Hardness
Very Hard
525.5 PPM · 30.7 GPG
Local water dashboard
Official source aggregationWater quality in Spearfish, SD 57793
A source-transparent look at local hardness, associated public water systems, EPA compliance history, and the measurements that are—and are not—available for Lawrence County.
No active health-based violation reported
- Primary matched system
- Whitewood
- Source water
- Groundwater
- County
- Lawrence 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
0.002 mg/L
13% of action level
Utility match
5 systems
Serves 879 people system-wide
Hardness meter
How hard is the water?
Estimated local hardness
USGS hardness classification scale
525.5 PPM
Soft
0–59Moderate
60–120Hard
121–180Very hard
181+
0–59Moderate
60–120Hard
121–180Very hard
181+
Parts per million
525.5
mg/L as CaCO₃ equivalent
Grains per gallon
30.7
1 GPG ≈ 17.1 PPM
What this means at home
At 525.5 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
22
Nearest site
35.6 mi
Observation range
May 9, 2016–Nov 20, 2024
Estimate confidence
Low
Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: 002N08E14ADDD2 (MW930412) (Well).USGS source documentation ↗
Regional context
Is 57793 typical?
These comparisons use other indexed ZIP estimates, not utility tap samples. They help show local context without replacing a household test.
Spearfish median
511 PPM
15 PPM higher2 indexed ZIP readings · Range 496–525.5 PPM
South Dakota median
516 PPM
10 PPM higher234 indexed ZIP readings · Range 20.5–1330 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)
0.002 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.
Lead (90th percentile)
Measured in mg/L
Local 0.002
EPA limit 0.015
Share of EPA benchmark
100% line = listed limit
2026Q2
- All records
- 7
- Health-based
- 1
- Active health-based
- 0
| Contaminant or rule | System | Status | Period |
|---|---|---|---|
| Revised Total Coliform Rule | SD4602354 | Archived | Sep 1, 2025through Sep 30, 2025 |
| Revised Total Coliform Rule | SD4602354 | Resolved | Oct 1, 2023through Oct 31, 2023 |
| Revised Total Coliform Rule | SD4602220 | Resolved | Oct 1, 2022through Oct 31, 2022 |
| Chlorine | SD4602220 | Resolved | Oct 1, 2022through Dec 31, 2022 |
| Total Haloacetic Acids (HAA5) | SD4602220 | Resolved | Aug 1, 2022through Sep 30, 2022 |
| TTHM | SD4602220 | Resolved | Aug 1, 2022through Sep 30, 2022 |
| Stage 1 Disinfectants and Disinfection Byproducts RuleHealth-based | SD4602257 | Resolved | Aug 4, 2021through Feb 2, 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
Your personalized water action plan
Matched to Spearfish ZIP 57793 using 525.5 PPM nearby hardness and 1 reported measurement benchmarks.
Scale protection
High-Capacity Whole House Water Softener
525.5 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.
Nearby indexed reports
Compare ZIPs in Spearfish
Estimates can differ across a city because monitoring locations and associated systems differ.
Frequently asked
Water questions for Spearfish
Is tap water safe in Spearfish?+
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 525.5 PPM, or 30.7 grains per gallon, classified as very hard. This is not a household tap measurement.
Do I need a water softener?+
At 525.5 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.