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Gravois Mills, MO Tap Water Quality 2026

Water quality report for Gravois Mills, MO — PFAS, lead and copper results, violation history and state inspection findings from EPA SDWIS.

A look at Gravois Mills's drinking water using EPA enforcement records: violations, lead and copper results, PFAS sampling and state inspection findings.

Main Utility: Zwanzig Mhp PWSID: MO3041171 Updated: 2026 Q2
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1 violation currently open

Lead was not detected. PFAS has never been sampled at this system.

D

Gravois Mills earns a D for water quality

Graded on violations and lead, with state inspection findings. PFAS not tested.

Lead: not detected
PFAS never sampled at this system
13 violations since 2015, 1 health-based
1 violation currently open
Gravois Mills's lead level vs. all Missouri community water systems
0 ppb5 ppb10 ppb15 ppb
Lead level: Not detected — 0% of the federal action level
✓ Lower lead than % of Missouri utilities
Population Served
51
~21 connections
Water Source
Groundwater
Drawn from wells — SDWIS source code GW
Active Violations
1
1 open of 13 since 2015

Lead & Copper Testing

Lead (Pb)
90th percentile of tap samples collected across the distribution system
0% of EPA action level
Not detected
Action level: 15 ppb
Lead was not detected at the 90th percentile — the result fell below the laboratory detection limit. That is not the same as an absence of lead in every tap, and older homes with lead service lines can still show higher readings.

Contaminant Violations (2015–Present)

ContaminantTypeMeasuredLimitPeriodStatus
Groundwater Rule TREATMENT TECHNIQUE — — 2024 Unaddressed
Groundwater Rule OTHER — — 2024 Unaddressed
Lead and Copper Rule MONITORING AND REPORTING — TT 2023 Unaddressed
Public Notice OTHER — — 2023 Resolved
Consumer Confidence Rule OTHER — — 2022 Resolved
Revised Total Coliform Rule MONITORING FAILURE — — 2022 Resolved
Consumer Confidence Rule OTHER — — 2021 Resolved
Public Notice OTHER — — 2021 Resolved
Revised Total Coliform Rule MONITORING FAILURE — — 2021 Resolved
Consumer Confidence Rule OTHER — — 2020 Resolved
Revised Total Coliform Rule MONITORING FAILURE — — 2020 Resolved
Revised Total Coliform Rule MONITORING FAILURE — — 2016 Resolved
Revised Total Coliform Rule MONITORING FAILURE — — 2016 Resolved
Understanding violation types MCL violations mean a contaminant exceeded the federal maximum limit — the most serious type.
TT (Treatment Technique) violations mean required treatment procedures weren't followed, but don't necessarily mean contamination occurred.

Violation History

1 violation remains open, out of 13 recorded since 2015 (1 health-based).

About the Main Water System

Utility Zwanzig Mhp
PWSID MO3041171
Water source Groundwater — Drawn from wells — SDWIS source code GW
Population served 51
Service connections 21
Systems serving this area 2
Regulator State primacy agency
Data through 2026 Q2 — EPA SDWIS

Frequently Asked Questions

Is Gravois Mills tap water safe to drink? ▼
No federal limit is exceeded on record. 1 violation(s) remain open.
Does Gravois Mills water have PFAS? ▼
This system has never been sampled for PFAS. EPA's national monitoring covered systems serving 3,300 people or more, so no results exist — which is not evidence that none is present.
Who supplies water to Gravois Mills? ▼
Zwanzig Mhp (PWSID MO3041171), one of 2 systems serving this area. Groundwater. Drawn from wells — SDWIS source code GW
When was this system last inspected? ▼
It was last inspected on 2024-06-21. Inspectors recorded 1 significant deficiency.

What Should Gravois Mills Residents Do?

1
Read your annual water report
Your supplier publishes a Consumer Confidence Report each July covering the prior year.
2
Check for a lead service line
Lead reaches tap water mainly through service lines and household plumbing. Suppliers now publish an inventory identifying lead lines.
3
Follow the open violation
This system has an unresolved violation. Contact the supplier for its corrective-action schedule.

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