Hardness
Very Hard
490.5 PPM · 28.7 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 Clay County.
At a glance
EPA quarter 2026Q2
Hardness
Very Hard
490.5 PPM · 28.7 GPG
Compliance screen
No active flag
0 active health-based records
Lead 90th percentile
0.001 mg/L
7% of action level
Utility match
3 systems
Serves 4,780 people system-wide
Hardness meter
Estimated local hardness
USGS hardness classification scale
490.5 PPM
Parts per million
490.5
mg/L as CaCO₃ equivalent
Grains per gallon
28.7
1 GPG ≈ 17.1 PPM
What this means at home
At 490.5 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
42
Nearest site
19 mi
Observation range
Aug 9, 2016–May 20, 2026
Estimate confidence
Moderate
Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: 33N 1E 35CC (LC-6M) (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.
Wakonda median
491 PPM
About the same1 indexed ZIP readings · Range 490.5–490.5 PPM
South Dakota median
516 PPM
25 PPM lower234 indexed ZIP readings · Range 20.5–1330 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)
0.001 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 0.001
EPA limit 0.015
100% line = listed limit
| Contaminant or rule | System | Status | Period |
|---|---|---|---|
| Groundwater RuleHealth-based | SD4600349 | Resolved | Jan 14, 2022through Feb 3, 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 Wakonda ZIP 57073 using 490.5 PPM nearby hardness and 1 reported measurement benchmarks.
Scale protection
490.5 PPM is 4× 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 490.5 PPM, or 28.7 grains per gallon, classified as very hard. This is not a household tap measurement.
At 490.5 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.