City of Mountain House
EPA ID: CA3910027 · 24,948 people served · 2 ZIP codes
ZipCheckup's reading of EPA records for City of Mountain House (CA3910027): no drinking-water violations recorded since 2021. City of Mountain House is listed without violations in federal records, across a service area of 24,948 people.
Data: EPA SDWIS
Service Area Map
Coverage area for City of Mountain House Source: EPA SDWIS service area boundaries.
Service area boundary - average Home Safety grade of mapped ZIPs: A
Demographics of ZIP Codes Served
The ZIP codes associated with City of Mountain House have a median household income of $142,935 and about 40,011 residents live in those ZIP codes (Census; not the number of people this system supplies).
Environmental Justice Note: On average, 55% of census tracts in the counties mapped to this service area are designated disadvantaged by the federal Climate and Economic Justice Screening Tool (CEJST, 2022 version). 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
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: Ask your water utility whether running cold water for 2 minutes is enough to flush your plumbing before drinking.
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 available EPA compliance records 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: No PFAS Reported Above Reporting Levels
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). No PFAS compounds were reported above UCMR5 minimum reporting levels.
EPA's April 2024 PFAS rule sets MCLs of 4 ppt for PFOA and PFOS and 10 ppt for PFHxS, PFNA and HFPO-DA (GenX); water systems must comply from 2029. Other PFAS compounds have no individual federal MCL. A state standard is shown only where this system's state has its own enforceable PFAS limit. Detection results are EPA UCMR5 samples, not a measurement at your tap.
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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