Big Arm, MT Tap Water Quality 2026

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

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

Main Utility: Big Arm Water System PWSID: 083090309 Updated: 2026 Q2

✅

No federal limits exceeded on record

Lead is 1.00 ppb, 7% of the action level and no violations are open. PFAS has never been sampled at this system.

Big Arm earns a B for water quality

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

Lead: 1.00 ppb — 7% of the federal action level

PFAS never sampled at this system

7 violations since 2015, 1 health-based

No violations currently open

Big Arm's lead level vs. all Montana community water systems

0 ppb5 ppb10 ppb15 ppb

Lead level: 1.00 ppb — 7% of the federal action level

✓ Lower lead than 99% of Montana utilities

Population Served

208

~23 connections

Water Source

Groundwater

Drawn from wells — SDWIS source code GW

Active Violations

7 since 2015, all resolved

Lead & Copper Testing

Lead (Pb)

90th percentile of tap samples collected across the distribution system

7% of EPA action level

1.00 ppb

Action level: 15 ppb

The 90th-percentile lead result is 1.00 ppb, 7% 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)

Contaminant	Type	Measured	Limit	Period	Status
Lead and Copper Rule	MONITORING AND REPORTING	—	TT	2023	Resolved
Groundwater Rule	TREATMENT TECHNIQUE	—	—	2017	Resolved
Gross Alpha, Excl. Radon and U	MONITORING AND REPORTING	—	15 pCi/L	2017	Resolved
Combined Uranium	MONITORING AND REPORTING	—	30 ug/L	2017	Resolved
Combined Radium (-226 and -228)	MONITORING AND REPORTING	—	5 pCi/L	2017	Resolved
Radium-226	MONITORING AND REPORTING	—	—	2017	Resolved
Radium-228	MONITORING AND REPORTING	—	—	2017	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

7 violations are on record since 2015, of which 1 were health-based. All have been resolved and none remain open.

About the Main Water System

Utility Big Arm Water System

PWSID 083090309

Water source Groundwater — Drawn from wells — SDWIS source code GW

Population served 208

Service connections 23

Systems serving this area 1

Regulator US EPA (tribal primacy)

Data through 2026 Q2 — EPA SDWIS

Frequently Asked Questions

Is Big Arm tap water safe to drink? ▼

No federal limit is exceeded on record. No violations are currently open. Lead is 1.00 ppb, 7% of the action level.

Does Big Arm 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 Big Arm? ▼

Big Arm Water System (PWSID 083090309). Groundwater. Drawn from wells — SDWIS source code GW

When was this system last inspected? ▼

It was last inspected on 2025-10-06. No significant deficiencies were recorded.

What Should Big Arm Residents Do?

Read your annual water report

Your supplier publishes a Consumer Confidence Report each July covering the prior year.

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.

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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