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Johnstown, WI Tap Water Quality 2026

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

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

Main Utility: Maple Plain PWSID: 055295901 Updated: 2026 Q2
✅

No federal limits exceeded on record

Lead is 2.10 ppb, 14% of the action level and no violations are open. PFAS has never been sampled at this system.

B

Johnstown earns a B for water quality

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

Lead: 2.10 ppb — 14% of the federal action level
PFAS never sampled at this system
16 violations since 2015, 0 health-based
No violations currently open
Johnstown's lead level vs. all Wisconsin community water systems
0 ppb5 ppb10 ppb15 ppb
Lead level: 2.10 ppb — 14% of the federal action level
✓ Lower lead than 50% of Wisconsin utilities
Population Served
13
~40 connections
Water Source
Groundwater
Drawn from wells — SDWIS source code GW
Active Violations
0
16 since 2015, all resolved

Lead & Copper Testing

Lead (Pb)
90th percentile of tap samples collected across the distribution system
14% of EPA action level
2.10 ppb
Action level: 15 ppb
The 90th-percentile lead result is 2.10 ppb, 14% of the 15 ppb federal action level. The action level is a treatment trigger, not a legal maximum, and it is measured across sampled taps rather than at any single home.

Contaminant Violations (2015–Present)

ContaminantTypeMeasuredLimitPeriodStatus
Consumer Confidence Rule OTHER — — 2023 Resolved
Lead and Copper Rule MONITORING AND REPORTING — TT 2018 Resolved
Revised Total Coliform Rule MONITORING FAILURE — — 2017 Resolved
Arsenic MONITORING AND REPORTING — 0.010 mg/L 2017–2019 Resolved
Barium MONITORING AND REPORTING — 2 mg/L 2017–2019 Resolved
Cadmium MONITORING AND REPORTING — 0.005 mg/L 2017–2019 Resolved
Chromium MONITORING AND REPORTING — 0.1 mg/L 2017–2019 Resolved
CYANIDE MONITORING AND REPORTING — 0.2 mg/L 2017–2019 Resolved
Fluoride MONITORING AND REPORTING — 4.0 mg/L 2017–2019 Resolved
Mercury MONITORING AND REPORTING — 0.002 mg/L 2017–2019 Resolved
Nickel MONITORING AND REPORTING — — 2017–2019 Resolved
Antimony, Total MONITORING AND REPORTING — 0.006 mg/L 2017–2019 Resolved
Beryllium, Total MONITORING AND REPORTING — 0.004 mg/L 2017–2019 Resolved
Thallium, Total MONITORING AND REPORTING — 0.002 mg/L 2017–2019 Resolved
Asbestos MONITORING AND REPORTING — 7 MFL 2017–2019 Resolved
Selenium MONITORING AND REPORTING — 0.05 mg/L 2017–2019 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

16 violations are on record since 2015, of which 0 were health-based. All have been resolved and none remain open.

About the Main Water System

Utility Maple Plain
PWSID 055295901
Water source Groundwater — Drawn from wells — SDWIS source code GW
Population served 13
Service connections 40
Systems serving this area 1
Regulator US EPA (tribal primacy)
Data through 2026 Q2 — EPA SDWIS

Frequently Asked Questions

Is Johnstown tap water safe to drink? ▼
No federal limit is exceeded on record. No violations are currently open. Lead is 2.10 ppb, 14% of the action level.
Does Johnstown 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 Johnstown? ▼
Maple Plain (PWSID 055295901). Groundwater. Drawn from wells — SDWIS source code GW
When was this system last inspected? ▼
It was last inspected on 2025-07-23. No significant deficiencies were recorded.

What Should Johnstown 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
Flush before drinking
If water has sat in pipes more than six hours, run the cold tap for two minutes before drinking or cooking.

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