Public water system · MO2010515
ActiveMercer Pws
At a glance
Mercer Pws (PWSID MO2010515) is an active community water system in Mercer County, Missouri. It reports serving 318 people through 186 service connections. Its primary water source is purchased groundwater, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, 8 are health-based, and the most recent began in January 2026.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
318
Service connections
186
Primary source
GWP
Purchased groundwater
System type
CWS
Community water system
System record
How does Mercer Pws compare with other water systems in Mercer County?
By EPA's size categories, Mercer Pws is a very small system (500 people or fewer). Mercer County has 2 active public water systems, and Mercer Pws is the 2nd-largest of them by population served. Its population served is about 60% below the county average of 801 people per system, and accounts for 20% of the 1,601 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 Mercer Pws 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. Missouri has 1,612 active community water systems, 55% of the state's 2,943 active systems. Purchased groundwater means the system buys groundwater from another public water system rather than drawing its own. 177 Missouri systems (6%) list purchased groundwater as their primary source.
Who owns and regulates Mercer Pws?
EPA lists Mercer 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. 2 of the 2 active systems in Mercer County (100%) are also owned by a local government.
Does Mercer Pws have drinking water violations?
Of the 12 most recent violations in EPA's records, 8 are health-based, and the most recent began in January 2026. The violations listed here began between October 2020 and January 2026. By type: 8 contaminant level above the legal limit, 2 monitoring and reporting and 2 public notice, recordkeeping or other. The contaminant or rule involved most often is Total trihalomethanes (TTHM) (9 of them). EPA lists 8 as resolved and 4 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 |
|---|---|---|---|---|
| 2026-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2025-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2025-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2025-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2024-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 2024-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 2024-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 2023-07-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2023-07-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2021-04-08 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2021-02-01 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2020-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | 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.
Mercer Pws: frequently asked questions
Who runs Mercer Pws?
Mercer Pws (PWSID MO2010515) is a community water system owned by a local government. It is regulated by the MO state drinking water program.
How many people does Mercer Pws serve?
Mercer Pws reports serving 318 people through 186 service connections in Mercer County, Missouri.
Where does Mercer Pws get its water?
EPA SDWIS lists this system's primary water source as purchased groundwater. Purchased groundwater means the system buys groundwater from another public water system rather than drawing its own.
Does Mercer Pws have any drinking water violations?
Of the 12 most recent violations in EPA's records, 8 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 Mercer 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, 8 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 MO state drinking water program.
Where can I find Mercer Pws' water quality report?
As a community water system, Mercer 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 Mercer County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Princeton Pws | Mercer | 1,283 | 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, “Mercer Pws, PWSID MO2010515, Missouri”, https://aquacensus.com/water-systems/missouri/mercer-pws-mo2010515 (data as of October 1, 2026).