Public water system · SD4600406
ActiveRapid City
At a glance
Rapid City (PWSID SD4600406) is an active community water system in Pennington County, South Dakota. It reports serving 72,009 people through 23,171 service connections. Its primary water source is surface water, and EPA lists it as owned by a local government. EPA's records list 6 violations for this system; none is health-based, and the most recent began in October 2002.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
72,009
Service connections
23,171
Primary source
SW
Surface water
System type
CWS
Community water system
System record
How does Rapid City compare with other water systems in Pennington County?
By EPA's size categories, Rapid City is a large system (10,001 to 100,000 people). Pennington County has 150 active public water systems, and Rapid City is the largest of them by population served. Its population served is about 77 times the county average of 930 people per system, and accounts for 52% of the 139,467 people reported by systems filed under the county. Across South Dakota, the 699 active systems average 1,387 people each. Nationally, the average active community water system reports serving 6,703 people, so Rapid City is about 11 times that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. South Dakota has 510 active community water systems, 73% of the state's 699 active systems. Surface water means the system draws its water from rivers, lakes, streams or reservoirs. 24 South Dakota systems (3.4%) list surface water as their primary source.
Who owns and regulates Rapid City?
EPA lists Rapid City as owned by a local government. The SD state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 12 of the 150 active systems in Pennington County (8%) are also owned by a local government.
Does Rapid City have drinking water violations?
EPA's records list 6 violations for this system; none is health-based, and the most recent began in October 2002. The violations listed here began between July 1976 and October 2002. By type: 6 monitoring and reporting. The contaminant or rule involved most often is Gross alpha (excluding radon and uranium) (2 of them). EPA lists 3 as resolved and 3 as archived. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed. Archived means the violation was not marked resolved but is more than five years past the end of the noncompliance period, so it no longer counts toward current compliance status.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2002-10-01 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Resolved |
| 2002-10-01 | Monitoring and reportingMonitoring, Regular · code 03 | Combined Uraniumcode 4006 | No | Resolved |
| 2002-10-01 | Monitoring and reportingMonitoring, Regular · code 03 | Combined Radium (-226 and -228)code 4010 | No | Resolved |
| 1999-04-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1976-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Combined Radium (-226 and -228)code 4010 | No | Archived |
| 1976-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Archived |
All 6 violations in EPA's records, newest first.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
Rapid City: frequently asked questions
Who runs Rapid City?
Rapid City (PWSID SD4600406) is a community water system owned by a local government. It is regulated by the SD state drinking water program.
How many people does Rapid City serve?
Rapid City reports serving 72,009 people through 23,171 service connections in Pennington County, South Dakota.
Where does Rapid City get its water?
EPA SDWIS lists this system's primary water source as surface water. Surface water means the system draws its water from rivers, lakes, streams or reservoirs.
Does Rapid City have any drinking water violations?
EPA's records list 6 violations for this system; none is health-based, and the most recent began in October 2002. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is Rapid City's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. EPA's records list 6 violations for this system; none is health-based, and the most recent began in October 2002. For current results, consult the system's annual water quality report, EPA ECHO, or the SD state drinking water program.
Where can I find Rapid City's water quality report?
As a community water system, Rapid City must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in Pennington County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Box Elder | Pennington | 14,000 | Community | Groundwater |
| Rapid Valley Sanitary District | Pennington | 11,408 | Community | Surface water |
| Ellsworth Afb | Pennington | 9,100 | Community | Purchased surface water |
| Nps-Mount Rushmore National Memorial | Pennington | 4,100 | Non-transient non-community | Groundwater |
| Colonial Pine Hills Sanitary Distric | Pennington | 1,200 | Community | Groundwater |
| Chapel Lane Water Company | Pennington | 1,200 | Community | Groundwater |
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About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “Rapid City, PWSID SD4600406, South Dakota”, https://aquacensus.com/water-systems/south-dakota/rapid-city-sd4600406 (data as of October 1, 2026).