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Community Water System · PWS MO2010515

Mercer PWS

Mercer, Missouri 64661-0000 - drinking water served from groundwater sources to 318 people, tracked in EPA SDWIS and UCMR5.

318
People served
118
EPA violations
50
Health-based
Untested
UCMR5 result

The verdict

EPA records 118 drinking-water violations at Mercer PWS, 42% of them health-based - above the Missouri per-system average.

118
Total EPA violations on record
42%
Health-based (MCL / treatment failure)
318
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Mercer PWS

Mercer PWS is a local-owned community water system that delivers drinking water to 318 residents in Mercer, Missouri (Mercer County) through 186 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 118 total violations for this system , of which 50 (42%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 64 monitoring and reporting violations are on file. The most recent violation on record dates to 2025.

The most frequently cited contaminant at this system is Coliform (TCR), recorded in 50 violations (MR). This system has not yet been sampled under EPA's UCMR5 PFAS monitoring program, so no PFAS detection data is available here.

Across Missouri, EPA tracks 2,823 public water systems serving 5,855,885 people, with 201,695 cumulative violations and 54,821 health-based violations on record. About 95% of systems in the state carry at least one violation, and state-wide the average per system is 71.4 violations. Statewide, 71 of 230 UCMR5-tested systems have reported PFAS detections (30.9%).

Mercer PWS's 118 violations sit above the Missouri average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

Population Served
318
Total Violations
118
Health-Based Violations
50
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Local
Connections
186
County
Mercer
School/Daycare
No
MCL Violations
39
Monitoring Violations
64
Treatment Tech Violations
11

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Coliform (TCR) MR 50 2012
TTHM MCL 36 2025
Surface Water Treatment Rule TT 11 1993
Total Haloacetic Acids (HAA5) MR 4 2023
TTHM MR 4 2023
Revised Total Coliform Rule MON 4 2020
Coliform (TCR) MCL 3 1998
Lead and Copper Rule MR 2 2011
Public Notice Other 2 2021

Verify This Water System

The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Mercer PWS.

Federal Source of Truth

EPA SDWIS, Federal Reports

EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:

View PWS ID MO2010515 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

Missouri Drinking Water Authority

Missouri DNR, Public Drinking Water Branch is the primacy agency that licenses and inspects Mercer PWS under EPA-delegated authority.

Open MO regulator portal

Source: Missouri DNR, Public Drinking Water Branch

Violation Timeline

Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.

Year (latest) Contaminant Category Count EPA Record
2025 TTHM MCL 36 SDWIS / MO2010515 / 2950
2023 Total Haloacetic Acids (HAA5) MR 4 SDWIS / MO2010515 / 2456
2023 TTHM MR 4 SDWIS / MO2010515 / 2950
2021 Public Notice Other 2 SDWIS / MO2010515 / 7500
2020 Revised Total Coliform Rule MON 4 SDWIS / MO2010515 / 8000
2012 Coliform (TCR) MR 50 SDWIS / MO2010515 / 3100
2011 Lead and Copper Rule MR 2 SDWIS / MO2010515 / 5000
1998 Coliform (TCR) MCL 3 SDWIS / MO2010515 / 3100
1993 Surface Water Treatment Rule TT 11 SDWIS / MO2010515 / 0200

How Mercer PWS Compares

Cross-reference this system's record against state averages and the federal MCL framework for context.

Metric Mercer PWS Missouri avg Federal benchmark
Total violations 118 71.4 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 50 19.4 Indicates a contaminant exceeded a federal MCL
PFAS detection None 30.9% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 318 2,074 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 2,823 regulated public water systems in Missouri.

Federal MCL reference, Safe Drinking Water Act thresholds ▼
Contaminant Federal MCL / Action Level Note
Lead 0 mg/L (Action Level: 0.015 mg/L) Lead and Copper Rule treatment technique
Arsenic 0.010 mg/L (10 ppb) Health-based MCL since 2006
Total Coliform Treatment technique (RTCR) Indicator organism, monitoring trigger
PFOA / PFOS (PFAS) 4.0 ppt each (final 2024 rule) Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026)
Nitrate (as N) 10 mg/L Acute health risk for infants

Frequently Asked Questions

Is Mercer PWS water safe to drink? ▼
Mercer PWS (PWS ID: MO2010515) has 118 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 318 people using Groundwater sources.
How many people does Mercer PWS serve? ▼
Mercer PWS serves 318 people in Mercer, Missouri. It is a Local-owned system using Groundwater water sources with 186 service connections.
What type of violations does Mercer PWS have? ▼
Mercer PWS has 118 total violations: 50 health-based violations (MCL exceedances or treatment failures), 64 monitoring/reporting violations, and 11 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Mercer PWS water? ▼
No PFAS testing data is available for Mercer PWS under the EPA's UCMR5 monitoring program.
What water source does Mercer PWS use? ▼
Mercer PWS uses Groundwater as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.
Where does this data come from? ▼
All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. This data is provided for informational purposes only.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.