Public water system · MO6010659
ActivePotosi Pws
At a glance
Potosi Pws (PWSID MO6010659) is an active community water system in Washington County, Missouri. It reports serving 2,527 people through 1,236 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, 7 are health-based, and the most recent began in July 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
2,527
Service connections
1,236
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Potosi Pws compare with other water systems in Washington County?
By EPA's size categories, Potosi Pws is a small system (501 to 3,300 people). Washington County has 37 active public water systems, and Potosi Pws is the largest of them by population served. Its population served is about 10 times the county average of 243 people per system, and accounts for 28% of the 8,999 people reported by systems filed under the county. Across Missouri, the 2,943 active systems average 2,049 people each. Nationally, the average active community water system reports serving 6,703 people, so Potosi Pws is about 62% 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. Missouri has 1,612 active community water systems, 55% of the state's 2,943 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 2,521 Missouri systems (86%) list groundwater as their primary source.
Who owns and regulates Potosi Pws?
EPA lists Potosi Pws as owned by a local government. The MO state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 8 of the 37 active systems in Washington County (22%) are also owned by a local government.
Does Potosi Pws have drinking water violations?
Of the 12 most recent violations in EPA's records, 7 are health-based, and the most recent began in July 2025. The violations listed here began between September 2011 and July 2025. By type: 7 contaminant level above the legal limit, 3 public notice, recordkeeping or other, 1 reporting and 1 monitoring. The contaminant or rule involved most often is Total coliform bacteria (TCR) (7 of them). EPA lists 11 as resolved and 1 as unaddressed. 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. 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 |
|---|---|---|---|---|
| 2025-07-02 | ReportingNotification, Known or Potential LSL · code 4H | Lead and Copper Rule Revisionscode 5200 | No | Unaddressed |
| 2024-04-27 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2023-03-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2015-12-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2015-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2014-11-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2013-06-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2012-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2012-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2012-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2011-11-10 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2011-09-14 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
The 12 most recent 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.
Potosi Pws: frequently asked questions
Who runs Potosi Pws?
Potosi Pws (PWSID MO6010659) is a community water system owned by a local government. It is regulated by the MO state drinking water program.
How many people does Potosi Pws serve?
Potosi Pws reports serving 2,527 people through 1,236 service connections in Washington County, Missouri.
Where does Potosi Pws 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 Potosi Pws have any drinking water violations?
Of the 12 most recent violations in EPA's records, 7 are health-based, and the most recent began in July 2025. 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 Potosi Pws' 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. Of the 12 most recent violations in EPA's records, 7 are health-based, and the most recent began in July 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the MO state drinking water program.
Where can I find Potosi Pws' water quality report?
As a community water system, Potosi Pws 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 Washington County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Kingston K 14 School Primary | Washington | 975 | Non-transient non-community | Groundwater |
| Potosi East | Washington | 900 | Community | Groundwater |
| Ymca Trout Lodge & Camp Lakewood | Washington | 800 | Transient non-community | Groundwater |
| Washington County Pwsd 1 | Washington | 503 | Community | Purchased groundwater |
| Irondale Pws | Washington | 420 | Community | Groundwater |
| Mo American Rogue Creek Utilities | Washington | 276 | 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, “Potosi Pws, PWSID MO6010659, Missouri”, https://aquacensus.com/water-systems/missouri/potosi-pws-mo6010659 (data as of October 1, 2026).