A
85

Excellent Water Quality

Hamilton, MT 59840

Ravalli County · Population served: 7,308 · Data updated March 2026

Water Systems Serving This Area

🌊
KOHALA RANCH WATER CO.
Groundwater · Pop. 850
PWSID: HI0000151
🌊
HAMILTON CITY OF
Groundwater · Pop. 5,585
PWSID: MT0000234
🌊
BIG SKY TRAILER CT HAMILTON
Groundwater · Pop. 70
PWSID: MT0000504
🌊
BITTERROOT PINES TR CT FLORENCE
Groundwater · Pop. 45
PWSID: MT0002128
🌊
PONDEROSA MOBILE HOME PARK
Groundwater · Pop. 60
PWSID: MT0002131

Contaminants Detected

ContaminantDetected LevelEPA MCLHealth GuidelineStatus
Lead
10.0
15 ppb 1 ppb Warning

PFAS / Forever Chemicals

1 detected All below limits
CompoundLevelEPA MCLHealth GuidelineStatus
PFBS3.1 ppt2000 ppt100 pptBelow limit

Violation History (Last 5 Years)

3Total (5yr)
0Health-Based
0Major

Water Quality Summary

Understanding Your Water in Hamilton

Tap water quality in Hamilton, Montana (59840) receives an overall grade of A (Excellent) with a score of 85 out of 100, based on analysis of EPA compliance data, contaminant testing, and violation history. This is 10 points above the Montana state average of 75. The area is served by 11 water systems providing water to approximately 7,308 people, using groundwater sources. Testing has found elevated levels of Lead that warrant attention. PFAS testing detected 1 compound, all currently below EPA limits.

Your Score 85/100 A
vs State 10 pts above Montana avg (75)
vs National 10 pts above national avg (75)

What a Grade A Means

A score of 85/100 means the water supply in Hamilton, MT meets or exceeds all EPA standards with minimal issues. Contaminant levels are well within safe limits, and the water system has maintained a strong compliance record. While no water supply is guaranteed perfect at the tap due to household plumbing, this is among the best-scoring areas in the country.

Groundwater: drawn from underground aquifers via wells

Health Information

What These Contaminants Mean for You

⚠️

Lead in Your Water

Lead is a toxic metal that can leach from aging pipes and plumbing fixtures.

Health Effects

Even low levels of lead exposure can cause developmental delays in children, kidney damage, and cardiovascular effects in adults. The EPA action level is 15 ppb, but health experts recommend no safe level of lead in drinking water.

Common Sources

Lead enters water primarily through corrosion of lead service lines, lead solder, and brass fixtures — especially in homes built before 1986.

What You Can Do

If lead is detected above 1 ppb, consider using a certified lead-removal filter (NSF/ANSI 53) for drinking and cooking water. Run cold water for 30 seconds before use if water has been sitting in pipes.

Common Questions

Frequently Asked Questions

Based on EPA data, tap water in Hamilton, Montana receives a grade of A (Excellent) with a score of 85/100. This indicates the water meets federal standards and has relatively few concerns. However, individual homes may still have localized issues such as lead from old plumbing.

ZIP code 59840 is served by 11 water systems using groundwater sources, providing water to approximately 7,308 people. Groundwater is naturally filtered through rock and soil, often requiring less treatment. However, it can be vulnerable to contamination from underground sources like naturally occurring arsenic, nitrates from agriculture, or PFAS from industrial sites.

Lead was detected at 10.0 ppb in Hamilton, Montana. While this is below the EPA action level of 15 ppb, it exceeds the health guideline of 1 ppb recommended by health organizations. Consider a certified lead filter, especially if you have young children.

1 PFAS compound were detected in water serving Hamilton, Montana, but all are currently below EPA limits. While levels are within regulatory standards, some health organizations recommend minimizing any PFAS exposure. Activated carbon or reverse osmosis filters can reduce PFAS levels.

Water systems serving Hamilton, Montana have received 3 violations in the last 5 years. Violations can range from paperwork issues (monitoring & reporting) to serious health-based violations where contaminant levels exceeded safe limits. Review the violation details above for specifics.

Based on detected contaminants (lead, PFAS), residents in Hamilton, Montana should consider: Reverse osmosis (RO) system — most effective for PFAS, lead, and other contaminants. Always look for filters with NSF/ANSI certification for the specific contaminants you want to remove.

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