City of Cornelius
EPA ID: OR4100218 · 14,490 people served · 4 ZIP codes
The EPA enforcement database lists 6 active violations for City of Cornelius — a provider that delivers drinking water to approximately 14,490 people and has not yet formally resolved those findings.
Data: EPA SDWIS Last verified: 2026-04-02
Compliance Trajectory
Worsening · Risk tier: High · 95% chance of violation in next 12 months
Violations went from 2 (2021) to 2 (2025). The pattern suggests growing compliance challenges.
Service Area Map
Coverage area for City of Cornelius Source: EPA SDWIS service area boundaries.
Service area boundary — Grade B
Service Area Demographics
The City of Cornelius serves a community with a median household income of $99,565 and an estimated 148,192 residents across its service area. Approximately 46% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
🌊 Where Does Your Water Come From?
City of Cornelius'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.
About 2% of homes in Washington County, Oregon rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Infrastructure Risk
Detected Contaminants
How City of Cornelius compares to EPA limits
What This Means For You
Contaminant 0700 at 20 mg/L exceeds the EPA maximum of mg/L.
Dichloroacetic Acid at 1 mg/L exceeds the EPA maximum of 0.06 mg/L.
Total Trihalomethanes (TTHM) at 1 mg/L exceeds the EPA maximum of 0.08 mg/L. Bladder & rectal cancer risk; reproductive concerns. Consider granular activated carbon (GAC) filtration.
Surface Water Treatment Rule at 9 mg/L exceeds the EPA maximum of mg/L.
Lead and Copper Rule at 2 mg/L exceeds the EPA maximum of mg/L.
Total Trihalomethanes (TTHM) was detected in this water system. granular activated carbon (GAC) filtration can reduce exposure.
Find a certified water filter →Comparable Water Systems
Similar-sized systems in Oregon
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 Cornelius, (EPA ID: OR4100218) is a community water system in Oregon that serves approximately 14,490 people from surface water sources.
This system provides water to 4 ZIP codes across 3 communities.
Average Home Safety Score: B (76/100)
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 |
|---|---|---|---|
| July 1, 2025 | Surface Water Treatment Rule | Monitoring | Unresolved |
| April 10, 2025 | Lead and Copper Rule | Monitoring | Unresolved |
| March 1, 2025 | Contaminant 0700 | Monitoring | Resolved |
| January 1, 2025 | Contaminant 0700 | Monitoring | Resolved |
| October 17, 2024 | Stage 2 DBP Rule | Health-based | Unresolved |
| October 1, 2024 | Surface Water Treatment Rule | Monitoring | Unresolved |
| July 1, 2024 | Surface Water Treatment Rule | Monitoring | Resolved |
| January 1, 2024 | Contaminant 3028 | Monitoring | Unresolved |
| October 1, 2023 | Surface Water Treatment Rule | Monitoring | Resolved |
| October 1, 2023 | Stage 1 DBP Rule | Monitoring | Resolved |
| August 1, 2023 | Contaminant 0700 | Monitoring | Resolved |
| July 1, 2023 | Surface Water Treatment Rule | Monitoring | Resolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Contaminant 0700 | Other Violation | 20 | Yes |
| Surface Water Treatment Rule | Treatment Failure | 9 | No |
| Lead and Copper Rule | Treatment Failure | 2 | No |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 1 | No |
| Dichloroacetic Acid | Disinfection Byproducts | 1 | No |
| Contaminant 3028 | Other Violation | 1 | No |
| Stage 1 DBP Rule | Treatment Failure | 1 | No |
| Stage 2 DBP Rule | Treatment Failure | 1 | Yes |
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
| ZIP Code | Lead Level | Exceeds Limit | Sample Date |
|---|---|---|---|
| 97113 | 0.001 mg/L | No | N/A |
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 2 (Moderate 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 OR 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 Cornelius (OR4100218) on EPA.gov.
Frequently Asked Questions
Is City of Cornelius water safe to drink?
City of Cornelius has recorded 4 health-based violations in the past 5 years. While the system is required to treat water to meet federal standards, you may want to consider additional precautions such as a certified water filter.
How many people does City of Cornelius serve?
City of Cornelius serves approximately 14,490 people across 4 ZIP codes in Oregon.
Where does City of Cornelius 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 →
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.
How Water Systems Appear in Rankings
Water systems are evaluated by violation history, contaminant detections, and service population. Larger systems with more service connections appear in more rankings.
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
City of Cornelius (EPA ID: OR4100218) — request the latest Consumer Confidence Report or ask about specific contaminants.