Utility-reported hardness
Unavailable
Ask your provider or test your tap
Local water dashboard
Official source aggregationWater quality in Rapid City, SD 57703
Regional hardness evidence, possible serving systems, EPA compliance history, and the measurements that are—and are not—available for Pennington County.
1 active health-based record(s) across possible systems
- Largest possible serving system
- Rapid Valley Sanitary District
- Source water
- Surface water + Groundwater
- County
- Pennington County
- Profile updated
Your tap water
What does the utility report?
Match the utility name to your water bill. These results describe the utility’s water, not a test at your home. A ZIP can include several water systems.
Utility hardness unavailable in this index
Nearby river or groundwater samples cannot tell us the hardness coming out of your tap. Ask your water provider for total hardness as CaCO₃, or test it at home.
Find an official utility report →At a glance
What the current records say
EPA quarter 2026Q2
All possible systems
Review needed
1 active health-based record
Measurements by utility
Each result belongs to a specific system.
Utility match
3 systems
Serves 11,408 people system-wide
Match the name on your water bill
Your utility’s measurements and compliance records
These are possible serving systems. A record for one system does not apply to every home in this ZIP. Confirm your provider before interpreting a measurement or notice. Federal records can lag current utility notices.
EPA snapshot: 2026Q2. Historical window begins Jan 1, 2021.
Rapid Valley Sanitary District
SD4600274 · Surface water · 11,408 people served system-wide
EPA SDWIS explicitly lists this ZIP in the system's served geography.
No active health-based record in this imported snapshot
Find this utility’s official report →Measurements (1)
An action level is a regulatory trigger, not a pass/fail health boundary. A reported zero is the value in the source record and does not establish that lead is absent at your tap.
Lead (90th percentile)
EPA SDWIS Lead and Copper Rule samples
- Reported level
- 0.003 mg/L
- Action level
- 0.015 mg/L
20% of the listed benchmark
Monitoring period: Jan 1, 2024 to Dec 31, 2024
Violation history (0)
No record returned in this imported window. This is not a guarantee of tap-water safety.
Cedar Gulch 1
SD4602301 · Groundwater · 45 people served system-wide
EPA SDWIS explicitly lists this ZIP in the system's served geography.
No active health-based record in this imported snapshot
Find this utility’s official report →Measurements (1)
An action level is a regulatory trigger, not a pass/fail health boundary. A reported zero is the value in the source record and does not establish that lead is absent at your tap.
Lead (90th percentile)
EPA SDWIS Lead and Copper Rule samples
- Reported level
- 0.001 mg/L
- Action level
- 0.015 mg/L
7% of the listed benchmark
Monitoring period: Jan 1, 2025 to Dec 31, 2025
Violation history (1)
| Rule | Status | Period |
|---|---|---|
| Stage 1 Disinfectants and Disinfection Byproducts RuleHealth-based | Resolved | Feb 1, 2025 to May 22, 2025 |
Darlington Estates
SD4600403 · Groundwater · 25 people served system-wide
EPA SDWIS explicitly lists this ZIP in the system's served geography.
1 reported active health-based record(s) for this system
Find this utility’s official report →Measurements (2)
An action level is a regulatory trigger, not a pass/fail health boundary. A reported zero is the value in the source record and does not establish that lead is absent at your tap.
Combined Radium (-226 and -228)
EPA SDWIS reported health-based violation
- Reported level
- 13 PCI/L
- Maximum contaminant level
- 5 PCI/L
260% of the listed benchmark
Monitoring period: Jan 1, 2026 to Mar 31, 2026
Gross Alpha, Excl. Radon and U
EPA SDWIS reported health-based violation
- Reported level
- 25 PCI/L
- Maximum contaminant level
- 15 PCI/L
167% of the listed benchmark
Monitoring period: Jan 1, 2026 to Mar 31, 2026
Violation history (5)
| Rule | Status | Period |
|---|---|---|
| Combined Radium (-226 and -228)Health-based | Archived | Jan 1, 2026 to Mar 31, 2026 |
| Gross Alpha, Excl. Radon and UHealth-based | Archived | Jan 1, 2026 to Mar 31, 2026 |
| Stage 1 Disinfectants and Disinfection Byproducts RuleHealth-based | Unaddressed | Nov 12, 2025 |
| Combined Radium (-226 and -228)Health-based | Archived | Oct 1, 2025 to Dec 31, 2025 |
| Combined Radium (-226 and -228)Health-based | Archived | Jul 1, 2025 to Sep 30, 2025 |
Hardness meter
What does nearby environmental evidence show?
466
PPM as CaCO₃
Very Hard
PPM
466
GPG
27.3
Regional environmental evidence
USGS hardness classification scale
466 PPM
Soft
0–60Moderate
61–120Hard
121–180Very hard
181+
0–60Moderate
61–120Hard
121–180Very hard
181+
Parts per million
466
mg/L as CaCO₃ equivalent
Grains per gallon
27.3
1 GPG ≈ 17.1 PPM
How to use regional evidence
These samples describe nearby environmental water. They cannot establish whether your tap water is soft or hard. Use a utility result or a tap test for appliance settings and treatment sizing.
USGS sites used
7
Nearest site
7.1 mi
Observation range
Jul 13, 2020–Sep 3, 2024
Regional evidence confidence
High
Median of the latest source-type-aligned hardness observation at each monitoring site within 25 miles. Nearest monitoring location: BOXELDER CREEK AT 151ST AVE NR BOX ELDER, SD (Stream).USGS source documentation ↗Evidence tier: Regional environmental evidence. This value is not used as proof of the serving utility's treated-water hardness.
Regional context
Is 57703 typical?
These comparisons use other indexed ZIP estimates, not utility tap samples. They help show local context without replacing a household test.
Rapid City median
466 PPM
About the same3 indexed ZIP readings · Range 466–688 PPM
South Dakota median
688 PPM
222 PPM lower66 indexed ZIP readings · Range 8.3–1770 PPM
Evidence-first next steps
Confirm the problem before choosing treatment
This profile can help you ask the right question. It cannot select equipment for a property without a current result from the serving utility or the tap.
Confirm the serving system
ZIP boundaries and utility service areas do not perfectly match. Verify the system on a water bill before relying on system-wide records.
Read the current utility report
An active health-based record is present. Follow the utility's current notice and public-health instructions.
Find an official utility report →Test for the decision you face
Use a tap hardness test before sizing a softener. For health concerns, use a certified laboratory and the correct sampling protocol.
Convert your hardness test result →Nearby indexed reports
More local profiles in Rapid City
Estimates can differ across a city because monitoring locations and associated systems differ.
Frequently asked
Water questions for Rapid City
Is tap water safe in Rapid City?+
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.
How hard is the water?+
Utility-reported hardness is unavailable in this index. Regional samples do not establish tap-water hardness. Ask your provider or test your tap.
Do I need a water softener?+
Confirm hardness at your tap and consider actual scale or spotting before choosing treatment. Regional environmental values cannot determine whether you need a softener. A softener addresses hardness, not every contaminant.