Gswc - Claremont
EPA ID: CA1910024 · 39,730 people served · 4 ZIP codes
ZipCheckup's reading of EPA records for Gswc - Claremont (CA1910024): a UCMR5 PFAS sample above the level of an EPA PFAS MCL, which takes effect in 2029; this is not a violation. No violations appear in the federal EPA file for Gswc - Claremont, which supplies 39,730 people.
Data: EPA SDWIS
Service Area Map
Coverage area for Gswc - Claremont Source: EPA SDWIS service area boundaries.
Service area boundary
Demographics of ZIP Codes Served
The ZIP codes associated with Gswc - Claremont have a median household income of $111,789 and about 121,403 residents live in those ZIP codes (Census; not the number of people this system supplies). Approximately 79% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
Environmental Justice Note: On average, 50% 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?
Gswc - Claremont'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 68th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
PFAS in ZIP Codes This System Serves
PFAS ("forever chemicals") have been reported in samples from water systems associated with the ZIP codes in this system's area. These results can come from other water systems serving the same ZIP codes; check the UCMR5 section for any results reported for this system. 8 detections recorded. 3 detections are above the level of a federal PFAS MCL (4 ppt for PFOA and PFOS), with compliance required from 2029.
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
Gswc - Claremont (EPA ID: CA1910024) is a community water system in California that serves approximately 39,730 people from surface water sources.
This system provides water to 4 ZIP codes across 4 communities.
Violation History
Lead & Copper
EPA Lead and Copper Rule evidence attributed directly to this water system:
| Lead Level | Exceeds Action Level | Sample Date |
|---|---|---|
| 0.0056 mg/L | No | 2026-12-31 |
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
4 of 4 ZIP records with known zones are in EPA Radon Zone 2.
The EPA recommends testing all homes regardless of radon zone. County radon zones cannot replace an in-home radon test.
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 Gswc - Claremont (CA1910024) on EPA.gov.
Frequently Asked Questions
Is Gswc - Claremont water safe to drink?
The accepted 2026Q2 ECHO snapshot contains zero violation records for Gswc - Claremont 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 Gswc - Claremont serve?
Gswc - Claremont serves approximately 39,730 people across 4 ZIP codes in California.
Where does Gswc - Claremont get its water?
The primary water source is surface water.
Federal UCMR5 PFAS Monitoring: Sample Above an EPA MCL Value or State Standard
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). One or more PFAS measurements were above the level of the EPA MCL for that compound (April 2024 rule, which takes effect in 2029) or above an applicable state drinking-water standard; a monitoring result above that level is not by itself a violation.
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.). Gswc - Claremont, CA: Serves 40K People. https://zipcheckup.com/water-system/ca1910024/
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title = {{Gswc - Claremont, CA: Serves 40K People}},
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url = {https://zipcheckup.com/water-system/ca1910024/}
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