Hardness
Very Hard
404 PPM · 23.6 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 Sanilac County.
At a glance
EPA quarter 2026Q2
Hardness
Very Hard
404 PPM · 23.6 GPG
Compliance screen
No active flag
0 active health-based records
Lead 90th percentile
0.001 mg/L
7% of action level
Utility match
1 system
Serves 2,447 people system-wide
Hardness meter
Estimated local hardness
USGS hardness classification scale
404 PPM
Parts per million
404
mg/L as CaCO₃ equivalent
Grains per gallon
23.6
1 GPG ≈ 17.1 PPM
What this means at home
At 404 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
49
Nearest site
10 mi
Observation range
Aug 3, 2016–Sep 11, 2023
Estimate confidence
Moderate
Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: SUS147-25 (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.
Croswell median
404 PPM
About the same1 indexed ZIP readings · Range 404–404 PPM
Michigan median
283 PPM
121 PPM higher504 indexed ZIP readings · Range 41.3–459.5 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, 2023
Copper (CU90)
2.4 mg/L
Reported Dec 31, 1993
Numerical coverage
2 comparable results
Missing values remain blank; absence is not treated as a pass.
Measured in mg/L
Local 0.001
EPA limit 0.015
Measured in mg/L
Local 2.4
EPA limit 1.3
100% line = listed limit
| Contaminant or rule | System | Status | Period |
|---|---|---|---|
| Nitrate | MI0001690 | Resolved | Jan 1, 2023through Sep 30, 2023 |
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 Croswell ZIP 48422 using 404 PPM nearby hardness and 2 reported measurement benchmarks.
Scale protection
404 PPM is 3× 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 systemsDrinking water protection
Copper (90th percentile) has a measured benchmark flag or active health-based SDWIS record in this profile.
A certified multi-stage RO system targets a broader range of dissolved contaminants at the kitchen tap.
Explore under-sink filtrationAffiliate 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 404 PPM, or 23.6 grains per gallon, classified as very hard. This is not a household tap measurement.
At 404 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.