Hardness
Very Hard
268.5 PPM · 15.7 GPG
Local water dashboard
Official source aggregationWater quality in Dupo, IL 62240
A source-transparent look at local hardness, associated public water systems, EPA compliance history, and the measurements that are—and are not—available for St. Clair County.
No active health-based violation reported
- Primary matched system
- Dupo
- Source water
- Groundwater + Surface water
- County
- St. Clair County
- Profile updated
At a glance
What the current records say
EPA quarter 2026Q2
Compliance screen
No active flag
0 active health-based records
Lead 90th percentile
0 mg/L
0% of action level
Utility match
2 systems
Serves 4,684 people system-wide
Hardness meter
How hard is the water?
Estimated local hardness
USGS hardness classification scale
268.5 PPM
Soft
0–59Moderate
60–120Hard
121–180Very hard
181+
0–59Moderate
60–120Hard
121–180Very hard
181+
Parts per million
268.5
mg/L as CaCO₃ equivalent
Grains per gallon
15.7
1 GPG ≈ 17.1 PPM
What this means at home
At 268.5 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
10
Nearest site
13.7 mi
Observation range
Jun 1, 2016–Jul 16, 2024
Estimate confidence
Moderate
Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: 3N 8W-31.1a3 (Well).USGS source documentation ↗
Regional context
Is 62240 typical?
These comparisons use other indexed ZIP estimates, not utility tap samples. They help show local context without replacing a household test.
Dupo median
269 PPM
About the same2 indexed ZIP readings · Range 268.5–268.5 PPM
Illinois median
285 PPM
16 PPM lower1065 indexed ZIP readings · Range 115–408 PPM
EPA benchmark screen
Contaminant snapshot
Available numerical results from associated SDWIS community water systems, compared with the applicable action level or federal MCL. Federal measured-value coverage is incomplete.
1 pass
Lead (PB90)
0 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.
Lead (90th percentile)
Measured in mg/L
Local 0
EPA limit 0.015
Share of EPA benchmark
100% line = listed limit
2026Q2
- All records
- 9
- Health-based
- 0
- Active health-based
- 0
| Contaminant or rule | System | Status | Period |
|---|---|---|---|
| TTHM | IL1635080 | Archived | Oct 1, 2025through Dec 31, 2025 |
| Total Haloacetic Acids (HAA5) | IL1635080 | Archived | Oct 1, 2025through Dec 31, 2025 |
| Lead and Copper Rule | IL1635080 | Unaddressed | Oct 1, 2025 |
| Consumer Confidence Rule | IL1630350 | Resolved | Jul 1, 2024through Oct 28, 2024 |
| Lead and Copper Rule | IL1635080 | Resolved | Oct 1, 2022through Feb 13, 2024 |
| Lead and Copper Rule | IL1635080 | Resolved | Apr 1, 2021through May 18, 2021 |
| Public Notice | IL1635080 | Unaddressed | Mar 12, 2021 |
| Public Notice | IL1635080 | Resolved | Feb 11, 2021through Apr 14, 2021 |
| Public Notice | IL1635080 | Resolved | Feb 11, 2021through Apr 14, 2021 |
No reported violation does not prove that every contaminant was tested or absent; SDWIS measured values are incomplete and lag state records.
Solutions matcher
Your personalized water action plan
Matched to Dupo ZIP 62240 using 268.5 PPM nearby hardness and 1 reported measurement benchmarks.
Scale protection
High-Capacity Whole House Water Softener
268.5 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.
Nearby indexed reports
Compare ZIPs in Dupo
Estimates can differ across a city because monitoring locations and associated systems differ.
Frequently asked
Water questions for Dupo
Is tap water safe in Dupo?+
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.
How hard is the water?+
Nearby USGS observations produce an estimate of 268.5 PPM, or 15.7 grains per gallon, classified as very hard. This is not a household tap measurement.
Do I need a water softener?+
At 268.5 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.