Is Hays, Montana tap water safe?
3 water systems report serving Hays. Your water depends on which one serves your address. Check your bill if unsure. This list is matched from the ZIP codes in this place, so it may include nearby systems.
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Hays/White Cow Canyon WS
Serves 840 people · Groundwater · Full report →
No health-based violations in the last 5 years; No UCMR 5 PFAS results on file; Lead 90th percentile below the action level (2023).
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Mnihnapa Water System
Serves 220 people · Groundwater · Full report →
No health-based violations in the last 5 years; No UCMR 5 PFAS results on file; Lead 90th percentile below the action level (2024).
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Old Hays
Serves 80 people · Groundwater · Full report →
No health-based violations in the last 5 years; No UCMR 5 PFAS results on file; Lead 90th percentile below the action level (2025).