Home hazard report for 59403 — Great Falls, MT
ZIP 59403 is served by City of Great Falls (as listed by the state): 5 violations since 2016, latest lead result 12 ppb, PFAS not detected. Cascade is in EPA radon zone 1.
Health-based violations since 2016: Total Haloacetic Acids (Haa5). All are listed as resolved.
Below the current 15 ppb action level but above 10 ppb, the action level under EPA's Lead and Copper Rule Improvements (compliance from 2027). Latest round: Jan 2026.
None of the tested PFAS were found above EPA’s reporting limits in 2023–2025.
Predicted average indoor radon above 4 pCi/L — EPA’s action level. Test your home.
The nearest active Superfund site is 3.2 miles away.
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Where ZIP 59403 is
blue: utility service area · scroll or pinch to zoomDrinking water: City of Great Falls
Health-based violations
| Contaminant or rule | Health-based violations since 2016 |
|---|---|
| Total Haloacetic Acids (Haa5) | 5 |
A health-based violation means a contaminant exceeded its legal limit (MCL) or a required treatment technique was not met, as reported by the state to EPA’s SDWIS. All are listed as resolved or archived; the latest began Apr 2019.
Lead
90th-percentile lead per sampling round (90% of the homes sampled were at or below this level). Black line: EPA’s 15 ppb action level; under the Lead and Copper Rule Improvements the action level becomes 10 ppb from 2027.
PFAS (“forever chemicals”)
| Compound | Highest result | Samples with detection | EPA limit |
|---|---|---|---|
| PFOA | not detected | 0 of 4 | 4 ppt MCL |
| PFBS | not detected | 0 of 4 | — |
| PFHpA | not detected | 0 of 4 | — |
| PFHxS | not detected | 0 of 4 | — |
| PFOS | not detected | 0 of 4 | 4 ppt MCL |
| PFDA | not detected | 0 of 4 | — |
| PFHxA | not detected | 0 of 4 | — |
| PFNA | not detected | 0 of 4 | — |
| PFPeA | not detected | 0 of 4 | — |
| PFBA | not detected | 0 of 4 | — |
| HFPO-DA (GenX) | not detected | 0 of 4 | — |
EPA Fifth Unregulated Contaminant Monitoring Rule (UCMR 5), samples 2023–2025; ppt = parts per trillion (ng/L). The 4.0 ppt maximum contaminant levels for PFOA and PFOS were set by EPA in 2024; water systems have until the end of the decade to comply.
Radon in Cascade
EPA radon zone 1 — highest potential. Predicted average indoor radon above 4 pCi/L — EPA’s action level. Test your home.
Radon is a colorless, odorless radioactive gas from soil and rock, and the leading cause of lung cancer among non-smokers. EPA recommends fixing a home at 4 pCi/L or above and considering it from 2 pCi/L. A short-term test kit costs about $15–30. How radon zones work →
Superfund sites nearby
| Site | Status | Distance |
|---|---|---|
| ACM Smelter and Refinery Black Eagle, Montana · EPA ID MTD093291599 | Active (final NPL) | 3.2 mi |
EPA Superfund National Priorities List (NPL): the country’s most serious known hazardous-waste sites, each with an EPA cleanup record (linked). Distance is measured from the ZIP center to the site’s reference point; being near a site does not by itself mean exposure — EPA site pages describe what was found and how it is being cleaned up.
What this is — and isn’t. These are records your water utility and state reported to the EPA, and the EPA’s radon map for your county. They describe the system and the area, not the water from your own tap or the air in your home. For that, read your utility’s annual Consumer Confidence Report and test: lead and radon tests are inexpensive.
Questions about 59403
Who supplies drinking water to ZIP 59403?
City of Great Falls (EPA ID MT0000525), a surface water (rivers, lakes) system serving about 60,000 people, listed by the state as serving this ZIP code.
Is there lead in Great Falls, MT tap water?
The utility’s latest 90th-percentile lead result (Jan 2026) was 12 ppb; EPA’s action level is 15 ppb, falling to 10 ppb from 2027. Lead mostly comes from service lines and home plumbing, so the only way to know your tap is to test it.
Does Great Falls, MT water have PFAS?
None of the tested PFAS were found above EPA’s reporting limits in 2023–2025.
Has the water system in 59403 had violations?
Health-based violations since 2016: Total Haloacetic Acids (Haa5). All are listed as resolved.
Are there Superfund sites near 59403?
The nearest active Superfund site is 3.2 miles away. Sites within 10 miles: ACM Smelter and Refinery (3.2 mi, Active (final NPL)).
Is radon a problem in Cascade?
Cascade is in EPA radon zone 1 (highest potential). Predicted average indoor radon above 4 pCi/L — EPA’s action level. Test your home.