Hardness
Very Hard
435.5 PPM · 25.5 GPG
Local water dashboard
Official source aggregationWater quality in Summit, SD 57266
A source-transparent look at local hardness, associated public water systems, EPA compliance history, and the measurements that are—and are not—available for Grant County.
No active health-based violation reported
- Primary matched system
- Summit
- Source water
- Groundwater
- County
- Grant 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 288 people system-wide
Hardness meter
How hard is the water?
Estimated local hardness
USGS hardness classification scale
435.5 PPM
Soft
0–59Moderate
60–120Hard
121–180Very hard
181+
0–59Moderate
60–120Hard
121–180Very hard
181+
Parts per million
435.5
mg/L as CaCO₃ equivalent
Grains per gallon
25.5
1 GPG ≈ 17.1 PPM
What this means at home
At 435.5 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
6
Nearest site
35.7 mi
Observation range
May 23, 2016–May 1, 2024
Estimate confidence
Low
Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: 127N49W36BBBB R(SISSETON GW WELL RB-77-K) (Well).USGS source documentation ↗
Regional context
Is 57266 typical?
These comparisons use other indexed ZIP estimates, not utility tap samples. They help show local context without replacing a household test.
Summit median
436 PPM
About the same1 indexed ZIP readings · Range 435.5–435.5 PPM
South Dakota median
516 PPM
80 PPM lower234 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 mg/L
Reported Jun 30, 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
EPA limit 0.015
Share of EPA benchmark
100% line = listed limit
2026Q2
- All records
- 4
- Health-based
- 4
- Active health-based
- 0
| Contaminant or rule | System | Status | Period |
|---|---|---|---|
| Stage 1 Disinfectants and Disinfection Byproducts RuleHealth-based | SD4600320 | Resolved | May 14, 2025through Jul 24, 2025 |
| Stage 1 Disinfectants and Disinfection Byproducts RuleHealth-based | SD4600326 | Resolved | Nov 29, 2023through Jul 22, 2024 |
| Stage 1 Disinfectants and Disinfection Byproducts RuleHealth-based | SD4600326 | Resolved | Feb 1, 2022through Sep 1, 2022 |
| Stage 1 Disinfectants and Disinfection Byproducts RuleHealth-based | SD4600326 | Resolved | Jul 1, 2021through Sep 7, 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 Summit ZIP 57266 using 435.5 PPM nearby hardness and 1 reported measurement benchmarks.
Scale protection
High-Capacity Whole House Water Softener
435.5 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
Water questions for Summit
Is tap water safe in Summit?+
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 435.5 PPM, or 25.5 grains per gallon, classified as very hard. This is not a household tap measurement.
Do I need a water softener?+
At 435.5 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.