Big Sky County Water and Sewer District 363
EPA ID: MT0002385 · 4,132 people served · 2 ZIP codes
Big Sky County Water and Sewer District 363 recorded 1 EPA violation over the past five years, all of which have since been resolved — the utility is currently in compliance serving 4,132 residents.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for Big Sky County Water and Sewer District 363 Source: EPA SDWIS service area boundaries.
Service area boundary — Grade B
Service Area Demographics
The Big Sky County Water and Sewer District 363 serves a community with a median household income of $110,623 and an estimated 4,234 residents across its service area.
💧 Where Does Your Water Come From?
Big Sky County Water and Sewer District 363's water is pumped from underground aquifers. Groundwater is naturally filtered through rock and soil, but it can be vulnerable to PFAS contamination, nitrates from agriculture, and industrial chemicals that seep into the water table.
About 1% of homes in Gallatin County, Montana rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Wastewater Proximity Note: This service area ranks in the 60th percentile nationally for proximity to wastewater discharge points.
Superfund Proximity Note: This service area ranks in the 70th percentile nationally for proximity to Superfund (NPL) sites. Groundwater sources near contaminated sites may face elevated risk from industrial chemicals.
Infrastructure Risk
Detected Contaminants
How Big Sky County Water and Sewer District 363 compares to EPA limits
What This Means For You
Arsenic at 1 mg/L exceeds the EPA maximum of 0.01 mg/L.
Stage 1 DBP Rule at 1 mg/L exceeds the EPA maximum of mg/L.
PFAS Detected in Service Area
PFAS ("forever chemicals") have been detected in water serving this system's area. 1 detection recorded.
Comparable Water Systems
Similar-sized systems in Montana
Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
Big Sky County Water and Sewer District 363 (EPA ID: MT0002385) is a community water system in Montana that serves approximately 4,132 people from groundwater sources.
This system provides water to 2 ZIP codes across 2 communities.
Average Home Safety Score: B (70/100)
Based on water quality violations, lead levels, and radon risk across all ZIP codes served by this system.
Violation History
Recent Violations
| Date | Contaminant | Type | Status |
|---|---|---|---|
| April 1, 2025 | Arsenic | Monitoring | Resolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Arsenic | Inorganic | 1 | No |
| Stage 1 DBP Rule | Treatment Failure | 1 | No |
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 1 (High Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
Coverage: Service area ZIP codes sourced from EPA Community Water System Service Area Boundaries v3 (March 2026 release). These ZIPs reflect the actual deployment footprint recorded by MT or modeled from parcel and building-footprint data.
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for Big Sky County Water and Sewer District 363 (MT0002385) on EPA.gov.
Frequently Asked Questions
Is Big Sky County Water and Sewer District 363 water safe to drink?
Big Sky County Water and Sewer District 363 has only monitoring/reporting violations, which are procedural in nature. The system meets federal health-based standards.
How many people does Big Sky County Water and Sewer District 363 serve?
Big Sky County Water and Sewer District 363 serves approximately 4,132 people across 2 ZIP codes in Montana.
Where does Big Sky County Water and Sewer District 363 get its water?
The primary water source is groundwater.
Water Source & Treatment
Where this water originates and how it's treated before reaching your tap.
Source: BIG SKY COUNTY WATER AND SEWER DIST 363 Consumer Confidence Report.
ZipCheckup is not affiliated with this water utility. Treatment and source data are sourced from the utility's published CCR filings.
The source water assessment report for your water system provides additional information on your source water's susceptibility to contamination. To access this report please go to: https://deq.mt.gov/water/Programs/dw-sourcewater
Treatment regime
How this utility classifies its treatment process and what each reported treatment chemical does.
Watershed exposure sources reported
Land-use and natural conditions identified in the utility's source-water assessment as potential contamination sources upstream of treatment.
Treatment classification and chemical list sourced from BIG SKY COUNTY WATER AND SEWER DIST 363 Consumer Confidence Report.
Treatment intensity is a ZipCheckup-derived classification based on the chemicals and processes the utility reports. Chemicals and contamination sources are taken verbatim from the utility's CCR filing. Routine federal monitoring and contaminant testing shown elsewhere on this page determine whether the water meets safety standards, not the treatment classification.
Federal UCMR5 PFAS Monitoring: Detected
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). PFAS compounds were detected below the current state-enforceable MCL.
Current MCL reflects the lowest state-enforceable limit (NYS 10 ppt for PFOA/PFOS, effective August 2020). The federal final MCL of 4 ppt for PFOA/PFOS (EPA April 2024 rule) is not enforceable until April 2029. Detections above 4 ppt but below 10 ppt are below current MCL but above the future federal limit.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
Lead Service Line Inventory
Service line breakdown reported under the federal Lead and Copper Rule Improvements (LCRI) inventory requirement:
This system reports zero confirmed lead service lines in its inventory. Unknown-material counts may still warrant verification.
Federal LCRI rule (effective October 2024) requires every public water system to inventory its service lines and complete lead-line replacement within 10 years.
Source: EPA SDWIS Federal Service Line Inventory (Phase 2) · Submitted 2026
ZipCheckup is not affiliated with the utility or state agency. Inventory figures render verbatim from the public LCRI submission cited above; ZipCheckup does not perform inspections or replacements.
Frequently Asked Questions
What You Can Do
Test your water
Home test kits can detect lead, bacteria, and other contaminants at your tap. Find the right filter →
Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
Big Sky County Water and Sewer District 363 (EPA ID: MT0002385) — request the latest Consumer Confidence Report or ask about specific contaminants.