimated local hardness
USGS hardness classification scale
260 PPM
Parts per million
260
mg/L as CaCO₃ equivalent
Grains per gallon
15.2
1 GPG ≈ 17.1 PPM
What this means at home
At 260 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
18
Nearest site
5.9 mi
Observation range
Apr 22, 2016–May 13, 2026
Estimate confidence
Moderate
Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: BIG MARSH AT SOUTH DEERING, IL (Stream).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.
Blue Island median
260 PPM
About the same1 indexed ZIP readings · Range 260–260 PPM
Illinois median
285 PPM
25 PPM lower1065 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)
0.01 mg/L
Reported Dec 31, 2025
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 0.01
EPA limit 0.015
100% line = listed limit
| Contaminant or rule | System | Status | Period |
|---|---|---|---|
| Consumer Confidence Rule | IL0310240 | Resolved | Jul 1, 2023through Jul 3, 2024 |
| Consumer Confidence Rule | IL0310240 | Resolved | Jul 1, 2022through Jul 27, 2022 |
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 Blue Island ZIP 60406 using 260 PPM nearby hardness and 1 reported measurement benchmarks.
Scale protection
260 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 260 PPM, or 15.2 grains per gallon, classified as very hard. This is not a household tap measurement.
At 260 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.