Missoula County, Montana
19 ZIP codes · Avg score 63/100 · Grade C · Updated 2026-06-04
Missoula County's water quality grade reflects a middle-ground assessment — its 19 ZIP codes range from fully compliant to violation-flagged.
How Missoula County Compares
How Missoula County Compares
Missoula County scores 8 points above the Montana state average (55/100) and 5 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-04
ZIP Code Risk Map
Water Quality Map: Missoula County, Montana
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 10.8 (asthma 10.8%, diabetes 8.7%)
Estimated additional annual cost per homeowner: $1,061, driven primarily by flood
Infrastructure: 0.303% avg pipe failure probability, 5% of ZIPs at high risk
46.2% of homes built before 1978 (lead paint era)
Violation History (2022–2024)
→ Stable trendEPA violation counts by year across Missoula County water systems. Health-based shown in red, total in blue.
Peak year: 2023 with 2 violations. Past 5 years: 4 total (4 health-based).
Source: EPA SDWIS historical violations. Data may lag 6–12 months for the most recent year.
County Health Indicators vs National Average
Black markers indicate national averages. Source: CDC PLACES, Census ACS.
Infrastructure Overview
Sources: Census ACS (housing age), EPA SDWIS (infrastructure risk model), state bridge inspection data.
Compound Risk Breakdown
Estimated additional annual cost per homeowner: $1,061
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
61,153 housing units in Missoula County
Source: U.S. Census Bureau ACS B25034 (Year Structure Built).
Water Safety Affordability
How much it costs to fix water issues relative to home values in Missoula County
Remediation costs are relatively manageable for most homeowners in Missoula County, representing a small fraction of property value.
Remediation includes water filtration, lead abatement, radon mitigation, and flood protection where applicable. Source: Census ACS, EPA SDWIS.
Health Outcomes vs National Average
CDC PLACES data for Missoula County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water Systems with Most Violations
Top 5 systems in Missoula County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Missoula Water | 68,200 | 25 |
| 2 | El Mar Estates Msla Company Water | 1,350 | 25 |
| 3 | Westview Mobile Home Park | 947 | 24 |
| 4 | Phantom Hills Water System | 810 | 24 |
| 5 | Travois Village Mobile Park | 702 | 24 |
31 total water systems serve Missoula County.
All ZIP Codes in Missoula County
19 ZIP codes tracked in Missoula County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 59823 | Bonner | 70 | B | 0 | $466K |
| 2 | 59846 | Huson | 70 | B | 1 | $398K |
| 3 | 59801 | Missoula | 69 | C | 3 | $393K |
| 4 | 59806 | Missoula | 69 | C | 3 | — |
| 5 | 59820 | Alberton | 69 | C | 4 (1 health) | $332K |
| 6 | 59833 | Florence | 68 | C | 1 | $487K |
| 7 | 59834 | Frenchtown | 66 | C | 1 | $400K |
| 8 | 59807 | Missoula | 65 | C | 3 | — |
| 9 | 59812 | Missoula | 65 | C | 3 | — |
| 10 | 59864 | Ronan | 65 | C | 10 | $272K |
| 11 | 59868 | Seeley Lake | 65 | C | 0 | $287K |
| 12 | 59802 | Missoula | 64 | C | 3 | $420K |
| 13 | 59803 | Missoula | 64 | C | 3 | $493K |
| 14 | 59808 | Missoula | 64 | C | 3 | $420K |
| 15 | 59847 | Lolo | 64 | C | 3 | $367K |
| 16 | 59804 | Missoula | 59 | C | 3 | $507K |
| 17 | 59851 | Milltown | 55 | C | 0 | $362K |
| 18 | 59825 | Clinton | 53 | D | 0 | $328K |
| 19 | 59821 | Arlee | 40 | D | 0 | $380K |
Recommended Buyer Guides for Missoula County
Filtered against EPA monitoring data and CDC lead-exposure guidance, the guides below skip the generic catalog and connect directly to the contaminants and hazards on file here.
- Best Radon Test Kits — EPA Radon Zone 1 (highest risk) dominant in county
- Best Sump Pumps — Flood is the top compound risk factor
- Best Mold Test Kits — Flood-driven moisture and mold risk
Deep Dive Reports
Detailed analysis for Missoula County, Montana
Overview
Missoula County in Montana covers 19 ZIP codes with an average Home Safety Score of C (63/100).
14 of 19 ZIP codes have recorded EPA violations. 1 health-based violation have been documented.
← Back to Montana water quality report
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Home values: U.S. Census Bureau ACS (median estimates by ZCTA)
Updated daily.