Public water system · SD4600403
ActiveDarlington Estates
At a glance
Darlington Estates (PWSID SD4600403) is an active community water system in Pennington County, South Dakota. It reports serving 25 people through 15 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. EPA's records list 5 violations for this system; all are health-based, and the most recent began in January 2026.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
25
Service connections
15
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Darlington Estates compare with other water systems in Pennington County?
By EPA's size categories, Darlington Estates is a very small system (500 people or fewer). Pennington County has 150 active public water systems. Its population served is well below the county average of 930 people per system, and accounts for less than 0.1% 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 Darlington Estates is well below 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. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 431 South Dakota systems (62%) list groundwater as their primary source.
Who owns and regulates Darlington Estates?
EPA lists Darlington Estates as privately owned. 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. 134 of the 150 active systems in Pennington County (89%) are also privately owned.
Does Darlington Estates have drinking water violations?
EPA's records list 5 violations for this system; all are health-based, and the most recent began in January 2026. The violations listed here began between July 2025 and January 2026. By type: 4 contaminant level above the legal limit and 1 required treatment not met. The contaminant or rule involved most often is Combined Radium (-226 and -228) (3 of them). EPA lists 4 as archived and 1 as unaddressed. 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. Unaddressed means the violation is not resolved or archived and is not yet covered by formal enforcement.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2026-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Archived |
| 2026-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Gross alpha (excluding radon and uranium)code 4000 | Yes | Archived |
| 2025-11-12 | Required treatment not metTreatment Technique No Certif. Operator · code 12 | Stage 1 Disinfectants and Disinfection Byproducts Rulecode 0400 | Yes | Unaddressed |
| 2025-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Archived |
| 2025-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Archived |
All 5 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.
Darlington Estates: frequently asked questions
Who runs Darlington Estates?
Darlington Estates (PWSID SD4600403) is a community water system privately owned. It is regulated by the SD state drinking water program.
How many people does Darlington Estates serve?
Darlington Estates reports serving 25 people through 15 service connections in Pennington County, South Dakota.
Where does Darlington Estates get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does Darlington Estates have any drinking water violations?
EPA's records list 5 violations for this system; all are health-based, and the most recent began in January 2026. 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 Darlington Estates' 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 5 violations for this system; all are health-based, and the most recent began in January 2026. For current results, consult the system's annual water quality report, EPA ECHO, or the SD state drinking water program.
Where can I find Darlington Estates' water quality report?
As a community water system, Darlington Estates 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 |
|---|---|---|---|---|
| Rapid City | Pennington | 72,009 | Community | Surface water |
| 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 |
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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, “Darlington Estates, PWSID SD4600403, South Dakota”, https://aquacensus.com/water-systems/south-dakota/darlington-estates-sd4600403 (data as of October 1, 2026).