Hardness
Very Hard
316 PPM · 18.5 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 Humboldt County.
At a glance
EPA quarter 2026Q2
Hardness
Very Hard
316 PPM · 18.5 GPG
Compliance screen
Review needed
1 active health-based record
Lead 90th percentile
0.006 mg/L
40% of action level
Utility match
1 system
Serves 383 people system-wide
Hardness meter
Estimated local hardness
USGS hardness classification scale
316 PPM
Parts per million
316
mg/L as CaCO₃ equivalent
Grains per gallon
18.5
1 GPG ≈ 17.1 PPM
What this means at home
At 316 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
27.4 mi
Observation range
Jul 10, 2017–Jul 30, 2024
Estimate confidence
Low
Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: 095N24W21ADAD 1996NAWQA IADRN-2 (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.
Livermore median
316 PPM
About the same1 indexed ZIP readings · Range 316–316 PPM
Iowa median
281 PPM
35 PPM higher721 indexed ZIP readings · Range 182–834 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)
0.006 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 0.006
EPA limit 0.015
100% line = listed limit
| Contaminant or rule | System | Status | Period |
|---|---|---|---|
| Lead and Copper RuleHealth-based | IA4647090 | Unaddressed | Feb 17, 2016 |
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 Livermore ZIP 50558 using 316 PPM nearby hardness and 1 reported measurement benchmarks.
Scale protection
316 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
Lead and Copper Rule 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 reports 1 active health-based violation among the associated community water systems. Review the affected utility's current notice and Consumer Confidence Report.
Nearby USGS observations produce an estimate of 316 PPM, or 18.5 grains per gallon, classified as very hard. This is not a household tap measurement.
At 316 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.