City of Mountain House
EPA ID: CA3910027 · 24,948 people served · 2 ZIP codes
ZipCheckup's reading of EPA SDWIS for City of Mountain House (CA3910027): no EPA violations recorded in the last five years. Federal monitoring records confirm City of Mountain House has operated without any EPA violations for the full five-year window - covering every contaminant category and reporting cycle across a service area of approximately 24,948 residents, with no gaps in the compliance record.
Data: EPA SDWIS
Service Area Map
Coverage area for City of Mountain House Source: EPA SDWIS service area boundaries.
Service area boundary - Grade A
Service Area Demographics
The City of Mountain House serves a community with a median household income of $142,935 and an estimated 40,011 residents across its service area.
Environmental Justice Note: 55% of the population in this service area is classified as disadvantaged under EPA's EJScreen criteria. Communities with higher disadvantaged populations often face disproportionate environmental and health burdens, including aging water infrastructure and limited resources for remediation.
🌊 Where Does Your Water Come From?
City of Mountain House's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
Superfund Proximity Note: This service area ranks in the 70th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
Comparable Water Systems
Similar-sized systems in California
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
City of Mountain House (EPA ID: CA3910027) is a community water system in California that serves approximately 24,948 people from surface water sources.
This system provides water to 2 ZIP codes across 1 community.
ZIP-Area Home Safety Context: A (100/100)
This is the average Home Safety Score for 1 of 2 service-area ZIP codes with all required score domains observed. It is not a grade for the water utility.
Model 4.0.0 uses SDWIS identity plus accepted ECHO SDWA lifecycle-based water compliance, the UCMR 5 PFAS MCL screen, EPA radon zone, and annual EPA AirData AQI across three equally weighted domains. Missing required evidence suppresses the score.
Violation History
Lead & Copper
EPA Lead and Copper Rule evidence attributed directly to this water system:
| Lead Level | Exceeds Action Level | Sample Date |
|---|---|---|
| 0 mg/L | No | N/A |
No copper action-level exceedance record appears for this PWSID in the accepted LCR snapshot. This does not establish a clean copper measurement.
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 3 (Low Risk)
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 CA 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 City of Mountain House (CA3910027) on EPA.gov.
Frequently Asked Questions
Is City of Mountain House water safe to drink?
The accepted 2026Q2 ECHO snapshot contains zero violation records for City of Mountain House in the inclusive 2021-2026 record-year window. This is a compliance-record finding, not a guarantee about water at a specific tap.
How many people does City of Mountain House serve?
City of Mountain House serves approximately 24,948 people across 2 ZIP codes in California.
Where does City of Mountain House get its water?
The primary water source is surface water.
Federal UCMR5 PFAS Monitoring: Tested Clean
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). No PFAS compounds were detected.
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 →
Frequently Asked Questions
How to cite this page
ZipCheckup. (n.d.). City of Mountain House, CA: Serves 25K People. https://zipcheckup.com/water-system/ca3910027/
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title = {{City of Mountain House, CA: Serves 25K People}},
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url = {https://zipcheckup.com/water-system/ca3910027/}
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